Handler的理解
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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。
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下面是实现的小例子
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package hust.ophone.RunnableTry;
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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;
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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();
?? ? }?
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?? ? 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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