详解Android中自定义View的invalidate,Handler和postInvalidate

package com.yarin.android.Examples_05_01;

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

public class Activity01 extends Activity
{
private static final intREFRESH= 0x000001;

/* 声明GameView类对象 */
private GameViewmGameView= null;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);

/* 实例化GameView对象 */
this.mGameView = new GameView(this);

// 设置显示为我们自定义的View(GameView)
setContentView(mGameView);

// 开启线程
new Thread(new GameThread()).start();
}

//HandlermyHandler= new Handler()
//{
////接收到消息后处理
//public void handleMessage(Message msg)
//{switch (msg.what)
//{
//case Activity01.REFRESH:
//mGameView.invalidate();
//break;}
//super.handleMessage(msg);
//}
//};
//
//class GameThread implements Runnable
//{public void run()
//{while (!Thread.currentThread().isInterrupted())
//{Message message = new Message();
//message.what = Activity01.REFRESH;
////发送消息
//Activity01.this.myHandler.sendMessage(message);
//try
//{Thread.sleep(100);
//}
//catch (InterruptedException e)
//{Thread.currentThread().interrupt();
//}
//}
//}
//}
//**
// * 当然可以将GameThread类这样写
// * 同样可以更新界面，并且不在需要
// * Handler在接受消息
class GameThread implements Runnable
{
public void run()
{
while (!Thread.currentThread().isInterrupted())
{
try
{
Thread.sleep(100);
}
catch (InterruptedException e)
{
Thread.currentThread().interrupt();
}
//使用postInvalidate可以直接在线程中更新界面
mGameView.postInvalidate();
//如果用invalidate()则会出错
//mGameView.invalidate();
//FATAL EXCEPTION: Thread-8
// android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
// at android.view.ViewRoot.checkThread(ViewRoot.java:2802)
// at android.view.ViewRoot.invalidateChild(ViewRoot.java:607)
// at android.view.ViewRoot.invalidateChildInParent(ViewRoot.java:633)
// at android.view.ViewGroup.invalidateChild(ViewGroup.java:2505)
// at android.view.View.invalidate(View.java:5139)
// at com.yarin.android.Examples_05_01.Activity01$GameThread.run(Activity01.java:81)
// at java.lang.Thread.run(Thread.java:1096)
// 查看View源文件
//public void postInvalidate(int left, int top, int right, int bottom) {
// postInvalidateDelayed(0, left, top, right, bottom);
// }
//
// public void postInvalidateDelayed(long delayMilliseconds) {
// // We try only with the AttachInfo because there's no point in invalidating
// // if we are not attached to our window
// if (mAttachInfo != null) {
// Message msg = Message.obtain();
// msg.what = AttachInfo.INVALIDATE_MSG;
// msg.obj = this;
// mAttachInfo.mHandler.sendMessageDelayed(msg, delayMilliseconds);
// }

}
}
}


//详细事件处理见第三章
//当然这些事件也可以写在GameView中
//触笔事件
public boolean onTouchEvent(MotionEvent event)
{
return true;
}

//按键按下事件
public boolean onKeyDown(int keyCode, KeyEvent event)
{
return true;
}

//按键弹起事件
public boolean onKeyUp(int keyCode, KeyEvent event)
{
switch (keyCode)
{
//上方向键
case KeyEvent.KEYCODE_DPAD_UP:
mGameView.y-=3;
break;
//下方向键
case KeyEvent.KEYCODE_DPAD_DOWN:
mGameView.y+=3;
break;
}
return false;
}

public boolean onKeyMultiple(int keyCode, int repeatCount, KeyEvent event)
{
return true;
}
}