Android：回调机制

https://www.jianshu.com/p/3f86b7949f20 

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!";
	}

}

//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

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