Struts2源代码分析

shenhua

贡献于2011-07-22

字数:61870 关键词: Struts2 Web框架

1. Struts2架构图 请求首先通过Filter chain,Filter主要包括ActionContextCleanUp,它主要清理当前线程的ActionContext和Dispatcher;FilterDispatcher主要通过AcionMapper来决定需要调用哪个Action。 ActionMapper取得了ActionMapping后,在Dispatcher的serviceAction方法里创建ActionProxy,ActionProxy创建ActionInvocation,然后ActionInvocation调用Interceptors,执行Action本身,创建Result并返回,当然,如果要在返回之前做些什么,可以实现PreResultListener。 2. Struts2部分类介绍 这部分从Struts2参考文档中翻译就可以了。 ActionMapper ActionMapper其实是HttpServletRequest和Action调用请求的一个映射,它屏蔽了Action对于Request等java Servlet类的依赖。Struts2中它的默认实现类是DefaultActionMapper,ActionMapper很大的用处可以根据自己的需要来设计url格式,它自己也有Restful的实现,具体可以参考文档的docs\actionmapper.html。 ActionProxy&ActionInvocation Action的一个代理,由ActionProxyFactory创建,它本身不包括Action实例,默认实现DefaultActionProxy是由ActionInvocation持有Action实例。ActionProxy作用是如何取得Action,无论是本地还是远程。而ActionInvocation的作用是如何执行Action,拦截器的功能就是在ActionInvocation中实现的。 ConfigurationProvider&Configuration ConfigurationProvider就是Struts2中配置文件的解析器,Struts2中的配置文件主要是尤其实现类XmlConfigurationProvider及其子类StrutsXmlConfigurationProvider来解析。 3. Struts2请求流程 1、客户端发送请求 2、请求先通过ActionContextCleanUp-->FilterDispatcher 3、FilterDispatcher通过ActionMapper来决定这个Request需要调用哪个Action 4、如果ActionMapper决定调用某个Action,FilterDispatcher把请求的处理交给ActionProxy,这儿已经转到它的Delegate--Dispatcher来执行 5、ActionProxy根据ActionMapping和ConfigurationManager找到需要调用的Action类 6、ActionProxy创建一个ActionInvocation的实例 7、ActionInvocation调用真正的Action,当然这涉及到相关拦截器的调用 8、Action执行完毕,ActionInvocation创建Result并返回,当然,如果要在返回之前做些什么,可以实现PreResultListener。添加PreResultListener可以在Interceptor中实现。 首先强调一下struts2的线程程安全,在Struts2中大量采用ThreadLocal线程局部变量的方法来保证线程的安全,像Dispatcher等都是通过ThreadLocal来保存变量值,使得每个线程都有自己独立的实例变量,互不相干. 接下来就从Dispatcher开始看起,先看其构造函数: //创建Dispatcher,此类是一个Delegate,它是真正完成根据url解析转向,读取对应Action的地方 public Dispatcher(ServletContext servletContext, Map initParams) { this.servletContext = servletContext; //配置在web.xml中的param参数 this.initParams = initParams; } //创建Dispatcher,此类是一个Delegate,它是真正完成根据url解析转向,读取对应Action的地方 public Dispatcher(ServletContext servletContext, Map initParams) { this.servletContext = servletContext; //配置在web.xml中的param参数 this.initParams = initParams; } 我们再看在FilterDispatcher创建Dispatcher的: protected Dispatcher createDispatcher(FilterConfig filterConfig) { Map params = new HashMap(); for (Enumeration e = filterConfig.getInitParameterNames(); e.hasMoreElements();) { String name = (String) e.nextElement(); String value = filterConfig.getInitParameter(name); params.put(name, value); } 都可以从FilterConfig中得到 return new Dispatcher(filterConfig.getServletContext(), params); } protected Dispatcher createDispatcher(FilterConfig filterConfig) { Map params = new HashMap(); for (Enumeration e = filterConfig.getInitParameterNames(); e.hasMoreElements();) { String name = (String) e.nextElement(); String value = filterConfig.getInitParameter(name); params.put(name, value); } 都可以从FilterConfig中得到 return new Dispatcher(filterConfig.getServletContext(), params); } 分七步载入各种配置属性,都是通过ConfigurationProvider接口进行的,这个接口提供init(),destroy(),register()等方法. 将各种ConfigurationProvider初始化之后将实例添加到ConfigurationManager的List里面. 最后通过循环调用List里的这些destroy(),register()等方法实现对配置文件的属性进行注册和销毁等功能. 下面将分析这七层功夫是怎样一步步练成的. 首先是init_DefaultProperties() 创建Dispatcher之后,来看init()方法 init()方法是用来Load用户配置文件,资源文件以及默认的配置文件. 主要分七步走,看下面注释 public void init() { if (configurationManager == null) { //设置ConfigurationManager的defaultFrameworkBeanName. //这里DEFAULT_BEAN_NAME为struts,这是xwork框架的内容,Framework可以是xwork,struts,webwork等 configurationManager = new ConfigurationManager(BeanSelectionProvider.DEFAULT_BEAN_NAME); } //读取properties信息,默认的default.properties, init_DefaultProperties(); // [1] //读取xml配置文件 init_TraditionalXmlConfigurations(); // [2] //读取用户自定义的struts.properties init_LegacyStrutsProperties(); // [3] //自定义的configProviders init_CustomConfigurationProviders(); // [5] //载入FilterDispatcher传进来的initParams init_FilterInitParameters() ; // [6] //将配置文件中的bean与具体的类映射 init_AliasStandardObjects() ; // [7] //构建一个用于依赖注射的Container对象 //在这里面会循环调用上面七个ConfigurationProvider的register方法 //其中的重点就是DefaultConfiguration的#reload()方法 Container container = init_PreloadConfiguration(); container.inject(this); init_CheckConfigurationReloading(container); init_CheckWebLogicWorkaround(container); if (!dispatcherListeners.isEmpty()) { for (DispatcherListener l : dispatcherListeners) { l.dispatcherInitialized(this); } } } public void init() { if (configurationManager == null) { //设置ConfigurationManager的defaultFrameworkBeanName. //这里DEFAULT_BEAN_NAME为struts,这是xwork框架的内容,Framework可以是xwork,struts,webwork等 configurationManager = new ConfigurationManager(BeanSelectionProvider.DEFAULT_BEAN_NAME); } //读取properties信息,默认的default.properties, init_DefaultProperties(); // [1] //读取xml配置文件 init_TraditionalXmlConfigurations(); // [2] //读取用户自定义的struts.properties init_LegacyStrutsProperties(); // [3] //自定义的configProviders init_CustomConfigurationProviders(); // [5] //载入FilterDispatcher传进来的initParams init_FilterInitParameters() ; // [6] //将配置文件中的bean与具体的类映射 init_AliasStandardObjects() ; // [7] //构建一个用于依赖注射的Container对象 //在这里面会循环调用上面七个ConfigurationProvider的register方法 //其中的重点就是DefaultConfiguration的#reload()方法 Container container = init_PreloadConfiguration(); container.inject(this); init_CheckConfigurationReloading(container); init_CheckWebLogicWorkaround(container); if (!dispatcherListeners.isEmpty()) { for (DispatcherListener l : dispatcherListeners) { l.dispatcherInitialized(this); } } } 分七步载入各种配置属性,都是通过ConfigurationProvider接口进行的,这个接口提供init(),destroy(),register()等方法. 将各种ConfigurationProvider初始化之后将实例添加到ConfigurationManager的List里 面. 最后通过循环调用List里的这些destroy(),register()等方法实现对配置文件的属性进行注册和销毁等功能. 下面将分析这七层功夫是怎样一步步练成的. 首先是init_DefaultProperties() private void init_DefaultProperties() { configurationManager.addConfigurationProvider(new DefaultPropertiesProvider()); } 接来看DefaultPropertiesProvider好了,DefaultPropertiesProvider实际上只是实现了register()方法 public void register(ContainerBuilder builder, LocatableProperties props) throws ConfigurationException { Settings defaultSettings = null; try { defaultSettings = new PropertiesSettings("org/apache/struts2/default"); } catch (Exception e) { throw new ConfigurationException("Could not find or error in org/apache/struts2/default.properties", e); } loadSettings(props, defaultSettings); } private void init_DefaultProperties() { configurationManager.addConfigurationProvider(new DefaultPropertiesProvider()); } 接来看DefaultPropertiesProvider好了,DefaultPropertiesProvider实际上只是实现了register()方法 public void register(ContainerBuilder builder, LocatableProperties props) throws ConfigurationException { Settings defaultSettings = null; try { defaultSettings = new PropertiesSettings("org/apache/struts2/default"); } catch (Exception e) { throw new ConfigurationException("Could not find or error in org/apache/struts2/default.properties", e); } loadSettings(props, defaultSettings); } //PropertiesSettings构造方法 //读取org/apache/struts2/default.properties的配置信息,如果项目中需要覆盖,可以在classpath里的struts.properties里覆写 public PropertiesSettings(String name) { URL settingsUrl = ClassLoaderUtils.getResource(name + ".properties", getClass()); if (settingsUrl == null) { LOG.debug(name + ".properties missing"); settings = new LocatableProperties(); return; } settings = new LocatableProperties(new LocationImpl(null, settingsUrl.toString())); // Load settings InputStream in = null; try { in = settingsUrl.openStream(); settings.load(in); } catch (IOException e) { throw new StrutsException("Could not load " + name + ".properties:" + e, e); } finally { if(in != null) { try { in.close(); } catch(IOException io) { LOG.warn("Unable to close input stream", io); } } } } //loadSettings主要是将progerty的value和Locale从上面PropertiesSettings中取得并存放到LocatableProperties props //这个props是register的一个入参. protected void loadSettings(LocatableProperties props, final Settings settings) { // We are calling the impl methods to get around the single instance of Settings that is expected for (Iterator i = settings.listImpl(); i.hasNext(); ) { String name = (String) i.next(); props.setProperty(name, settings.getImpl(name), settings.getLocationImpl(name)); } } //PropertiesSettings构造方法 //读取org/apache/struts2/default.properties的配置信息,如果项目中需要覆盖,可以在classpath里的struts.properties里覆写 public PropertiesSettings(String name) { URL settingsUrl = ClassLoaderUtils.getResource(name + ".properties", getClass()); if (settingsUrl == null) { LOG.debug(name + ".properties missing"); settings = new LocatableProperties(); return; } settings = new LocatableProperties(new LocationImpl(null, settingsUrl.toString())); // Load settings InputStream in = null; try { in = settingsUrl.openStream(); settings.load(in); } catch (IOException e) { throw new StrutsException("Could not load " + name + ".properties:" + e, e); } finally { if(in != null) { try { in.close(); } catch(IOException io) { LOG.warn("Unable to close input stream", io); } } } } //loadSettings主要是将progerty的value和Locale从上面PropertiesSettings中取得并存放到LocatableProperties props //这个props是register的一个入参. protected void loadSettings(LocatableProperties props, final Settings settings) { // We are calling the impl methods to get around the single instance of Settings that is expected for (Iterator i = settings.listImpl(); i.hasNext(); ) { String name = (String) i.next(); props.setProperty(name, settings.getImpl(name), settings.getLocationImpl(name)); } } 再来看第二步:init_TraditionalXmlConfigurations() private void init_TraditionalXmlConfigurations() { //首先读取web.xml中的config初始参数值 //如果没有配置就使用默认的DEFAULT_CONFIGURATION_PATHS:"struts-default.xml,struts-plugin.xml,struts.xml", //这儿就可以看出为什么默认的配置文件必须取名为这三个名称了 //如果不想使用默认的名称,直接在web.xml中配置config初始参数即可 String configPaths = initParams.get("config"); if (configPaths == null) { configPaths = DEFAULT_CONFIGURATION_PATHS; } String[] files = configPaths.split("\\s*[,]\\s*"); for (String file : files) { if (file.endsWith(".xml")) { if ("xwork.xml".equals(file)) { //XmlConfigurationProvider负责解析xwork.xml configurationManager.addConfigurationProvider(new XmlConfigurationProvider(file, false)); } else { //其它xml都是由StrutsXmlConfigurationProvider来解析 configurationManager.addConfigurationProvider(new StrutsXmlConfigurationProvider(file, false, servletContext)); } } else { throw new IllegalArgumentException("Invalid configuration file name"); } } } private void init_TraditionalXmlConfigurations() { //首先读取web.xml中的config初始参数值 //如果没有配置就使用默认的DEFAULT_CONFIGURATION_PATHS:"struts-default.xml,struts-plugin.xml,struts.xml", //这儿就可以看出为什么默认的配置文件必须取名为这三个名称了 //如果不想使用默认的名称,直接在web.xml中配置config初始参数即可 String configPaths = initParams.get("config"); if (configPaths == null) { configPaths = DEFAULT_CONFIGURATION_PATHS; } String[] files = configPaths.split("\\s*[,]\\s*"); for (String file : files) { if (file.endsWith(".xml")) { if ("xwork.xml".equals(file)) { //XmlConfigurationProvider负责解析xwork.xml configurationManager.addConfigurationProvider(new XmlConfigurationProvider(file, false)); } else { //其它xml都是由StrutsXmlConfigurationProvider来解析 configurationManager.addConfigurationProvider(new StrutsXmlConfigurationProvider(file, false, servletContext)); } } else { throw new IllegalArgumentException("Invalid configuration file name"); } } } 对于其它配置文件只用StrutsXmlConfigurationProvider,此类继承XmlConfigurationProvider,而XmlConfigurationProvider又实现ConfigurationProvider接口。 类XmlConfigurationProvider负责配置文件的读取和解析, 首先通过init()中的loadDocuments(configFileName);利用DomHelper中的 public static Document parse(InputSource inputSource, Map dtdMappings) 将configFileName配置文件通过SAX解析方式按照DtdMappings解析成Document对象. 然后通过Provider的register()方法加载"bean"和"constant"属性,再通过loadPackages()加载package及package中的属性 addAction()方法负责读取标签,并将数据保存在ActionConfig中; addResultTypes()方法负责将标签转化为ResultTypeConfig对象; loadInterceptors()方法负责将标签转化为InterceptorConfi对象; loadInterceptorStack()方法负责将标签转化为InterceptorStackConfig对象; loadInterceptorStacks()方法负责将标签转化成InterceptorStackConfig对象。 而上面的方法最终会被addPackage()方法调用,addPackage又会被Provider的loadPackages()调用,将所读取到的数据汇集到PackageConfig对象中。 protected PackageConfig addPackage(Element packageElement) throws ConfigurationException { PackageConfig.Builder newPackage = buildPackageContext(packageElement); if (newPackage.isNeedsRefresh()) { return newPackage.build(); } // add result types (and default result) to this package addResultTypes(newPackage, packageElement); // load the interceptors and interceptor stacks for this package loadInterceptors(newPackage, packageElement); // load the default interceptor reference for this package loadDefaultInterceptorRef(newPackage, packageElement); // load the default class ref for this package loadDefaultClassRef(newPackage, packageElement); // load the global result list for this package loadGlobalResults(newPackage, packageElement); // load the global exception handler list for this package loadGobalExceptionMappings(newPackage, packageElement); // get actions NodeList actionList = packageElement.getElementsByTagName("action"); for (int i = 0; i < actionList.getLength(); i++) { Element actionElement = (Element) actionList.item(i); addAction(actionElement, newPackage); } // load the default action reference for this package loadDefaultActionRef(newPackage, packageElement); PackageConfig cfg = newPackage.build(); configuration.addPackageConfig(cfg.getName(), cfg); return cfg; } loadConfigurationFiles解析读取xml中的内容 private List loadConfigurationFiles(String fileName, Element includeElement) { ... //通过DomHelper调用SAX进行解析xml doc = DomHelper.parse(in, dtdMappings); ... Element rootElement = doc.getDocumentElement(); NodeList children = rootElement.getChildNodes(); int childSize = children.getLength(); for (int i = 0; i < childSize; i++) { Node childNode = children.item(i); if (childNode instanceof Element) { Element child = (Element) childNode; final String nodeName = child.getNodeName(); if ("include".equals(nodeName)) { String includeFileName = child.getAttribute("file"); //解析每个action配置是,对于include文件可以使用通配符*来进行配置 //如Struts.xml中可配置成 if (includeFileName.indexOf('*') != -1) { ClassPathFinder wildcardFinder = new ClassPathFinder(); wildcardFinder.setPattern(includeFileName); Vector wildcardMatches = wildcardFinder.findMatches(); for (String match : wildcardMatches) { //递归Load子file中的 docs.addAll(loadConfigurationFiles(match, child)); } } else { docs.addAll(loadConfigurationFiles(includeFileName, child)); } } } } docs.add(doc); loadedFileUrls.add(url.toString()); ... return docs; } 首先强调一下struts2的线程程安全,在Struts2中大量采用ThreadLocal线程局部变量的方法来保证线程的安全,像Dispatcher等都是通过ThreadLocal来保存变量值,使得每个线程都有自己独立的实例变量,互不相干. 接下来就从Dispatcher开始看起,先看其构造函数: //创建Dispatcher,此类是一个Delegate,它是真正完成根据url解析转向,读取对应Action的地方 public Dispatcher(ServletContext servletContext, Map initParams) { this.servletContext = servletContext; //配置在web.xml中的param参数 this.initParams = initParams; } //创建Dispatcher,此类是一个Delegate,它是真正完成根据url解析转向,读取对应Action的地方 public Dispatcher(ServletContext servletContext, Map initParams) { this.servletContext = servletContext; //配置在web.xml中的param参数 this.initParams = initParams; } 我们再看在FilterDispatcher创建Dispatcher的: protected Dispatcher createDispatcher(FilterConfig filterConfig) { Map params = new HashMap(); for (Enumeration e = filterConfig.getInitParameterNames(); e.hasMoreElements();) { String name = (String) e.nextElement(); String value = filterConfig.getInitParameter(name); params.put(name, value); } 都可以从FilterConfig中得到 return new Dispatcher(filterConfig.getServletContext(), params); } protected Dispatcher createDispatcher(FilterConfig filterConfig) { Map params = new HashMap(); for (Enumeration e = filterConfig.getInitParameterNames(); e.hasMoreElements();) { String name = (String) e.nextElement(); String value = filterConfig.getInitParameter(name); params.put(name, value); } 都可以从FilterConfig中得到 return new Dispatcher(filterConfig.getServletContext(), params); } 分七步载入各种配置属性,都是通过ConfigurationProvider接口进行的,这个接口提供init(),destroy(),register()等方法. 将各种ConfigurationProvider初始化之后将实例添加到ConfigurationManager的List里面. 最后通过循环调用List里的这些destroy(),register()等方法实现对配置文件的属性进行注册和销毁等功能. 下面将分析这七层功夫是怎样一步步练成的. 首先是init_DefaultProperties() 创建Dispatcher之后,来看init()方法 init()方法是用来Load用户配置文件,资源文件以及默认的配置文件. 主要分七步走,看下面注释 public void init() { if (configurationManager == null) { //设置ConfigurationManager的defaultFrameworkBeanName. //这里DEFAULT_BEAN_NAME为struts,这是xwork框架的内容,Framework可以是xwork,struts,webwork等 configurationManager = new ConfigurationManager(BeanSelectionProvider.DEFAULT_BEAN_NAME); } //读取properties信息,默认的default.properties, init_DefaultProperties(); // [1] //读取xml配置文件 init_TraditionalXmlConfigurations(); // [2] //读取用户自定义的struts.properties init_LegacyStrutsProperties(); // [3] //自定义的configProviders init_CustomConfigurationProviders(); // [5] //载入FilterDispatcher传进来的initParams init_FilterInitParameters() ; // [6] //将配置文件中的bean与具体的类映射 init_AliasStandardObjects() ; // [7] //构建一个用于依赖注射的Container对象 //在这里面会循环调用上面七个ConfigurationProvider的register方法 //其中的重点就是DefaultConfiguration的#reload()方法 Container container = init_PreloadConfiguration(); container.inject(this); init_CheckConfigurationReloading(container); init_CheckWebLogicWorkaround(container); if (!dispatcherListeners.isEmpty()) { for (DispatcherListener l : dispatcherListeners) { l.dispatcherInitialized(this); } } } public void init() { if (configurationManager == null) { //设置ConfigurationManager的defaultFrameworkBeanName. //这里DEFAULT_BEAN_NAME为struts,这是xwork框架的内容,Framework可以是xwork,struts,webwork等 configurationManager = new ConfigurationManager(BeanSelectionProvider.DEFAULT_BEAN_NAME); } //读取properties信息,默认的default.properties, init_DefaultProperties(); // [1] //读取xml配置文件 init_TraditionalXmlConfigurations(); // [2] //读取用户自定义的struts.properties init_LegacyStrutsProperties(); // [3] //自定义的configProviders init_CustomConfigurationProviders(); // [5] //载入FilterDispatcher传进来的initParams init_FilterInitParameters() ; // [6] //将配置文件中的bean与具体的类映射 init_AliasStandardObjects() ; // [7] //构建一个用于依赖注射的Container对象 //在这里面会循环调用上面七个ConfigurationProvider的register方法 //其中的重点就是DefaultConfiguration的#reload()方法 Container container = init_PreloadConfiguration(); container.inject(this); init_CheckConfigurationReloading(container); init_CheckWebLogicWorkaround(container); if (!dispatcherListeners.isEmpty()) { for (DispatcherListener l : dispatcherListeners) { l.dispatcherInitialized(this); } } } 分七步载入各种配置属性,都是通过ConfigurationProvider接口进行的,这个接口提供init(),destroy(),register()等方法. 将各种ConfigurationProvider初始化之后将实例添加到ConfigurationManager的List里面. 最后通过循环调用List里的这些destroy(),register()等方法实现对配置文件的属性进行注册和销毁等功能. 下面将分析这七层功夫是怎样一步步练成的. 首先是init_DefaultProperties() private void init_DefaultProperties() { configurationManager.addConfigurationProvider(new DefaultPropertiesProvider()); } 接来看DefaultPropertiesProvider好了,DefaultPropertiesProvider实际上只是实现了register()方法 public void register(ContainerBuilder builder, LocatableProperties props) throws ConfigurationException { Settings defaultSettings = null; try { defaultSettings = new PropertiesSettings("org/apache/struts2/default"); } catch (Exception e) { throw new ConfigurationException("Could not find or error in org/apache/struts2/default.properties", e); } loadSettings(props, defaultSettings); } private void init_DefaultProperties() { configurationManager.addConfigurationProvider(new DefaultPropertiesProvider()); } 接来看DefaultPropertiesProvider好了,DefaultPropertiesProvider实际上只是实现了register()方法 public void register(ContainerBuilder builder, LocatableProperties props) throws ConfigurationException { Settings defaultSettings = null; try { defaultSettings = new PropertiesSettings("org/apache/struts2/default"); } catch (Exception e) { throw new ConfigurationException("Could not find or error in org/apache/struts2/default.properties", e); } loadSettings(props, defaultSettings); } //PropertiesSettings构造方法 //读取org/apache/struts2/default.properties的配置信息,如果项目中需要覆盖,可以在classpath里的struts.properties里覆写 public PropertiesSettings(String name) { URL settingsUrl = ClassLoaderUtils.getResource(name + ".properties", getClass()); if (settingsUrl == null) { LOG.debug(name + ".properties missing"); settings = new LocatableProperties(); return; } settings = new LocatableProperties(new LocationImpl(null, settingsUrl.toString())); // Load settings InputStream in = null; try { in = settingsUrl.openStream(); settings.load(in); } catch (IOException e) { throw new StrutsException("Could not load " + name + ".properties:" + e, e); } finally { if(in != null) { try { in.close(); } catch(IOException io) { LOG.warn("Unable to close input stream", io); } } } } //loadSettings主要是将progerty的value和Locale从上面PropertiesSettings中取得并存放到LocatableProperties props //这个props是register的一个入参. protected void loadSettings(LocatableProperties props, final Settings settings) { // We are calling the impl methods to get around the single instance of Settings that is expected for (Iterator i = settings.listImpl(); i.hasNext(); ) { String name = (String) i.next(); props.setProperty(name, settings.getImpl(name), settings.getLocationImpl(name)); } } //PropertiesSettings构造方法 //读取org/apache/struts2/default.properties的配置信息,如果项目中需要覆盖,可以在classpath里的struts.properties里覆写 public PropertiesSettings(String name) { URL settingsUrl = ClassLoaderUtils.getResource(name + ".properties", getClass()); if (settingsUrl == null) { LOG.debug(name + ".properties missing"); settings = new LocatableProperties(); return; } settings = new LocatableProperties(new LocationImpl(null, settingsUrl.toString())); // Load settings InputStream in = null; try { in = settingsUrl.openStream(); settings.load(in); } catch (IOException e) { throw new StrutsException("Could not load " + name + ".properties:" + e, e); } finally { if(in != null) { try { in.close(); } catch(IOException io) { LOG.warn("Unable to close input stream", io); } } } } //loadSettings主要是将progerty的value和Locale从上面PropertiesSettings中取得并存放到LocatableProperties props //这个props是register的一个入参. protected void loadSettings(LocatableProperties props, final Settings settings) { // We are calling the impl methods to get around the single instance of Settings that is expected for (Iterator i = settings.listImpl(); i.hasNext(); ) { String name = (String) i.next(); props.setProperty(name, settings.getImpl(name), settings.getLocationImpl(name)); } } 再来看第二步:init_TraditionalXmlConfigurations() private void init_TraditionalXmlConfigurations() { //首先读取web.xml中的config初始参数值 //如果没有配置就使用默认的DEFAULT_CONFIGURATION_PATHS:"struts-default.xml,struts-plugin.xml,struts.xml", //这儿就可以看出为什么默认的配置文件必须取名为这三个名称了 //如果不想使用默认的名称,直接在web.xml中配置config初始参数即可 String configPaths = initParams.get("config"); if (configPaths == null) { configPaths = DEFAULT_CONFIGURATION_PATHS; } String[] files = configPaths.split("\\s*[,]\\s*"); for (String file : files) { if (file.endsWith(".xml")) { if ("xwork.xml".equals(file)) { //XmlConfigurationProvider负责解析xwork.xml configurationManager.addConfigurationProvider(new XmlConfigurationProvider(file, false)); } else { //其它xml都是由StrutsXmlConfigurationProvider来解析 configurationManager.addConfigurationProvider(new StrutsXmlConfigurationProvider(file, false, servletContext)); } } else { throw new IllegalArgumentException("Invalid configuration file name"); } } } private void init_TraditionalXmlConfigurations() { //首先读取web.xml中的config初始参数值 //如果没有配置就使用默认的DEFAULT_CONFIGURATION_PATHS:"struts-default.xml,struts-plugin.xml,struts.xml", //这儿就可以看出为什么默认的配置文件必须取名为这三个名称了 //如果不想使用默认的名称,直接在web.xml中配置config初始参数即可 String configPaths = initParams.get("config"); if (configPaths == null) { configPaths = DEFAULT_CONFIGURATION_PATHS; } String[] files = configPaths.split("\\s*[,]\\s*"); for (String file : files) { if (file.endsWith(".xml")) { if ("xwork.xml".equals(file)) { //XmlConfigurationProvider负责解析xwork.xml configurationManager.addConfigurationProvider(new XmlConfigurationProvider(file, false)); } else { //其它xml都是由StrutsXmlConfigurationProvider来解析 configurationManager.addConfigurationProvider(new StrutsXmlConfigurationProvider(file, false, servletContext)); } } else { throw new IllegalArgumentException("Invalid configuration file name"); } } } 对于其它配置文件只用StrutsXmlConfigurationProvider,此类继承XmlConfigurationProvider,而XmlConfigurationProvider又实现ConfigurationProvider接口。 类XmlConfigurationProvider负责配置文件的读取和解析, 首先通过init()中的loadDocuments(configFileName);利用DomHelper中的 public static Document parse(InputSource inputSource, Map dtdMappings) 将configFileName配置文件通过SAX解析方式按照DtdMappings解析成Document对象. 然后通过Provider的register()方法加载"bean"和"constant"属性,再通过loadPackages()加载package及package中的属性 addAction()方法负责读取标签,并将数据保存在ActionConfig中; addResultTypes()方法负责将标签转化为ResultTypeConfig对象; loadInterceptors()方法负责将标签转化为InterceptorConfi对象; loadInterceptorStack()方法负责将标签转化为InterceptorStackConfig对象; loadInterceptorStacks()方法负责将标签转化成InterceptorStackConfig对象。 而上面的方法最终会被addPackage()方法调用,addPackage又会被Provider的loadPackages()调用,将所读取到的数据汇集到PackageConfig对象中。 protected PackageConfig addPackage(Element packageElement) throws ConfigurationException { PackageConfig.Builder newPackage = buildPackageContext(packageElement); if (newPackage.isNeedsRefresh()) { return newPackage.build(); } // add result types (and default result) to this package addResultTypes(newPackage, packageElement); // load the interceptors and interceptor stacks for this package loadInterceptors(newPackage, packageElement); // load the default interceptor reference for this package loadDefaultInterceptorRef(newPackage, packageElement); // load the default class ref for this package loadDefaultClassRef(newPackage, packageElement); // load the global result list for this package loadGlobalResults(newPackage, packageElement); // load the global exception handler list for this package loadGobalExceptionMappings(newPackage, packageElement); // get actions NodeList actionList = packageElement.getElementsByTagName("action"); for (int i = 0; i < actionList.getLength(); i++) { Element actionElement = (Element) actionList.item(i); addAction(actionElement, newPackage); } // load the default action reference for this package loadDefaultActionRef(newPackage, packageElement); PackageConfig cfg = newPackage.build(); configuration.addPackageConfig(cfg.getName(), cfg); return cfg; } loadConfigurationFiles解析读取xml中的内容 private List loadConfigurationFiles(String fileName, Element includeElement) { ... //通过DomHelper调用SAX进行解析xml doc = DomHelper.parse(in, dtdMappings); ... Element rootElement = doc.getDocumentElement(); NodeList children = rootElement.getChildNodes(); int childSize = children.getLength(); for (int i = 0; i < childSize; i++) { Node childNode = children.item(i); if (childNode instanceof Element) { Element child = (Element) childNode; final String nodeName = child.getNodeName(); if ("include".equals(nodeName)) { String includeFileName = child.getAttribute("file"); //解析每个action配置是,对于include文件可以使用通配符*来进行配置 //如Struts.xml中可配置成 if (includeFileName.indexOf('*') != -1) { ClassPathFinder wildcardFinder = new ClassPathFinder(); wildcardFinder.setPattern(includeFileName); Vector wildcardMatches = wildcardFinder.findMatches(); for (String match : wildcardMatches) { //递归Load子file中的 docs.addAll(loadConfigurationFiles(match, child)); } } else { docs.addAll(loadConfigurationFiles(includeFileName, child)); } } } } docs.add(doc); loadedFileUrls.add(url.toString()); ... return docs; } 接下来第三步:init_LegacyStrutsProperties() 调用的是调用的是LegacyPropertiesConfigurationProvider 通过比较前面DefaultPropertiesProvider与调用的是LegacyPropertiesConfigurationProvider. 发现DefaultPropertiesProvider继承自后者,但重写了register()方法,主要是生成PropertiesSetting的不同,前者是根据org/apache/struts2/default.properties 后者是根据struts.properties 我们展开register()中的Settings.getInstance(),最后是调用getDefaultInstance() private static Settings getDefaultInstance() { if (defaultImpl == null) { // Create bootstrap implementation //不带参数的DefaultSettings(),区别与DefaultPropertiesProvider中直接带default.properties参数 //不带参数就是默认为struts.propertes,并且加载struts.custom.properties所定义的properties文件 defaultImpl = new DefaultSettings(); // Create default implementation try { //STRUTS_CONFIGURATION为:struts.configuration //在struts.proterties中查找struts.configuration的值,这个值必须是org.apache.struts2.config.Configuration接口的实现类 //所以我有个困惑就是在下面的转换当中怎么将Configuration转换成Setting类型的... //这一点先放下了,有时间再研究 String className = get(StrutsConstants.STRUTS_CONFIGURATION); if (!className.equals(defaultImpl.getClass().getName())) { try { // singleton instances shouldn't be built accessing request or session-specific context data defaultImpl = (Settings) ObjectFactory.getObjectFactory().buildBean(Thread.currentThread().getContextClassLoader().loadClass(className), null); } catch (Exception e) { LOG.error("Settings: Could not instantiate the struts.configuration object, substituting the default implementation.", e); } } } catch (IllegalArgumentException ex) { // ignore } private static Settings getDefaultInstance() { if (defaultImpl == null) { // Create bootstrap implementation //不带参数的DefaultSettings(),区别与DefaultPropertiesProvider中直接带default.properties参数 //不带参数就是默认为struts.propertes,并且加载struts.custom.properties所定义的properties文件 defaultImpl = new DefaultSettings(); // Create default implementation try { //STRUTS_CONFIGURATION为:struts.configuration //在struts.proterties中查找struts.configuration的值,这个值必须是org.apache.struts2.config.Configuration接口的实现类 //所以我有个困惑就是在下面的转换当中怎么将Configuration转换成Setting类型的... //这一点先放下了,有时间再研究 String className = get(StrutsConstants.STRUTS_CONFIGURATION); if (!className.equals(defaultImpl.getClass().getName())) { try { // singleton instances shouldn't be built accessing request or session-specific context data defaultImpl = (Settings) ObjectFactory.getObjectFactory().buildBean(Thread.currentThread().getContextClassLoader().loadClass(className), null); } catch (Exception e) { LOG.error("Settings: Could not instantiate the struts.configuration object, substituting the default implementation.", e); } } } catch (IllegalArgumentException ex) { // ignore } 在2.1.6中去掉了第四步:init_ZeroConfiguration(); 第五步是自定义的configProviders private void init_CustomConfigurationProviders() { //从这里可以看到可以将自定义的Provider定义在web.xml中FilterDispatcher的param中:configProviders String configProvs = initParams.get("configProviders"); if (configProvs != null) { String[] classes = configProvs.split("\\s*[,]\\s*"); for (String cname : classes) { try { Class cls = ClassLoaderUtils.loadClass(cname, this.getClass()); ConfigurationProvider prov = (ConfigurationProvider)cls.newInstance(); configurationManager.addConfigurationProvider(prov); } ... } } } private void init_CustomConfigurationProviders() { //从这里可以看到可以将自定义的Provider定义在web.xml中FilterDispatcher的param中:configProviders String configProvs = initParams.get("configProviders"); if (configProvs != null) { String[] classes = configProvs.split("\\s*[,]\\s*"); for (String cname : classes) { try { Class cls = ClassLoaderUtils.loadClass(cname, this.getClass()); ConfigurationProvider prov = (ConfigurationProvider)cls.newInstance(); configurationManager.addConfigurationProvider(prov); } ... } } } 第六步:init_FilterInitParameters //从这里可以看出struts.properties中的属性不仅可以在struts.xml中以constant形式定义,而且可以在FilterDispatcher的param中定义 private void init_FilterInitParameters() { configurationManager.addConfigurationProvider(new ConfigurationProvider() { public void destroy() {} public void init(Configuration configuration) throws ConfigurationException {} public void loadPackages() throws ConfigurationException {} public boolean needsReload() { return false; } public void register(ContainerBuilder builder, LocatableProperties props) throws ConfigurationException { props.putAll(initParams);//在这里实现滴~ } }); } //从这里可以看出struts.properties中的属性不仅可以在struts.xml中以constant形式定义,而且可以在FilterDispatcher的param中定义 private void init_FilterInitParameters() { configurationManager.addConfigurationProvider(new ConfigurationProvider() { public void destroy() {} public void init(Configuration configuration) throws ConfigurationException {} public void loadPackages() throws ConfigurationException {} public boolean needsReload() { return false; } public void register(ContainerBuilder builder, LocatableProperties props) throws ConfigurationException { props.putAll(initParams);//在这里实现滴~ } }); } 第七步:init_AliasStandardObjects,使用BeanSelectionProvider 这是将配置文件中定义的与实际的类相映射,就是注入bean的依赖关系,这部分以后有时候再研究Container 接下来是看怎样调用这些ConfigurationProviders 展开init_PreloadConfiguration() private Container init_PreloadConfiguration() { Configuration config = configurationManager.getConfiguration(); Container container = config.getContainer(); boolean reloadi18n = Boolean.valueOf(container.getInstance(String.class, StrutsConstants.STRUTS_I18N_RELOAD)); LocalizedTextUtil.setReloadBundles(reloadi18n); return container; } //再看getConfiguration() public synchronized Configuration getConfiguration() { if (configuration == null) { setConfiguration(new DefaultConfiguration(defaultFrameworkBeanName)); try { //重点就是这个reloadContainer configuration.reloadContainer(getContainerProviders()); } catch (ConfigurationException e) { setConfiguration(null); throw new ConfigurationException("Unable to load configuration.", e); } } else { conditionalReload(); } return configuration; } private Container init_PreloadConfiguration() { Configuration config = configurationManager.getConfiguration(); Container container = config.getContainer(); boolean reloadi18n = Boolean.valueOf(container.getInstance(String.class, StrutsConstants.STRUTS_I18N_RELOAD)); LocalizedTextUtil.setReloadBundles(reloadi18n); return container; } //再看getConfiguration() public synchronized Configuration getConfiguration() { if (configuration == null) { setConfiguration(new DefaultConfiguration(defaultFrameworkBeanName)); try { //重点就是这个reloadContainer configuration.reloadContainer(getContainerProviders()); } catch (ConfigurationException e) { setConfiguration(null); throw new ConfigurationException("Unable to load configuration.", e); } } else { conditionalReload(); } return configuration; } 展开DefaultConfiguration中的reloadContainer public synchronized List reloadContainer(List providers) throws ConfigurationException { packageContexts.clear(); loadedFileNames.clear(); List packageProviders = new ArrayList(); //Struts2(xwork2)用Container来完成依赖注入的功能 //首先初始化一个ContainerBuilder,再由builder来保存接口与实现类或工厂类的对应关系 //然后通过builder.create(boolean)方法产生container //由container.getInstance(Class);就可以得到接口的实现实例了 //这一部分比较复杂,后面研究完成了,会单独拿出来讲,这里先弄清楚Xwork依赖注入的实现步骤就可以了 ContainerProperties props = new ContainerProperties(); ContainerBuilder builder = new ContainerBuilder(); for (final ContainerProvider containerProvider : providers) { //循环调用ConfigurationProvider的init和register方法,明白了吧,在这里统一循环调用 containerProvider.init(this); containerProvider.register(builder, props); } props.setConstants(builder); //注入依赖关系,在这里并不产生实例 builder.factory(Configuration.class, new Factory() { public Configuration create(Context context) throws Exception { return DefaultConfiguration.this; } }); ActionContext oldContext = ActionContext.getContext(); try { // Set the bootstrap container for the purposes of factory creation Container bootstrap = createBootstrapContainer(); setContext(bootstrap); //create已经注入依赖关系的Container container = builder.create(false); setContext(container); objectFactory = container.getInstance(ObjectFactory.class); // Process the configuration providers first for (final ContainerProvider containerProvider : providers) { if (containerProvider instanceof PackageProvider) { container.inject(containerProvider); //调用PackageProvider的loadPackages()方法,这里主要是针对XmlConfigurationProvider和StrutsXmlConfigurationProvider ((PackageProvider)containerProvider).loadPackages(); packageProviders.add((PackageProvider)containerProvider); } } // Then process any package providers from the plugins Set packageProviderNames = container.getInstanceNames(PackageProvider.class); if (packageProviderNames != null) { for (String name : packageProviderNames) { PackageProvider provider = container.getInstance(PackageProvider.class, name); provider.init(this); provider.loadPackages(); packageProviders.add(provider); } } rebuildRuntimeConfiguration(); } finally { if (oldContext == null) { ActionContext.setContext(null); } } return packageProviders; } Dispatcher已经在之前讲过,这就好办了。FilterDispatcher是Struts2的核心控制器,首先看一下init()方法。 public void init(FilterConfig filterConfig) throws ServletException { try { this.filterConfig = filterConfig; initLogging(); //创建dispatcher,前面都已经讲过啰 dispatcher = createDispatcher(filterConfig); dispatcher.init(); //注入将FilterDispatcher中的变量通过container注入,如下面的staticResourceLoader dispatcher.getContainer().inject(this); //StaticContentLoader在BeanSelectionProvider中已经被注入了依赖关系:DefaultStaticContentLoader //可以在struts-default.xml中的可以找到 staticResourceLoader.setHostConfig(new FilterHostConfig(filterConfig)); } finally { ActionContext.setContext(null); } } public void init(FilterConfig filterConfig) throws ServletException { try { this.filterConfig = filterConfig; initLogging(); //创建dispatcher,前面都已经讲过啰 dispatcher = createDispatcher(filterConfig); dispatcher.init(); //注入将FilterDispatcher中的变量通过container注入,如下面的staticResourceLoader dispatcher.getContainer().inject(this); //StaticContentLoader在BeanSelectionProvider中已经被注入了依赖关系:DefaultStaticContentLoader //可以在struts-default.xml中的可以找到 staticResourceLoader.setHostConfig(new FilterHostConfig(filterConfig)); } finally { ActionContext.setContext(null); } } //下面来看DefaultStaticContentLoader的setHostConfig public void setHostConfig(HostConfig filterConfig) { //读取初始参数pakages,调用parse(),解析成类似/org/apache/struts2/static,/template的数组 String param = filterConfig.getInitParameter("packages"); //"org.apache.struts2.static template org.apache.struts2.interceptor.debugging static" String packages = getAdditionalPackages(); if (param != null) { packages = param + " " + packages; } this.pathPrefixes = parse(packages); initLogging(filterConfig); } //下面来看DefaultStaticContentLoader的setHostConfig public void setHostConfig(HostConfig filterConfig) { //读取初始参数pakages,调用parse(),解析成类似/org/apache/struts2/static,/template的数组 String param = filterConfig.getInitParameter("packages"); //"org.apache.struts2.static template org.apache.struts2.interceptor.debugging static" String packages = getAdditionalPackages(); if (param != null) { packages = param + " " + packages; } this.pathPrefixes = parse(packages); initLogging(filterConfig); } 现在回去doFilter的方法,每当有一个Request,都会调用这些Filters的doFilter方法 public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) res; ServletContext servletContext = getServletContext(); String timerKey = "FilterDispatcher_doFilter: "; try { // FIXME: this should be refactored better to not duplicate work with the action invocation //先看看ValueStackFactory所注入的实现类OgnlValueStackFactory //new OgnlValueStack ValueStack stack = dispatcher.getContainer().getInstance(ValueStackFactory.class).createValueStack(); ActionContext ctx = new ActionContext(stack.getContext()); ActionContext.setContext(ctx); UtilTimerStack.push(timerKey); //如果是multipart/form-data就用MultiPartRequestWrapper进行包装 //MultiPartRequestWrapper是StrutsRequestWrapper的子类,两者都是HttpServletRequest实现 //此时在MultiPartRequestWrapper中就会把Files给解析出来,用于文件上传 //所有request都会StrutsRequestWrapper进行包装,StrutsRequestWrapper是可以访问ValueStack //下面是参见Dispatcher的wrapRequest // String content_type = request.getContentType(); //if(content_type!= null&&content_type.indexOf("multipart/form-data")!=-1){ //MultiPartRequest multi =getContainer().getInstance(MultiPartRequest.class); //request =new MultiPartRequestWrapper(multi,request,getSaveDir(servletContext)); //} else { // request = new StrutsRequestWrapper(request); // } request = prepareDispatcherAndWrapRequest(request, response); ActionMapping mapping; try { //根据url取得对应的Action的配置信息 //看一下注入的DefaultActionMapper的getMapping()方法.Action的配置信息存储在 ActionMapping对象中 mapping = actionMapper.getMapping(request, dispatcher.getConfigurationManager()); } catch (Exception ex) { log.error("error getting ActionMapping", ex); dispatcher.sendError(request, response, servletContext, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, ex); return; } //如果找不到对应的action配置,则直接返回。比如你输入***.jsp等等 //这儿有个例外,就是如果path是以“/struts”开头,则到初始参数packages配置的包路径去查找对应的静态资源并输出到页面流中,当然.class文件除外。如果再没有则跳转到404 if (mapping == null) { // there is no action in this request, should we look for a static resource? String resourcePath = RequestUtils.getServletPath(request); if ("".equals(resourcePath) && null != request.getPathInfo()) { resourcePath = request.getPathInfo(); } if (staticResourceLoader.canHandle(resourcePath)) { // 在DefaultStaticContentLoader中:return serveStatic && (resourcePath.startsWith("/struts") || resourcePath.startsWith("/static")); staticResourceLoader.findStaticResource(resourcePath, request, response); } else { // this is a normal request, let it pass through chain.doFilter(request, response); } // The framework did its job here return; } //正式开始Action的方法 dispatcher.serviceAction(request, response, servletContext, mapping); } finally { try { ActionContextCleanUp.cleanUp(req); } finally { UtilTimerStack.pop(timerKey); } } } public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) res; ServletContext servletContext = getServletContext(); String timerKey = "FilterDispatcher_doFilter: "; try { // FIXME: this should be refactored better to not duplicate work with the action invocation //先看看ValueStackFactory所注入的实现类OgnlValueStackFactory //new OgnlValueStack ValueStack stack = dispatcher.getContainer().getInstance(ValueStackFactory.class).createValueStack(); ActionContext ctx = new ActionContext(stack.getContext()); ActionContext.setContext(ctx); UtilTimerStack.push(timerKey); //如果是multipart/form-data就用MultiPartRequestWrapper进行包装 //MultiPartRequestWrapper是StrutsRequestWrapper的子类,两者都是HttpServletRequest实现 //此时在MultiPartRequestWrapper中就会把Files给解析出来,用于文件上传 //所有request都会StrutsRequestWrapper进行包装,StrutsRequestWrapper是可以访问ValueStack //下面是参见Dispatcher的wrapRequest // String content_type = request.getContentType(); //if(content_type!= null&&content_type.indexOf("multipart/form-data")!=-1){ //MultiPartRequest multi =getContainer().getInstance(MultiPartRequest.class); //request =new MultiPartRequestWrapper(multi,request,getSaveDir(servletContext)); //} else { // request = new StrutsRequestWrapper(request); // } request = prepareDispatcherAndWrapRequest(request, response); ActionMapping mapping; try { //根据url取得对应的Action的配置信息 //看一下注入的DefaultActionMapper的getMapping()方法.Action的配置信息存储在 ActionMapping对象中 mapping = actionMapper.getMapping(request, dispatcher.getConfigurationManager()); } catch (Exception ex) { log.error("error getting ActionMapping", ex); dispatcher.sendError(request, response, servletContext, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, ex); return; } //如果找不到对应的action配置,则直接返回。比如你输入***.jsp等等 //这儿有个例外,就是如果path是以“/struts”开头,则到初始参数packages配置的包路径去查找对应的静态资源并输出到页面流中,当然.class文件除外。如果再没有则跳转到404 if (mapping == null) { // there is no action in this request, should we look for a static resource? String resourcePath = RequestUtils.getServletPath(request); if ("".equals(resourcePath) && null != request.getPathInfo()) { resourcePath = request.getPathInfo(); } if (staticResourceLoader.canHandle(resourcePath)) { // 在DefaultStaticContentLoader中:return serveStatic && (resourcePath.startsWith("/struts") || resourcePath.startsWith("/static")); staticResourceLoader.findStaticResource(resourcePath, request, response); } else { // this is a normal request, let it pass through chain.doFilter(request, response); } // The framework did its job here return; } //正式开始Action的方法 dispatcher.serviceAction(request, response, servletContext, mapping); } finally { try { ActionContextCleanUp.cleanUp(req); } finally { UtilTimerStack.pop(timerKey); } } } //下面是ActionMapper接口的实现类 DefaultActionMapper的getMapping()方法的源代码: public ActionMapping getMapping(HttpServletRequest request, ConfigurationManager configManager) { ActionMapping mapping = new ActionMapping(); String uri = getUri(request);//得到请求路径的URI,如:testAtcion.action或testAction.do int indexOfSemicolon = uri.indexOf(";");//修正url的带;jsessionid 时找不到而且的bug uri = (indexOfSemicolon > -1) ? uri.substring(0, indexOfSemicolon) : uri; uri = dropExtension(uri, mapping);//删除扩展名,默认扩展名为action if (uri == null) { return null; } parseNameAndNamespace(uri, mapping, configManager);//匹配Action的name和namespace handleSpecialParameters(request, mapping);//去掉重复参数 //如果Action的name没有解析出来,直接返回     if (mapping.getName() == null) {       returnnull;     }     //下面处理形如testAction!method格式的请求路径     if (allowDynamicMethodCalls) {       // handle "name!method" convention.       String name = mapping.getName();       int exclamation = name.lastIndexOf("!");//!是Action名称和方法名的分隔符       if (exclamation != -1) {         mapping.setName(name.substring(0, exclamation));//提取左边为name         mapping.setMethod(name.substring(exclamation + 1));//提取右边的method       }     } return mapping; } //下面是ActionMapper接口的实现类 DefaultActionMapper的getMapping()方法的源代码: public ActionMapping getMapping(HttpServletRequest request, ConfigurationManager configManager) { ActionMapping mapping = new ActionMapping(); String uri = getUri(request);//得到请求路径的URI,如:testAtcion.action或testAction.do int indexOfSemicolon = uri.indexOf(";");//修正url的带;jsessionid 时找不到而且的bug uri = (indexOfSemicolon > -1) ? uri.substring(0, indexOfSemicolon) : uri; uri = dropExtension(uri, mapping);//删除扩展名,默认扩展名为action if (uri == null) { return null; } parseNameAndNamespace(uri, mapping, configManager);//匹配Action的name和namespace handleSpecialParameters(request, mapping);//去掉重复参数 //如果Action的name没有解析出来,直接返回     if (mapping.getName() == null) {       returnnull;     }     //下面处理形如testAction!method格式的请求路径     if (allowDynamicMethodCalls) {       // handle "name!method" convention.       String name = mapping.getName();       int exclamation = name.lastIndexOf("!");//!是Action名称和方法名的分隔符       if (exclamation != -1) {         mapping.setName(name.substring(0, exclamation));//提取左边为name         mapping.setMethod(name.substring(exclamation + 1));//提取右边的method       }     } return mapping; } 从代码中看出,getMapping()方法返回ActionMapping类型的对象,该对象包含三个参数:Action的name、namespace和要调用的方法method。   如果getMapping()方法返回ActionMapping对象为null,则FilterDispatcher认为用户请求不是Action,自然另当别论,FilterDispatcher会做一件非常有意思的事:如果请求以/struts开头,会自动查找在web.xml文件中配置的 packages初始化参数,就像下面这样:       struts2           org.apache.struts2.dispatcher.FilterDispatcher               packages       com.lizanhong.action              struts2           org.apache.struts2.dispatcher.FilterDispatcher               packages       com.lizanhong.action        FilterDispatcher会将com.lizanhong.action包下的文件当作静态资源处理,即直接在页面上显示文件内容,不过会忽略扩展名为class的文件。比如在com.lizanhong.action包下有一个aaa.txt的文本文件,其内容为“中华人民共和国”,访问 http://localhost:8081/Struts2Demo/struts/aaa.txt时会输出txt中的内容 FilterDispatcher.findStaticResource()方法 protectedvoid findStaticResource(String name, HttpServletRequest request, HttpServletResponse response) throws IOException {     if (!name.endsWith(".class")) {//忽略class文件       //遍历packages参数       for (String pathPrefix : pathPrefixes) {         InputStream is = findInputStream(name, pathPrefix);//读取请求文件流         if (is != null) {           ...           // set the content-type header           String contentType = getContentType(name);//读取内容类型           if (contentType != null) {             response.setContentType(contentType);//重新设置内容类型           }          ...           try {            //将读取到的文件流以每次复制4096个字节的方式循环输出             copy(is, response.getOutputStream());           } finally {             is.close();           }           return;         }       }     }   } protectedvoid findStaticResource(String name, HttpServletRequest request, HttpServletResponse response) throws IOException {     if (!name.endsWith(".class")) {//忽略class文件       //遍历packages参数       for (String pathPrefix : pathPrefixes) {         InputStream is = findInputStream(name, pathPrefix);//读取请求文件流         if (is != null) {           ...           // set the content-type header           String contentType = getContentType(name);//读取内容类型           if (contentType != null) {             response.setContentType(contentType);//重新设置内容类型           }          ...           try {            //将读取到的文件流以每次复制4096个字节的方式循环输出             copy(is, response.getOutputStream());           } finally {             is.close();           }           return;         }       }     }   } 如果用户请求的资源不是以/struts开头——可能是.jsp文件,也可能是.html文件,则通过过滤器链继续往下传送,直到到达请求的资源为止。 如果getMapping()方法返回有效的ActionMapping对象,则被认为正在请求某个Action,将调用 Dispatcher.serviceAction(request, response, servletContext, mapping)方法,该方法是处理Action的关键所在。 下面就来看serviceAction,这又回到全局变量dispatcher中了 //Load Action class for mapping and invoke the appropriate Action method, or go directly to the Result. public void serviceAction(HttpServletRequest request, HttpServletResponse response, ServletContext context, ActionMapping mapping) throws ServletException { //createContextMap方法主要把Application、Session、Request的key value值拷贝到Map中 Map extraContext = createContextMap(request, response, mapping, context); // If there was a previous value stack, then create a new copy and pass it in to be used by the new Action ValueStack stack = (ValueStack) request.getAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY); boolean nullStack = stack == null; if (nullStack) { ActionContext ctx = ActionContext.getContext(); if (ctx != null) { stack = ctx.getValueStack(); } } if (stack != null) { extraContext.put(ActionContext.VALUE_STACK, valueStackFactory.createValueStack(stack)); } String timerKey = "Handling request from Dispatcher"; try { UtilTimerStack.push(timerKey); String namespace = mapping.getNamespace(); String name = mapping.getName(); String method = mapping.getMethod(); Configuration config = configurationManager.getConfiguration(); //创建一个Action的代理对象,ActionProxyFactory是创建ActionProxy的工厂 //参考实现类:DefaultActionProxy和DefaultActionProxyFactory ActionProxy proxy = config.getContainer().getInstance(ActionProxyFactory.class).createActionProxy( namespace, name, method, extraContext, true, false); request.setAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY, proxy.getInvocation().getStack()); // if the ActionMapping says to go straight to a result, do it! //如果是Result,则直接转向,关于Result,ActionProxy,ActionInvocation下一讲中再分析 if (mapping.getResult() != null) { Result result = mapping.getResult(); result.execute(proxy.getInvocation()); } else { //执行Action proxy.execute(); } // If there was a previous value stack then set it back onto the request if (!nullStack) { request.setAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY, stack); } } catch (ConfigurationException e) { // WW-2874 Only log error if in devMode if(devMode) { LOG.error("Could not find action or result", e); } else { LOG.warn("Could not find action or result", e); } sendError(request, response, context, HttpServletResponse.SC_NOT_FOUND, e); } catch (Exception e) { sendError(request, response, context, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e); } finally { UtilTimerStack.pop(timerKey); } } 下面开始讲一下主菜ActionProxy了.在这之前最好先去了解一下动态Proxy的基本知识. ActionProxy是Action的一个代理类,也就是说Action的调用是通过ActionProxy实现的,其实就是调用了ActionProxy.execute()方法,而该方法又调用了ActionInvocation.invoke()方法。归根到底,最后调用的是DefaultActionInvocation.invokeAction()方法。 DefaultActionInvocation()->init()->createAction()。 最后通过调用ActionProxy.exute()-->ActionInvocation.invoke()-->Intercepter.intercept()-->ActionInvocation.invokeActionOnly()-->invokeAction() 这里的步骤是先由ActionProxyFactory创建ActionInvocation和ActionProxy. public ActionProxy createActionProxy(String namespace, String actionName, String methodName, Map extraContext, boolean executeResult, boolean cleanupContext) { ActionInvocation inv = new DefaultActionInvocation(extraContext, true); container.inject(inv); return createActionProxy(inv, namespace, actionName, methodName, executeResult, cleanupContext); } public ActionProxy createActionProxy(String namespace, String actionName, String methodName, Map extraContext, boolean executeResult, boolean cleanupContext) { ActionInvocation inv = new DefaultActionInvocation(extraContext, true); container.inject(inv); return createActionProxy(inv, namespace, actionName, methodName, executeResult, cleanupContext); } 下面先看DefaultActionInvocation的init方法 public void init(ActionProxy proxy) { this.proxy = proxy; Map contextMap = createContextMap(); // Setting this so that other classes, like object factories, can use the ActionProxy and other // contextual information to operate ActionContext actionContext = ActionContext.getContext(); if (actionContext != null) { actionContext.setActionInvocation(this); } //创建Action,struts2中每一个Request都会创建一个新的Action createAction(contextMap); if (pushAction) { stack.push(action); contextMap.put("action", action); } invocationContext = new ActionContext(contextMap); invocationContext.setName(proxy.getActionName()); // get a new List so we don't get problems with the iterator if someone changes the list List interceptorList = new ArrayList(proxy.getConfig().getInterceptors()); interceptors = interceptorList.iterator(); } protected void createAction(Map contextMap) { // load action String timerKey = "actionCreate: " + proxy.getActionName(); try { UtilTimerStack.push(timerKey); //默认为SpringObjectFactory:struts.objectFactory=spring.这里非常巧妙,在struts.properties中可以重写这个属性 //在前面BeanSelectionProvider中通过配置文件为ObjectFactory设置实现类 //这里以Spring为例,这里会调到SpringObjectFactory的buildBean方法,可以通过ApplicationContext的getBean()方法得到Spring的Bean action = objectFactory.buildAction(proxy.getActionName(), proxy.getNamespace(), proxy.getConfig(), contextMap); } catch (InstantiationException e) { throw new XWorkException("Unable to intantiate Action!", e, proxy.getConfig()); } catch (IllegalAccessException e) { throw new XWorkException("Illegal access to constructor, is it public?", e, proxy.getConfig()); } catch (Exception e) { ... } finally { UtilTimerStack.pop(timerKey); } if (actionEventListener != null) { action = actionEventListener.prepare(action, stack); } } //SpringObjectFactory public Object buildBean(String beanName, Map extraContext, boolean injectInternal) throws Exception { Object o = null; try { //SpringObjectFactory会通过web.xml中的context-param:contextConfigLocation自动注入ClassPathXmlApplicationContext o = appContext.getBean(beanName); } catch (NoSuchBeanDefinitionException e) { Class beanClazz = getClassInstance(beanName); o = buildBean(beanClazz, extraContext); } if (injectInternal) { injectInternalBeans(o); } return o; } public void init(ActionProxy proxy) { this.proxy = proxy; Map contextMap = createContextMap(); // Setting this so that other classes, like object factories, can use the ActionProxy and other // contextual information to operate ActionContext actionContext = ActionContext.getContext(); if (actionContext != null) { actionContext.setActionInvocation(this); } //创建Action,struts2中每一个Request都会创建一个新的Action createAction(contextMap); if (pushAction) { stack.push(action); contextMap.put("action", action); } invocationContext = new ActionContext(contextMap); invocationContext.setName(proxy.getActionName()); // get a new List so we don't get problems with the iterator if someone changes the list List interceptorList = new ArrayList(proxy.getConfig().getInterceptors()); interceptors = interceptorList.iterator(); } protected void createAction(Map contextMap) { // load action String timerKey = "actionCreate: " + proxy.getActionName(); try { UtilTimerStack.push(timerKey); //默认为SpringObjectFactory:struts.objectFactory=spring.这里非常巧妙,在struts.properties中可以重写这个属性 //在前面BeanSelectionProvider中通过配置文件为ObjectFactory设置实现类 //这里以Spring为例,这里会调到SpringObjectFactory的buildBean方法,可以通过ApplicationContext的getBean()方法得到Spring的Bean action = objectFactory.buildAction(proxy.getActionName(), proxy.getNamespace(), proxy.getConfig(), contextMap); } catch (InstantiationException e) { throw new XWorkException("Unable to intantiate Action!", e, proxy.getConfig()); } catch (IllegalAccessException e) { throw new XWorkException("Illegal access to constructor, is it public?", e, proxy.getConfig()); } catch (Exception e) { ... } finally { UtilTimerStack.pop(timerKey); } if (actionEventListener != null) { action = actionEventListener.prepare(action, stack); } } //SpringObjectFactory public Object buildBean(String beanName, Map extraContext, boolean injectInternal) throws Exception { Object o = null; try { //SpringObjectFactory会通过web.xml中的context-param:contextConfigLocation自动注入ClassPathXmlApplicationContext o = appContext.getBean(beanName); } catch (NoSuchBeanDefinitionException e) { Class beanClazz = getClassInstance(beanName); o = buildBean(beanClazz, extraContext); } if (injectInternal) { injectInternalBeans(o); } return o; } //接下来看看DefaultActionInvocation 的invoke方法 public String invoke() throws Exception { String profileKey = "invoke: "; try { UtilTimerStack.push(profileKey); if (executed) { throw new IllegalStateException("Action has already executed"); } //递归执行interceptor if (interceptors.hasNext()) { //interceptors是InterceptorMapping实际上是像一个像FilterChain一样的Interceptor链 //通过调用Invocation.invoke()实现递归牡循环 final InterceptorMapping interceptor = (InterceptorMapping) interceptors.next(); String interceptorMsg = "interceptor: " + interceptor.getName(); UtilTimerStack.push(interceptorMsg); try { //在每个Interceptor的方法中都会return invocation.invoke() resultCode = interceptor.getInterceptor().intercept(DefaultActionInvocation.this); } finally { UtilTimerStack.pop(interceptorMsg); } } else { //当所有interceptor都执行完,最后执行Action,invokeActionOnly会调用invokeAction()方法 resultCode = invokeActionOnly(); } // this is needed because the result will be executed, then control will return to the Interceptor, which will // return above and flow through again //在Result返回之前调用preResultListeners //通过executed控制,只执行一次 if (!executed) { if (preResultListeners != null) { for (Object preResultListener : preResultListeners) { PreResultListener listener = (PreResultListener) preResultListener; String _profileKey = "preResultListener: "; try { UtilTimerStack.push(_profileKey); listener.beforeResult(this, resultCode); } finally { UtilTimerStack.pop(_profileKey); } } } // now execute the result, if we're supposed to //执行Result if (proxy.getExecuteResult()) { executeResult(); } executed = true; } return resultCode; } finally { UtilTimerStack.pop(profileKey); } } //invokeAction protected String invokeAction(Object action,ActionConfig actionConfig)throws Exception{ String methodName = proxy.getMethod(); String timerKey = "invokeAction: " + proxy.getActionName(); try { UtilTimerStack.push(timerKey); boolean methodCalled = false; Object methodResult = null; Method method = null; try { //java反射机制得到要执行的方法 method = getAction().getClass().getMethod(methodName, new Class[0]); } catch (NoSuchMethodException e) { // hmm -- OK, try doXxx instead //如果没有对应的方法,则使用do+Xxxx来再次获得方法 try { String altMethodName = "do" + methodName.substring(0, 1).toUpperCase() + methodName.substring(1); method = getAction().getClass().getMethod(altMethodName, new Class[0]); } catch (NoSuchMethodException e1) { // well, give the unknown handler a shot if (unknownHandlerManager.hasUnknownHandlers()) { try { methodResult = unknownHandlerManager.handleUnknownMethod(action, methodName); methodCalled = true; } catch (NoSuchMethodException e2) { // throw the original one throw e; } } else { throw e; } } } //执行Method if (!methodCalled) { methodResult = method.invoke(action, new Object[0]); } //从这里可以看出可以Action的方法可以返回String去匹配Result,也可以直接返回Result类 if (methodResult instanceof Result) { this.explicitResult = (Result) methodResult; // Wire the result automatically container.inject(explicitResult); return null; } else { return (String) methodResult; } } catch (NoSuchMethodException e) { throw new IllegalArgumentException("The " + methodName + "() is not defined in action " + getAction().getClass() + ""); } catch (InvocationTargetException e) { // We try to return the source exception. Throwable t = e.getTargetException(); if (actionEventListener != null) { String result = actionEventListener.handleException(t, getStack()); if (result != null) { return result; } } if (t instanceof Exception) { throw (Exception) t; } else { throw e; } } finally { UtilTimerStack.pop(timerKey); } } //接下来看看DefaultActionInvocation 的invoke方法 public String invoke() throws Exception { String profileKey = "invoke: "; try { UtilTimerStack.push(profileKey); if (executed) { throw new IllegalStateException("Action has already executed"); } //递归执行interceptor if (interceptors.hasNext()) { //interceptors是InterceptorMapping实际上是像一个像FilterChain一样的Interceptor链 //通过调用Invocation.invoke()实现递归牡循环 final InterceptorMapping interceptor = (InterceptorMapping) interceptors.next(); String interceptorMsg = "interceptor: " + interceptor.getName(); UtilTimerStack.push(interceptorMsg); try { //在每个Interceptor的方法中都会return invocation.invoke() resultCode = interceptor.getInterceptor().intercept(DefaultActionInvocation.this); } finally { UtilTimerStack.pop(interceptorMsg); } } else { //当所有interceptor都执行完,最后执行Action,invokeActionOnly会调用invokeAction()方法 resultCode = invokeActionOnly(); } // this is needed because the result will be executed, then control will return to the Interceptor, which will // return above and flow through again //在Result返回之前调用preResultListeners //通过executed控制,只执行一次 if (!executed) { if (preResultListeners != null) { for (Object preResultListener : preResultListeners) { PreResultListener listener = (PreResultListener) preResultListener; String _profileKey = "preResultListener: "; try { UtilTimerStack.push(_profileKey); listener.beforeResult(this, resultCode); } finally { UtilTimerStack.pop(_profileKey); } } } // now execute the result, if we're supposed to //执行Result if (proxy.getExecuteResult()) { executeResult(); } executed = true; } return resultCode; } finally { UtilTimerStack.pop(profileKey); } } //invokeAction protected String invokeAction(Object action,ActionConfig actionConfig)throws Exception{ String methodName = proxy.getMethod(); String timerKey = "invokeAction: " + proxy.getActionName(); try { UtilTimerStack.push(timerKey); boolean methodCalled = false; Object methodResult = null; Method method = null; try { //java反射机制得到要执行的方法 method = getAction().getClass().getMethod(methodName, new Class[0]); } catch (NoSuchMethodException e) { // hmm -- OK, try doXxx instead //如果没有对应的方法,则使用do+Xxxx来再次获得方法 try { String altMethodName = "do" + methodName.substring(0, 1).toUpperCase() + methodName.substring(1); method = getAction().getClass().getMethod(altMethodName, new Class[0]); } catch (NoSuchMethodException e1) { // well, give the unknown handler a shot if (unknownHandlerManager.hasUnknownHandlers()) { try { methodResult = unknownHandlerManager.handleUnknownMethod(action, methodName); methodCalled = true; } catch (NoSuchMethodException e2) { // throw the original one throw e; } } else { throw e; } } } //执行Method if (!methodCalled) { methodResult = method.invoke(action, new Object[0]); } //从这里可以看出可以Action的方法可以返回String去匹配Result,也可以直接返回Result类 if (methodResult instanceof Result) { this.explicitResult = (Result) methodResult; // Wire the result automatically container.inject(explicitResult); return null; } else { return (String) methodResult; } } catch (NoSuchMethodException e) { throw new IllegalArgumentException("The " + methodName + "() is not defined in action " + getAction().getClass() + ""); } catch (InvocationTargetException e) { // We try to return the source exception. Throwable t = e.getTargetException(); if (actionEventListener != null) { String result = actionEventListener.handleException(t, getStack()); if (result != null) { return result; } } if (t instanceof Exception) { throw (Exception) t; } else { throw e; } } finally { UtilTimerStack.pop(timerKey); } } action执行完了,还要根据ResultConfig返回到view,也就是在invoke方法中调用executeResult方法。 private void executeResult() throws Exception { //根据ResultConfig创建Result result = createResult(); String timerKey = "executeResult: " + getResultCode(); try { UtilTimerStack.push(timerKey); if (result != null) { //开始执行Result, //可以参考Result的实现,如用了比较多的ServletDispatcherResult,ServletActionRedirectResult,ServletRedirectResult result.execute(this); } else if (resultCode != null && !Action.NONE.equals(resultCode)) { throw new ConfigurationException("No result defined for action " + getAction().getClass().getName() + " and result " + getResultCode(), proxy.getConfig()); } else { if (LOG.isDebugEnabled()) { LOG.debug("No result returned for action " + getAction().getClass().getName() + " at " + proxy.getConfig().getLocation()); } } } finally { UtilTimerStack.pop(timerKey); } } public Result createResult() throws Exception { //如果Action中直接返回的Result类型,在invokeAction()保存在explicitResult if (explicitResult != null) { Result ret = explicitResult; explicitResult = null; return ret; } //返回的是String则从config中得到当前Action的Results列表 ActionConfig config = proxy.getConfig(); Map results = config.getResults(); ResultConfig resultConfig = null; synchronized (config) { try { //通过返回的String来匹配resultConfig resultConfig = results.get(resultCode); } catch (NullPointerException e) { // swallow } if (resultConfig == null) { // If no result is found for the given resultCode, try to get a wildcard '*' match. //如果找不到对应name的ResultConfig,则使用name为*的Result //说明可以用*通配所有的Result resultConfig = results.get("*"); } } if (resultConfig != null) { try { //创建Result return objectFactory.buildResult(resultConfig, invocationContext.getContextMap()); } catch (Exception e) { LOG.error("There was an exception while instantiating the result of type " + resultConfig.getClassName(), e); throw new XWorkException(e, resultConfig); } } else if (resultCode != null && !Action.NONE.equals(resultCode) && unknownHandlerManager.hasUnknownHandlers()) { return unknownHandlerManager.handleUnknownResult(invocationContext, proxy.getActionName(), proxy.getConfig(), resultCode); } return null; } public Result buildResult(ResultConfig resultConfig, Map extraContext) throws Exception { String resultClassName = resultConfig.getClassName(); Result result = null; if (resultClassName != null) { //buildBean中会用反射机制Class.newInstance来创建bean result = (Result) buildBean(resultClassName, extraContext); Map params = resultConfig.getParams(); if (params != null) { for (Map.Entry paramEntry : params.entrySet()) { try { //reflectionProvider参见OgnlReflectionProvider; //resultConfig.getParams()就是result配置文件里所配置的参数 //setProperties方法最终调用的是Ognl类的setValue方法 //这句其实就是把param名值设置到根对象result上 reflectionProvider.setProperty(paramEntry.getKey(), paramEntry.getValue(), result, extraContext, true); } catch (ReflectionException ex) { if (LOG.isErrorEnabled()) LOG.error("Unable to set parameter [#0] in result of type [#1]", ex, paramEntry.getKey(), resultConfig.getClassName()); if (result instanceof ReflectionExceptionHandler) { ((ReflectionExceptionHandler) result).handle(ex); } } } } } return result; }

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