<h2>概述</h2>    <p>Butterknife是供职于Square公司的JakeWharton大神开发的开源库，使用这个库，在AS中搭配 <a href="/misc/goto?guid=4959671792203787710" rel="nofollow,noindex">Android</a> ButterKnife Zelezny插件，可以大大提高开发的效率，从此摆脱繁琐的findViewById(int id)，也不用自己手动@bind(int id) ， 直接用插件生成即可。本篇文章将对Butterknife进行深入解析。</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/eac77eea8e60f3d81fe3f490e325daba.png"></p>    <p>ButterKnife有以下优点：</p>    <p>1、强大的View绑定和Click事件处理功能，简化代码，提升开发效率</p>    <p>2、方便的处理Adapter里的ViewHolder绑定问题</p>    <p>3、运行时不会影响APP效率，使用配置方便</p>    <p>4、代码清晰，可读性强</p>    <h2>如何导入ButterKnife</h2>    <p>在项目的build.grade文件中进行如下配置：</p>    <pre>  <code class="language-java">buildscript {      repositories {          jcenter()          mavenCentral()          maven {              url "https://plugins.gradle.org/m2/"          }      }      dependencies {          classpath 'com.android.tools.build:gradle:2.2.0'          //这里配置 apt 供butterknife使用          classpath 'com.neenbedankt.gradle.plugins:android-apt:1.8'        }  }</code></pre>    <p>例如：</p>    <pre>  <code class="language-java">buildscript {      repositories {          jcenter()          mavenCentral()          maven {              url "https://plugins.gradle.org/m2/"          }        }        dependencies {          classpath 'com.android.tools.build:gradle:2.2.2'          classpath 'com.neenbedankt.gradle.plugins:android-apt:1.8'      }  }    allprojects {      repositories {          jcenter()      }  }    task clean(type: Delete) {      delete rootProject.buildDir  }</code></pre>    <p>在app的build.grade文件中进行如下配置：</p>    <pre>  <code class="language-java">apply plugin: 'com.android.application'  apply plugin: 'com.neenbedankt.android-apt'    android{...}    dependencies {      //视图绑定 butterknife      compile 'com.jakewharton:butterknife:8.4.0'      apt 'com.jakewharton:butterknife-compiler:8.4.0'  }</code></pre>    <p>例如：</p>    <pre>  <code class="language-java">apply plugin: 'com.android.application'  apply plugin: 'android-apt'    android {      compileSdkVersion 24      buildToolsVersion "24.0.3"        defaultConfig {            minSdkVersion 14          targetSdkVersion 24          versionCode 1          versionName "1.0"      }      buildTypes {          release {              minifyEnabled false              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'          }      }  }    dependencies {      compile fileTree(dir: 'libs', include: ['*.jar'])        compile 'com.jakewharton:butterknife:8.4.0'      apt 'com.jakewharton:butterknife-compiler:8.4.0'  }</code></pre>    <h2>如何使用ButterKnife</h2>    <p>1) 由于每次都要在Activity中的onCreate绑定Activity，所以个人建议写一个BaseActivity完成绑定，子类继承即可</p>    <p>注：ButterKnife.bind(this)；绑定Activity 必须在setContentView之后：</p>    <p>实现如下（FragmentActivity 实现一样）：</p>    <pre>  <code class="language-java">public abstract class BaseActivity extends Activity {        public abstract int getContentViewId();          @Override        protected void onCreate(Bundle savedInstanceState) {            super.onCreate(savedInstanceState);            setContentView(getContentViewId());            ButterKnife.bind(this);            initAllMembersView(savedInstanceState);        }          protected abstract void initAllMembersView(Bundle savedInstanceState);          @Override        protected void onDestroy() {            super.onDestroy();            ButterKnife.unbind(this);//解除绑定，官方文档只对fragment做了解绑        }    }</code></pre>    <p>2) 绑定fragment</p>    <pre>  <code class="language-java">public abstract class BaseFragment extends Fragment {        public abstract int getContentViewId();        protected Context context;        protected View mRootView;          @Nullable        @Override        public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {            mRootView =inflater.inflate(getContentViewId(),container,false);            ButterKnife.bind(this,mRootView);//绑定framgent            this.context = getActivity();            initAllMembersView(savedInstanceState);            return mRootView;        }          protected abstract void initAllMembersView(Bundle savedInstanceState);          @Override        public void onDestroyView() {            super.onDestroyView();            ButterKnife.unbind(this);//解绑        }    }</code></pre>    <p>3) 控件id 注解： @BindView（）</p>    <pre>  <code class="language-java">package com.myl.test;    import android.support.v7.app.AppCompatActivity;  import android.os.Bundle;  import android.widget.Button;    import butterknife.BindView;  import butterknife.ButterKnife;    public class ButterknifeActivity extends AppCompatActivity {        @BindView( R.id.button1 )      public Button button1 ;        // 注意：button 的修饰类型不能是：private 或者 static 。 否则会报错：错误: @BindView fields must not be private or static. (com.myl.test.ButterknifeActivity.button1)        @Override      protected void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.activity_butterknife);          //绑定activity          ButterKnife.bind( this ) ;            button1.setText( "I am a button ");      }  }</code></pre>    <p>4) 多个控件id 注解： @BindViews（）</p>    <pre>  <code class="language-java">package com.myl.test;    import android.support.v7.app.AppCompatActivity;  import android.os.Bundle;  import android.widget.Button;  import java.util.List;  import butterknife.BindViews;  import butterknife.ButterKnife;    public class Main2Activity extends AppCompatActivity {        @BindViews({ R.id.button1  , R.id.button2 ,  R.id.button3 })      public List<Button> buttonList ;        @Override      protected void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.activity_main2);            ButterKnife.bind(this);            buttonList.get( 0 ).setText( "hello 1 ");          buttonList.get( 1 ).setText( "hello 2 ");          buttonList.get( 2 ).setText( "hello 3 ");      }  }</code></pre>    <p>5) @BindString() ：绑定string 字符串</p>    <pre>  <code class="language-java">package com.myl.test;    import android.os.Bundle;  import android.support.v7.app.AppCompatActivity;  import android.widget.Button;    import butterknife.BindString;  import butterknife.BindView;  import butterknife.ButterKnife;    public class ButterknifeActivity extends AppCompatActivity {        @BindView( R.id.button1 ) //绑定button 控件      public Button button1 ;        @BindString( R.string.app_name )  //绑定string 字符串      String meg;        @Override      protected void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.activity_butterknife);            //绑定activity          ButterKnife.bind( this ) ;            button1.setText( meg );      }  }</code></pre>    <p>6) @BindArray() : 绑定string里面array数组</p>    <pre>  <code class="language-java"><resources>      <string name="app_name">校园助手</string>        <string-array name="city">          <item>东莞市</item>          <item>广州市</item>          <item>珠海市</item>          <item>肇庆市</item>          <item>深圳市</item>      </string-array>    </resources>  -----------------------------------------------------------------  package com.myl.test;    import android.os.Bundle;  import android.support.v7.app.AppCompatActivity;  import android.widget.Button;    import butterknife.BindArray;  import butterknife.BindView;  import butterknife.ButterKnife;    public class ButterknifeActivity extends AppCompatActivity {        @BindView( R.id.button1 ) //绑定button 控件      public Button button1 ;        @BindArray(R.array.city )  //绑定string里面array数组      String [] citys ;        @Override      protected void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.activity_butterknife);            //绑定activity          ButterKnife.bind( this ) ;            button1.setText( citys[0] );      }  }</code></pre>    <p>7) @BindBitmap( ) : 绑定Bitmap 资源</p>    <pre>  <code class="language-java">package com.myl.test;    import android.graphics.Bitmap;  import android.os.Bundle;  import android.support.v7.app.AppCompatActivity;  import android.widget.ImageView;    import butterknife.BindBitmap;  import butterknife.BindView;  import butterknife.ButterKnife;    public class ButterknifeActivity extends AppCompatActivity {        @BindView( R.id.imageView ) //绑定ImageView 控件      public ImageView imageView ;        @BindBitmap( R.mipmap.wifi )  //绑定Bitmap 资源      public Bitmap wifi_bitmap ;        @Override      protected void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.activity_butterknife);            //绑定activity          ButterKnife.bind( this ) ;            imageView.setImageBitmap( wifi_bitmap );      }  }</code></pre>    <p>8) @BindColor( ) : 绑定一个颜色值</p>    <pre>  <code class="language-java">package com.myl.test;    import android.os.Bundle;  import android.support.v7.app.AppCompatActivity;  import android.widget.Button;    import butterknife.BindColor;  import butterknife.BindView;  import butterknife.ButterKnife;    public class ButterknifeActivity extends AppCompatActivity {        @BindView( R.id.button1 )  //绑定一个控件      public Button button1 ;        @BindColor( R.color.colorAccent ) int black ;  //绑定一个颜色值        @Override      protected void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.activity_butterknife);            //绑定activity          ButterKnife.bind( this ) ;            button1.setTextColor(  black );        }  }</code></pre>    <p>9) Adapter ViewHolder 绑定</p>    <pre>  <code class="language-java">public class TestAdapter extends BaseAdapter {        private List<String> list;        private Context context;          public TestAdapter(Context context, List<String> list) {            this.list = list;            this.context = context;        }          @Override        public int getCount() {            return list==null ? 0 : list.size();        }          @Override        public Object getItem(int position) {            return list.get(position);        }          @Override        public long getItemId(int position) {            return position;        }          @Override        public View getView(int position, View convertView, ViewGroup parent) {            ViewHolder holder;            if (convertView == null) {                convertView = LayoutInflater.from(context).inflate(R.layout.layout_list_item, null);                holder = new ViewHolder(convertView);                convertView.setTag(holder);            } else {                holder = (ViewHolder) convertView.getTag();            }            holder.textview.setText("item=====" + position);            return convertView;        }          static class ViewHolder {            @Bind(R.id.hello_world)            TextView textview;              public ViewHolder(View view) {                ButterKnife.bind(this, view);            }        }    }</code></pre>    <p>10) 点击事件的绑定：不用声明view，不用setOnClickLisener（）就可以绑定点击事件</p>    <p>a. 直接绑定一个方法</p>    <pre>  <code class="language-java">@OnClick(R.id.submit)    public void submit(View view) {      // TODO submit data to server...    }</code></pre>    <p>b. 所有监听方法的参数是可选的</p>    <pre>  <code class="language-java">@OnClick(R.id.submit)    public void submit() {      // TODO submit data to server...    }</code></pre>    <p>c. 定义一个特定类型，它将自动被转换</p>    <pre>  <code class="language-java">@OnClick(R.id.submit)    public void sayHi(Button button) {      button.setText("Hello!");    }</code></pre>    <p>d. 多个view统一处理同一个点击事件，很方便，避免抽方法重复调用的麻烦</p>    <pre>  <code class="language-java">@OnClick({ R.id.door1, R.id.door2, R.id.door3 })    public void pickDoor(DoorView door) {      if (door.hasPrizeBehind()) {        Toast.makeText(this, "You win!", LENGTH_SHORT).show();      } else {        Toast.makeText(this, "Try again", LENGTH_SHORT).show();      }    }</code></pre>    <p>e. 自定义view可以绑定自己的监听，不指定id</p>    <pre>  <code class="language-java">public class FancyButton extends Button {      @OnClick      public void onClick() {        // TODO do something!      }    }</code></pre>    <p>f. 给EditText加addTextChangedListener（即添加多回调方法的监听的使用方法），利用指定回调，实现想回调的方法即可，哪个注解不会用点进去看下源码上的注释</p>    <pre>  <code class="language-java">@OnTextChanged(value = R.id.mobileEditText, callback = OnTextChanged.Callback.BEFORE_TEXT_CHANGED)    void beforeTextChanged(CharSequence s, int start, int count, int after) {      }    @OnTextChanged(value = R.id.mobileEditText, callback = OnTextChanged.Callback.TEXT_CHANGED)    void onTextChanged(CharSequence s, int start, int before, int count) {      }    @OnTextChanged(value = R.id.mobileEditText, callback = OnTextChanged.Callback.AFTER_TEXT_CHANGED)    void afterTextChanged(Editable s) {      }</code></pre>    <h2>代码混淆</h2>    <pre>  <code class="language-java">-keep class butterknife.** { *; }    -dontwarn butterknife.internal.**    -keep class **$$ViewBinder { *; }      -keepclasseswithmembernames class * {        @butterknife.* <fields>;    }      -keepclasseswithmembernames class * {        @butterknife.* <methods>;    }</code></pre>    <h2>Zelezny插件的使用</h2>    <p>在AndroidStudio->File->Settings->Plugins->搜索Zelezny下载添加就行 ，可以快速生成对应组件的实例对象，不用手动写。使用时，在要导入注解的Activity 或 Fragment 或 ViewHolder的layout资源代码上，右键——>Generate——Generate ButterKnife Injections，然后就出现如图的选择框。</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/84b66a1c0caee9c008da2a266095c9a7.gif"></p>    <h2>ButterKnife实现原理</h2>    <p>对ButterKnife有过了解人 ， 注入字段的方式是使用注解@BindView(R.id.tv_account_name)，但首先我们需要在Activity声明注入ButterKnife.bind(Activity activity) 。我们知道，注解分为好几类， 有在源码生效的注解，有在类文件生成时生效的注解，有在运行时生效的注解。分别为RetentionPolicy.SOURCE，RetentionPolicy.CLASS，RetentionPolicy.RUNTIME ，其中以RetentionPolicy.RUNTIME最为消耗性能。而ButterKnife使用的则是编译器时期注入，在使用的时候，需要配置classpath ‘com.neenbedankt.gradle.plugins:android-apt:1.8’ ， 这个配置说明，在编译的时候，进行注解处理。要对注解进行处理，则需要继承AbstractProcessor ， 在boolean process(Set</p>    <h2>ButterKnife实现方式</h2>    <p>知晓了注解可以在编译的时候进行处理，那么，我们就可以得到注解的字段属性与所在类 ， 进而生成注入文件，生成一个注入类的内部类，再进行字段处理 ， 编译之后就会合并到注入类中，达到植入新代码段的目的。例如：我们注入@VInjector(R.id.tv_show) TextView tvShow;我们就可以得到tvShow这个变量与R.id.tv_show这个id的值，然后进行模式化处理injectObject.tvShow = injectObject.findViewById(R.id.tv_show); ，再将代码以内部类的心事加入到组件所在的类中 ， 完成一次DI（注入） 。</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/6ce06e3e9ea439a97486fdc5b8e8f96a.png"></p>    <p>a) 首先创建一个视图注解</p>    <p>b) 创建一个注解处理器，用来得到注解的属性与所属类</p>    <p>c) 解析注解，分离组合Class与属性</p>    <p>d) 组合Class与属性，生成新的Java File</p>    <p>APT生成的Java File ， 以及模式代码</p>    <p style="text-align:center"><img src="https://simg.open-open.com/show/6f304007bc677577257a8d2be23048bb.png"></p>    <p>使用Javac ， 编译时期生成注入类的子类</p>    <h2>项目UML图</h2>    <p><img src="https://simg.open-open.com/show/a259b207364b403398cf160ea3d4802a.jpg"></p>    <p>简要说明：</p>    <p>主要类：</p>    <p>VInjectProcessor —-> 注解处理器 ， 需要配置注解处理器</p>    <pre>  <code class="language-java">resources          - META-INF                - services                      - javax.annotation.processing.Processor</code></pre>    <p>Processor内容：</p>    <pre>  <code class="language-java">com.myl.viewinject.apt.VInjectProcessor   # 指定处理器全类名</code></pre>    <p style="text-align:center"><img src="https://simg.open-open.com/show/4aa2c4137eabe620bc33a042827a96ac.png"></p>    <p>VInjectHandler —-> 注解处理类 ， 主要进行注入类与注解字段进行解析与封装，将同类的字段使用map集合进行映射。exp: Map</p>    <h2>自定义ButterKnife具体实现</h2>    <p>一 ， 创建注解 , 对视图进行注解，R.id.xxx ， 所以注解类型是int类型</p>    <pre>  <code class="language-java">/**   * Created by myl on 2016/11/21.   *   * View inject   * 字段注入注解，可以新建多个注解，再通过AnnotationProcessor进行注解处理   * RetentionPolicy.CLASS ，在编译的时候进行注解 。我们需要在生成.class文件的时候需要进行处理   */    @Retention(RetentionPolicy.CLASS)  @Target(ElementType.FIELD)  public @interface VInjector {      int value();  }</code></pre>    <p>二， 注解处理器 关于注解处理器配置，上面已经做了说明</p>    <pre>  <code class="language-java">/**   * Created by myl on 2016/11/21.   *   * Inject in View annotation processor   *   * 需要在配置文件中指定处理类 resources/META-INF/services/javax.annotation.processing.Processor   * com.myl.viewinject.apt.VInjectProcessor   */    @SupportedAnnotationTypes("com.myl.viewinject.annotation.VInjector")  @SupportedSourceVersion(SourceVersion.RELEASE_6)  public class VInjectProcessor extends AbstractProcessor {        List<IAnnotationHandler> mAnnotationHandler = new ArrayList<>();      Map<String,List<VariableElement>> mHandleAnnotationMap = new HashMap<>();      private IGenerateAdapter mGenerateAdapter;        @Override      public synchronized void init(ProcessingEnvironment processingEnv) {          super.init(processingEnv);          // init annotation handler , add handler          registerHandler(new VInjectHandler());            // init generate adapter          mGenerateAdapter = new ViewGenerateAdapter(processingEnv);        }        /*可以有多个处理*/      protected void registerHandler(IAnnotationHandler handler) {          mAnnotationHandler.add(handler);      }        // annotation into process run      @Override      public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {            for (IAnnotationHandler handler : mAnnotationHandler) {              // attach environment , 关联环境              handler.attachProcessingEnvironment(processingEnv);              // handle annotation 处理注解 ，得到注解类的属性列表              mHandleAnnotationMap.putAll(handler.handleAnnotation(roundEnv));          }          // 生成辅助类          mGenerateAdapter.generate(mHandleAnnotationMap);          // 表示处理          return true;      }  }</code></pre>    <p>对得到的注解进行处理 ， 主要是进行注解类型与属性进行分离合并处理，因为一个类有多个属性，所以采用map集合，进行存储，数据结构为：Map</p>    <pre>  <code class="language-java">/**   * Created by myl on 2016/11/21.   *   * 注解处理实现 , 解析VInjector注解属性   */  public class VInjectHandler implements IAnnotationHandler {        private ProcessingEnvironment mProcessingEnvironment;        @Override      public void attachProcessingEnvironment(ProcessingEnvironment environment) {              this.mProcessingEnvironment = environment;      }        @Override      public Map<String, List<VariableElement>> handleAnnotation(RoundEnvironment roundEnvironment) {          Map<String,List<VariableElement>> map = new HashMap<>();          /*获取一个类中带有VInjector注解的属性列表*/          Set<? extends Element> elements = roundEnvironment.getElementsAnnotatedWith(VInjector.class);          for (Element element : elements) {              VariableElement variableElement = (VariableElement) element;              /*获取类名 ，将类目与属性配对，一个类，对于他的属性列表*/              String className = getFullClassName(variableElement);              List<VariableElement> cacheElements = map.get(className);              if (cacheElements == null) {                  cacheElements = new ArrayList<>();                  map.put(className,cacheElements);              }              cacheElements.add(variableElement);          }            return map;      }        /**       * 获取注解属性的完整类名       * @param variableElement       */      private String getFullClassName(VariableElement variableElement) {          TypeElement typeElement = (TypeElement) variableElement.getEnclosingElement();          String packageName = AnnotationUtils.getPackageName(mProcessingEnvironment,typeElement);          return packageName+"."+typeElement.getSimpleName().toString();      }  }</code></pre>    <p>生成Java File ， 根据获取的属性与类，创建一个注入类的内部类</p>    <pre>  <code class="language-java">/**   * Created by myl on 2016/11/21.   *   * 生成View注解辅助类   */  public class ViewGenerateAdapter extends AbstractGenerateAdapter {        public ViewGenerateAdapter(ProcessingEnvironment processingEnvironment) {          super(processingEnvironment);      }        @Override      protected void generateImport(Writer writer, InjectInfo injectInfo) throws IOException {          writer.write("package "+injectInfo.packageName+";");          writer.write("\n\n");          writer.write("import  com.zeno.viewinject.adapter.IVInjectorAdapter;");          writer.write("\n\n");          writer.write("import  com.zeno.viewinject.utils.ViewFinder;");          writer.write("\n\n\n");          writer.write("/* This class file is generated by ViewInject , do not modify */");          writer.write("\n");          writer.write("public class "+injectInfo.newClassName+" implements IVInjectorAdapter<"+injectInfo.className+"> {");          writer.write("\n\n");          writer.write("public void injects("+injectInfo.className+" target) {");          writer.write("\n");      }        @Override      protected void generateField(Writer writer, VariableElement variableElement, InjectInfo injectInfo) throws IOException {          VInjector vInjector = variableElement.getAnnotation(VInjector.class);          int resId = vInjector.value();          String fieldName = variableElement.getSimpleName().toString();          writer.write("\t\ttarget."+fieldName+" = ViewFinder.findViewById(target,"+resId+");");          writer.write("\n");      }        @Override      protected void generateFooter(Writer writer) throws IOException {          writer.write(" \t}");          writer.write("\n\n");          writer.write("}");      }  }</code></pre>    <p> </p>    <p>来自：http://www.androidchina.net/6082.html</p>    <p> </p>