android Handler浅谈

首先得明白　这是浅谈，　也就是说研究不深入，后续会继续跟踪．

我个人认为　android 线程间通信用　Handler +Message 方式．

进程间通信用AIDL.

呵呵，深知自己能力很差，　只是个人理解，希望明白的告诉我下．

为什么说　handler主要用于线呈间通信呢？

Java代码
package com.ray.handler;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.drawable.Drawable;
import android.view.View;

public class BounceView extends View {
float x = 40;

public BounceView(Context context) {
super(context);
}

@Override
protected void onDraw(Canvas canvas) {
x+=10;
Paint mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setColor(Color.GREEN);
canvas.drawCircle(x, 40, 40, mPaint);
}
}

上面的代码就是实现了一个简单的Widget .

package com.ray.handler;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.Window;

public class TestHandler extends Activity {
protected static final int GUIUpdateIDENTIFIER = 0x101;

Thread myRefreshThread = null;
BounceView myBounceView = null;

Handler myHandler = new Handler() {
public void handleMessage(Message msg) {
switch (msg.what) {
case TestHandler.GUIUpdateIDENTIFIER:
myBounceView.invalidate();
break;
}
super.handleMessage(msg);
}
};
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);

this.myBounceView = new BounceView(this);
this.setContentView(this.myBounceView);
new Thread(new myThread()).start();
}

class myThread implements Runnable {
public void run() {
while (!Thread.currentThread().isInterrupted()) {

[color=White][color=White][color=Red] Message message = new Message();
message.what = TestHandler.GUIUpdateIDENTIFIER;

TestHandler.this.myHandler.sendMessage(message); [/color][/color][/color]
try {
Thread.sleep(100);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
}
}

红色这几句很诡异，就是用来给Ui主线程发消息．　　ＵＩ主线程据说有消息队列，呵呵．Handler在哪个现成创建的．默认就和哪个线程的Looper　绑定．　就可以往哪个线程的消息队列丢消息．

我现在还不太明白的是．　　Handler丢了消息，　　在绑定的线程中　为什么Handler又能处理消息呢？

Handler Looper关系还要进一步研究．

主要是为了定时，或中断，或通知更新ＵＩ．　又不使ＵＩ反应停止或太慢，用多线程发消息办法很不错．

呵呵，多少有点收获吧，回帖子吧？

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