做一个简单的关于Handler，Looper，Message的小演示，代码主界面一个Button按钮，点击发送消息（累计）给线程的Looper循环，然后在LogCat中打印出来：

package zhangphil.looper;import android.os.Bundle;import android.os.Handler;import android.os.Looper;import android.os.Message;import android.util.Log;import android.view.View;import android.widget.Button;import android.app.Activity;public class MainActivity extends Activity {	private Handler mHandler;	private final int MESSAGE_WHAT = 101;	@Override	protected void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		setContentView(R.layout.activity_main);		final Button button = (Button) findViewById(R.id.button);		button.setOnClickListener(new View.OnClickListener() {			private int count = 0;			@Override			public void onClick(View v) {				mHandler.obtainMessage(MESSAGE_WHAT, count).sendToTarget();				button.setText("发送了 " + count);				count++;			}		});		new MessageReceiveThread().start();	}	private class MessageReceiveThread extends Thread {		@Override		public void run() {			Looper.prepare();			mHandler = new Handler() {				@Override				public void handleMessage(Message msg) {					switch (msg.what) {					case MESSAGE_WHAT:						String text = msg.obj + "";						Log.d("收到-->", text);						break;					}				}			};			Looper.loop();		}	}}

MainActivity.java需要的activity_main.xml文件：