Android：回调机制

 

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public class Fruits {       public interface Apple {         public String info();     }   }   //匿名内部类 public class Test {       public static void main(String[] args) {         // TODO Auto-generated method stub           Fruits.Apple apple = new Fruits.Apple() {               @Override             public String info() {                 // TODO Auto-generated method stub                 return "I am an Apple";             }         };         System.out.println(apple.info());// I am an Apple     }   }   //继承接口 public class SonFruits implements Fruits.Apple {       public static void main(String[] args) {         // TODO Auto-generated method stub         SonFruits sonFruits = new SonFruits();         sonFruits.info();         System.out.println("sonFruits.info()->" + sonFruits.info());     }       @Override     public String info() {         // TODO Auto-generated method stub         return "I am an  Apple!";     }   }

 

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//回调方法的接口 public interface CallBack {     public void callBackMethod(); }   //回调方法的实现类 public class CallBackListener implements CallBack {       @Override     public void callBackMethod() {         // TODO Auto-generated method stub         System.out.println("回调");     }   }   //调用类 public class Caller {       private CallBackListener callBackListener;       public void call() {         this.callBackListener.callBackMethod();     }       public void setCalBack(CallBackListener callBackListener2) {         this.callBackListener = callBackListener;     }   }     //业务处理类 public class Main {       public static void main(String[] args) {         // TODO Auto-generated method stub         Caller caller = new Caller();         caller.setCalBack(new CallBackListener());         caller.call();     }   }

Button点击事件
CallBack------->OnClickListener接口
CallBackListener--------->实现OnClickListener接口的类
Caller-------->Button对象
Main-------->业务处理类（Activity）

举个栗子

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frameworks/base/core/java/android/view/GestureDetector.java public class GestureDetector {       1.     public interface OnGestureListener {//内部 手势接口         2.         public static class SimpleOnGestureListener implements OnGestureListener, OnDoubleTapListener {//实现接口的类           will@s2:~/ZK-Rxxx_Android7.1/ZK_RXXX_RK3288_ANDROID7.1$ grep -rn "SimpleOnGestureListener" ./frameworks/base/services/ ./frameworks/base/services/core/java/com/android/server/policy/SystemGesturesPointerEventListener.java:267:    private final class FlingGestureDetector extends GestureDetector.SimpleOnGestureListener { ./frameworks/base/services/core/java/com/android/server/display/OverlayDisplayWindow.java:363:            new GestureDetector.SimpleOnGestureListener() { ./frameworks/base/services/core/java/com/android/server/wm/TaskTapPointerEventListener.java:181:    private final class TwoFingerScrollListener extends GestureDetector.SimpleOnGestureListener { ./frameworks/base/services/accessibility/java/com/android/server/accessibility/AccessibilityGestureDetector.java:43:class AccessibilityGestureDetector extends GestureDetector.SimpleOnGestureListener { ./frameworks/base/services/accessibility/java/com/android/server/accessibility/MagnificationGestureHandler.java:26:import android.view.GestureDetector.SimpleOnGestureListener; ./frameworks/base/services/accessibility/java/com/android/server/accessibility/MagnificationGestureHandler.java:332:    private final class MagnifiedContentInteractionStateHandler extends SimpleOnGestureListener will@s2:~/ZK-Rxxx_Android7.1/ZK_RXXX_RK3288_ANDROID7.1$           3. /frameworks/base/services/core/java/com/android/server/policy/SystemGesturesPointerEventListener.java private final class FlingGestureDetector extends GestureDetector.SimpleOnGestureListener { 4.          frameworks/base/services/core/java/com/android/server/policy/PhoneWindowManager.java                                // monitor for system gestures         mSystemGestures = new SystemGesturesPointerEventListener(context,                 new SystemGesturesPointerEventListener.Callbacks() { //业务处理