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！