Android之Handler详解（2）

二：sendMessage版本的Handler的使用

这里介绍几种模型:

a、默认的Handler（消息处理队列挂在主线程上）

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package com.dxyh.test;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class MainActivity extends Activity				  implements OnClickListener {	private final static String TAG = "HandlerTest";		private final static int TASK_BEGIN	= 1;	private final static int TASK_1	= 2;	private final static int TASK_2	= 3;	private final static int TASK_END	= 4;		private Button btnStart = null;	private Button btnStop = null;	    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);                btnStart = (Button) findViewById(R.id.btn_start);        btnStart.setOnClickListener(this);        btnStop = (Button) findViewById(R.id.btn_stop);        btnStop.setOnClickListener(this);                Log.i(TAG, "[M_TID:" + Thread.currentThread().getId() + "]");    }        Handler mHandler = new Handler() {    	// 注意：在各个case后面不能做太耗时的操作，否则出现ANR对话框    	@Override    	public void handleMessage(Message msg) {    		switch (msg.what) {    		case TASK_BEGIN:    			Log.i(TAG, "[H_TID:" +    				Thread.currentThread().getId() + "] Get TASK_BEGIN");    			break;    			    		case TASK_1:    			Log.i(TAG, "[H_TID:" +    				Thread.currentThread().getId() + "] Get TASK_1");    			break;    			    		case TASK_2:    			Log.i(TAG, "[H_TID:" +    				Thread.currentThread().getId() + "] Get TASK_2");    			break;    			    		case TASK_END:    			Log.i(TAG, "[H_TID:" +    				Thread.currentThread().getId() + "] Get TASK_END");    			finish();    			break;    		}    		super.handleMessage(msg);    	}    };        public void onClick(View view) {    	switch (view.getId()) {    	case R.id.btn_start:    		// 启动任务（消息只有标识，立即投递）    		mHandler.sendEmptyMessage(TASK_BEGIN);    		Log.i(TAG, "Send TASK_BEGIN to handler.");    		    		// 开始任务1（在mHandler的消息队列中获取一个Message对象，避免重复构造）    		Message msg1 = mHandler.obtainMessage(TASK_1);    		msg1.obj = "This is task1";    		mHandler.sendMessage(msg1);    		Log.i(TAG, "Send TASK_1 to handler.");    		    		// 开启任务2（和上面类似）    		Message msg2 = Message.obtain();    		msg2.arg1 = 10;    		msg2.arg2 = 20;    		msg2.what = TASK_2;    		mHandler.sendMessage(msg2);    		Log.i(TAG, "Send TASK_2 to handler.");    		break;    		    	case R.id.btn_stop:    		// 结束任务（空消息体，延时2s投递）    		mHandler.sendEmptyMessageDelayed(TASK_END, 2000);    		Log.i(TAG, "Send TASK_END to handler.");    		break;    	}}}

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运行结果：

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b、消息队列仍绑定在主线程上，但在子线程中发送消息。

package com.dxyh.test;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.util.Log;public class MainActivity extends Activity {	private final static String TAG = "HandlerTest";		private final static int TASK_BEGIN	= 1;	private final static int TASK_1	= 2;	private final static int TASK_2	= 3;	private final static int TASK_END	= 4;	    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);                Log.i(TAG, "[M_TID:" + Thread.currentThread().getId() + "]" +        		"This is in main thread.");                workThread.start();    }        Handler mHandler = new Handler() {    	// 注意：在各个case后面不能做太耗时的操作，否则出现ANR对话框    	@Override    	public void handleMessage(Message msg) {    		switch (msg.what) {    		case TASK_BEGIN:    			Log.i(TAG, "[H_TID:" +				Thread.currentThread().getId() + "] Get TASK_BEGIN");    			break;    			    		case TASK_1:    			Log.i(TAG, "[H_TID:" +				Thread.currentThread().getId() + "] Get TASK_1");    			break;    			    		case TASK_2:    			Log.i(TAG, "[H_TID:" +				Thread.currentThread().getId() + "] Get TASK_2");    			break;    			    		case TASK_END:    			Log.i(TAG, "[H_TID:" +				Thread.currentThread().getId() + "] Get TASK_END");    			finish();    			break;    		}    		super.handleMessage(msg);    	}    };        Thread workThread = new Thread() {    	// 你可以在run方法内做任何耗时的操作，然后将结果以消息形式投递到主线程的消息队列中    	@Override    	public void run() {    		// 启动任务（消息只有标识，立即投递）    		mHandler.sendEmptyMessage(TASK_BEGIN);    		Log.i(TAG, "[S_TID:" + Thread.currentThread().getId() + "]" +    				"Send TASK_START to handler.");    		    		// 开始任务1（在mHandler的消息队列中获取一个Message对象，避免重复构造）    		Message msg1 = mHandler.obtainMessage(TASK_1);    		msg1.obj = "This is task1";    		mHandler.sendMessage(msg1);    		Log.i(TAG, "[S_TID:" + Thread.currentThread().getId() + "]" +    				"Send TASK_1 to handler.");    		    		// 开启任务2（和上面类似）    		Message msg2 = Message.obtain();    		msg2.arg1 = 10;    		msg2.arg2 = 20;    		msg2.what = TASK_2;    		mHandler.sendMessage(msg2);    		Log.i(TAG, "[S_TID:" + Thread.currentThread().getId() + "]" +    				"Send TASK_2 to handler.");    		    		// 结束任务（空消息体，延时2s投递）    		mHandler.sendEmptyMessageDelayed(TASK_END, 2000);    		Log.i(TAG, "[S_TID:" + Thread.currentThread().getId() + "]" +    				"Send TASK_END to handler.");    	}    };}

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运行结果：