本文主要有三个步骤 1、用户登录后建立websocket连接，默认选择websocket连接，如果浏览器不支持，则使用sockjs进行模拟连接 2、建立连接后，服务端返回该用户的未读消息 3、服务端进行相关操作后，推送给某一个用户或者所有用户新消息 相关环境 Spring4.0.6(要选择4.0+),tomcat7.0.55

Websocet服务端实现

WebSocketConfig.java

@Configuration  @EnableWebMvc  @EnableWebSocket  public class WebSocketConfig extends WebMvcConfigurerAdapter implements WebSocketConfigurer {      @Override      public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {          registry.addHandler(systemWebSocketHandler(),"/webSocketServer").addInterceptors(new WebSocketHandshakeInterceptor());            registry.addHandler(systemWebSocketHandler(), "/sockjs/webSocketServer").addInterceptors(new WebSocketHandshakeInterceptor())                  .withSockJS();      }        @Bean      public WebSocketHandler systemWebSocketHandler(){          return new SystemWebSocketHandler();      }    }

不要忘记在springmvc的配置文件中配置对此类的自动扫描

<context:component-scan base-package="com.ldl.origami.websocket" />

<p>@Configuration </p> <p>@EnableWebMvc
@EnableWebSocket
这三个大致意思是使这个类支持以@Bean的方式加载bean，并且支持springmvc和websocket，不是很准确大致这样，试了一下<span>@EnableWebMvc不加也没什么影响，<span>@Configuration本来就支持springmvc的自动扫描</span></span> </p>

registry.addHandler(systemWebSocketHandler(),"/webSocketServer").addInterceptors(new WebSocketHandshakeInterceptor())

用来注册websocket server实现类，第二个参数是访问websocket的地址

registry.addHandler(systemWebSocketHandler(), "/sockjs/webSocketServer").addInterceptors(new WebSocketHandshakeInterceptor())                  .withSockJS();      }

这个是使用Sockjs的注册方法

首先SystemWebSocketHandler.java

public class SystemWebSocketHandler implements WebSocketHandler {        private static final Logger logger;        private static final ArrayList<WebSocketSession> users;        static {          users = new ArrayList<>();          logger = LoggerFactory.getLogger(SystemWebSocketHandler.class);      }        @Autowired      private WebSocketService webSocketService;        @Override      public void afterConnectionEstablished(WebSocketSession session) throws Exception {          logger.debug("connect to the websocket success......");          users.add(session);          String userName = (String) session.getAttributes().get(Constants.WEBSOCKET_USERNAME);          if(userName!= null){              //查询未读消息              int count = webSocketService.getUnReadNews((String) session.getAttributes().get(Constants.WEBSOCKET_USERNAME));                session.sendMessage(new TextMessage(count + ""));          }      }        @Override      public void handleMessage(WebSocketSession session, WebSocketMessage<?> message) throws Exception {            //sendMessageToUsers();      }        @Override      public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {          if(session.isOpen()){              session.close();          }          logger.debug("websocket connection closed......");          users.remove(session);      }        @Override      public void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception {          logger.debug("websocket connection closed......");          users.remove(session);      }        @Override      public boolean supportsPartialMessages() {          return false;      }        /**       * 给所有在线用户发送消息       *       * @param message       */      public void sendMessageToUsers(TextMessage message) {          for (WebSocketSession user : users) {              try {                  if (user.isOpen()) {                      user.sendMessage(message);                  }              } catch (IOException e) {                  e.printStackTrace();              }          }      }        /**       * 给某个用户发送消息       *       * @param userName       * @param message       */      public void sendMessageToUser(String userName, TextMessage message) {          for (WebSocketSession user : users) {              if (user.getAttributes().get(Constants.WEBSOCKET_USERNAME).equals(userName)) {                  try {                      if (user.isOpen()) {                          user.sendMessage(message);                      }                  } catch (IOException e) {                      e.printStackTrace();                  }                  break;              }          }      }  }

相关内容大家一看就能明白，就不多解释了

然后WebSocketHandshakeInterceptor.java

public class WebSocketHandshakeInterceptor implements HandshakeInterceptor {        private static Logger logger = LoggerFactory.getLogger(HandshakeInterceptor.class);      @Override      public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Map<String, Object                  > attributes) throws Exception {          if (request instanceof ServletServerHttpRequest) {              ServletServerHttpRequest servletRequest = (ServletServerHttpRequest) request;              HttpSession session = servletRequest.getServletRequest().getSession(false);              if (session != null) {                  //使用userName区分WebSocketHandler，以便定向发送消息                  String userName = (String) session.getAttribute(Constants.SESSION_USERNAME);                  attributes.put(Constants.WEBSOCKET_USERNAME,userName);              }          }          return true;      }        @Override      public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Exception exception) {        }  }

这个的主要作用是取得当前请求中的用户名，并且保存到当前的WebSocketHandler中，以便确定WebSocketHandler所对应的用户，具体可参考HttpSessionHandshakeInterceptor

用户登录建立websocket连接

index.jsp

<script type="text/javascript" src="http://localhost:8080/Origami/websocket/sockjs-0.3.min.js"></script>          <script>              var websocket;              if ('WebSocket' in window) {                  websocket = new WebSocket("ws://localhost:8080/Origami/webSocketServer");              } else if ('MozWebSocket' in window) {                  websocket = new MozWebSocket("ws://localhost:8080/Origami/webSocketServer");              } else {                  websocket = new SockJS("http://localhost:8080/Origami/sockjs/webSocketServer");              }              websocket.onopen = function (evnt) {              };              websocket.onmessage = function (evnt) {                  $("#msgcount").html("(<font color='red'>"+evnt.data+"</font>)")              };              websocket.onerror = function (evnt) {              };              websocket.onclose = function (evnt) {              }            </script>

使用sockjs时要注意

1、这两个的写法

<script type="text/javascript" src="http://localhost:8080/Origami/websocket/sockjs-0.3.min.js"></script>

websocket = new SockJS("http://localhost:8080/Origami/sockjs/webSocketServer");

2、web.xml中

<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"   xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_1.xsd">

version

web-app_3_1.xsd

这两个的版本都要是3.0+

然后在这个servlet中加入

<async-supported>true</async-supported>

<servlet>    <servlet-name>appServlet</servlet-name>    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>    <init-param>     <param-name>contextConfigLocation</param-name>     <param-value>classpath*:servlet-context.xml</param-value>    </init-param>    <load-on-startup>1</load-on-startup>          <async-supported>true</async-supported>   </servlet>

然后所有的filter中也加入

<async-supported>true</async-supported>

3、添加相关依赖

<dependency>              <groupId>com.fasterxml.jackson.core</groupId>              <artifactId>jackson-annotations</artifactId>              <version>2.3.0</version>          </dependency>          <dependency>              <groupId>com.fasterxml.jackson.core</groupId>              <artifactId>jackson-core</artifactId>              <version>2.3.1</version>          </dependency>          <dependency>              <groupId>com.fasterxml.jackson.core</groupId>              <artifactId>jackson-databind</artifactId>              <version>2.3.3</version>          </dependency>

好了，现在websocket可以正常建立起来了

返回用户未读的消息

当连接建立后，会进入SystemWebSocketHandler的afterConnectionEstablished方法，代码看上边，取出WebSocketHandshakeInterceptor中保存的用户名

查询信息后使用session.sendMessage(new TextMessage(count + ""));返回给用户，从哪来回哪去

服务端推送消息给用户

@Controller  public class AdminController {        static Logger logger = LoggerFactory.getLogger(AdminController.class);        @Autowired(required = false)      private AdminService adminService;        @Bean      public SystemWebSocketHandler systemWebSocketHandler() {          return new SystemWebSocketHandler();      }          @RequestMapping("/auditing")      @ResponseBody      public String auditing(HttpServletRequest request){          //无关代码都省略了          int unReadNewsCount = adminService.getUnReadNews(username);          systemWebSocketHandler().sendMessageToUser(username, new TextMessage(unReadNewsCount + ""));          return result;      }  }

在这里可以使用sendMessageToUser给某个用户推送信息，也可以使用sendMessageToUsers给所有用户推送信息

来自：http://my.oschina.net/ldl123292/blog/304360