Handler的理解

A Handler allows you to send and process Message and Runnable objects associated with a thread's MessageQueue. Each Handler instance is associated with a single thread and that thread's message queue. When you create a new Handler, it is bound to the thread / message queue of the thread that is creating it -- from that point on, it will deliver messages and runnables to that message queue and execute them as they come out of the message queue.

Handler使你能够send 和处理与一个线程的消息队列相关的Message和Runnable对象。每一个Handler实例是和一个指定线程及其消息队列相关联的。Handler对象会被绑定到创建它的thread及其消息队列。然后你就可以delivere Message and Runnable 对象，handler 会按照顺序依次处理这些他们。

下面是实现的小例子

package hust.ophone.RunnableTry;

import android.app.Activity;

import android.os.Bundle;

import android.os.Handler;

import android.os.Looper;

import android.os.Message;

import android.os.SystemClock;

import android.util.Log;

public class RunnableTry extends Activity {

/** Called when the activity is first created. */

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

sendMessage();

}

public void sendMessage() {

MHandler mHandler = new MHandler();

//Returns a new Message from the global message pool. More efficient than creating and allocating new //instances. The retrieved message has its handler set to this instance (Message.target == this).

Message msg = mHandler.obtainMessage();

Log.v("TAG", msg.toString());

msg.sendToTarget();

}

class MHandler extends Handler {

public MHandler() {

}

public MHandler(Looper l) {

super(l);

}

@Override

public void handleMessage(Message msg) {

int count = 0;

while (count++ < 10) {

Log.d("TAG", "处理消息");

}

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