HandlerThread 继承自Thread,内部封装了Looper。

首先Handler和HandlerThread的主要区别是：Handler与Activity在同一个线程中，HandlerThread与Activity不在同一个线程，而是别外新的线程中(Handler中不能做耗时的操作)。

用法：

import android.app.Activity;  import android.os.Bundle;  import android.os.Handler;  import android.os.Handler.Callback;  import android.os.HandlerThread;  import android.os.Message;      public class MainActivity extends Activity {      HandlerThread handlerThread = new HandlerThread("test");      Handler handler;            @Override      protected void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.activity_main);          System.out.println("cur_id="+Thread.currentThread().getId());                    handlerThread.start();          System.out.println("handlerThread.id=" + handlerThread.getId());          //post(runnable)，只是直接运行了run()，run()内ThreadId与UIThread是一样的  //      handler = new Handler();           //post(runnable)，将runnable运行在handlerThread中，这是非UIThread的          handler = new Handler(handlerThread.getLooper(), new Callback() {                            @Override              public boolean handleMessage(Message msg) {                  System.out.println("receive message.whatA=" + msg.what);                  if (msg.what == 1) {                      return true;//不再向外层传递                  } else {                      return false; //外层的handleMessage() 继续执行                  }                                }          }) {              @Override              public void handleMessage(Message msg) {                  // TODO Auto-generated method stub                  super.handleMessage(msg);                  System.out.println("receive message.whatB=" + msg.what);              }          };          handler.post(new Runnable() {                            @Override              public void run() {                  System.out.println("handler_post_cur_id="+Thread.currentThread().getId());                  handler.sendEmptyMessage(1);                  handler.sendEmptyMessage(2);              }          });                }    }

运行结果：

01-23 07:12:31.590: I/System.out(12386): cur_id=1  01-23 07:12:31.590: I/System.out(12386): handlerThread.id=1866  01-23 07:12:31.590: I/System.out(12386): handler_post_cur_id=1866  01-23 07:12:31.600: I/System.out(12386): receive message.whatA=1  01-23 07:12:31.600: I/System.out(12386): receive message.whatA=2  01-23 07:12:31.600: I/System.out(12386): receive message.whatB=2