关于键盘触发事件和屏幕触发事件的问题

当在自定义View或者做游戏的时候，我们常常会用到键盘触发事件和屏幕触发事件！在自定义的View里的键盘触发事件（比如：onKeyDown(int keyCode, KeyEvent event)）和屏幕触发事件（onTouchEvent(MotionEvent event)）和activity里的键盘触发事件（比如：onKeyDown(int keyCode, KeyEvent event)）和屏幕触发事件（onTouchEvent(MotionEvent event)）是怎么样交互的呢？是怎样的一个运行原理呢？下面来看看：

1、屏幕触发事件：哪个activity或者视图，控件在最上层就最先触发这个控件里的屏幕触发事件，返回值如果是默认或者false就会一层一层的往下传递！如果返回值是true,则在执行完动作之后不会往下传递！

2、键盘触发事件：这个原理和屏幕触发事件差不多，但是不同的时，在没有设置控件处于焦点时，一般按键盘里的按键触发的是activity里的键盘触发事件（比如：onKeyDown(int keyCode, KeyEvent event)）。

下面来举个例子：

比如在做游戏的时候，我们经常自定义视图，我们一般都喜欢和使用触发本视图（GameView）里的键盘触发事件和屏幕触发事件，但是比如：onKeyDown(int keyCode, KeyEvent event）)，一般我们按键盘的时候直接触发的是activity里的键盘触发事件，怎样让它直接触发（GameView）里的键盘触发事件呢?

第一种方法：

例子1：

package net.loonggg.project;

import android.app.Activity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.MotionEvent;

public class MainActivity extends Activity {
    private GameView gameView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        gameView = new GameView(this);
        setContentView(gameView);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        System.out.println("MainActivity:" + " keyCode:" + keyCode + " evnet:"
                + event);
        return super.onKeyDown(keyCode, event);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        System.out.println("MainActivity:" + "  event:" + event + " x:"
                + event.getX() + " y:" + event.getY());
        return super.onTouchEvent(event);
    }
}




package net.loonggg.project;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;

public class GameView extends View {
    private Paint paint;
    private int pointX;
    private int pointY;

    public GameView(Context context) {
        super(context);
        // 设置GameView获得焦点
        this.setFocusable(true);
        paint = new Paint();
        paint.setColor(Color.YELLOW);
        Thread t = new Thread(new MyThread());
        t.start();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawCircle(pointX, pointY, 15, paint);
    }

    class MyThread implements Runnable {

        @Override
        public void run() {
            while (true) {
                try {
                    Thread.sleep(3000);
                    pointY = pointY + 10;
                    pointX = pointX + 10;
                    if (pointX > 200) {
                        break;
                    }
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                GameView.this.postInvalidate();
            }
        }

    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        System.out.println("GameView:" + " keyCode:" + keyCode + " evnet:"
                + event);
        //此事件不会传播出去
        return true;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        System.out.println("GameView:" + "  event:" + event + " x:"
                + event.getX() + " y:" + event.getY());
        //此事件不会传播出去
        return true;
    }

}

第二种方法：

package net.loonggg.project;

import android.app.Activity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.MotionEvent;

public class MainActivity extends Activity {
    private GameView gameView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        gameView = new GameView(this);
        setContentView(gameView);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        System.out.println("MainActivity:" + " keyCode:" + keyCode + " evnet:"
                + event);
        //把事件传递给gameView
        gameView.onKeyDown(keyCode, event);
        return super.onKeyDown(keyCode, event);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        System.out.println("MainActivity:" + "  event:" + event + " x:"
                + event.getX() + " y:" + event.getY());
        //把事件传递给gameView
        gameView.onTouchEvent(event);
        return super.onTouchEvent(event);
    }
}



package net.loonggg.project;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;

public class GameView extends View {
    private Paint paint;
    private int pointX;
    private int pointY;

    public GameView(Context context) {
        super(context);
        paint = new Paint();
        paint.setColor(Color.YELLOW);
        Thread t = new Thread(new MyThread());
        t.start();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawCircle(pointX, pointY, 15, paint);
    }

    class MyThread implements Runnable {

        @Override
        public void run() {
            while (true) {
                try {
                    Thread.sleep(3000);
                    pointY = pointY + 10;
                    pointX = pointX + 10;
                    if (pointX > 200) {
                        break;
                    }
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                GameView.this.postInvalidate();
            }
        }

    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        System.out.println("GameView:" + " keyCode:" + keyCode + " evnet:"
                + event);
        return super.onKeyDown(keyCode, event);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        System.out.println("GameView:" + "  event:" + event + " x:"
                + event.getX() + " y:" + event.getY());
        return super.onTouchEvent(event);
    }

}

在这里，推荐使用第二种方法，因为第一种方法有的模拟器不能够使用！