Android之Handler详解（2）

Android之Handler详解（二）

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）

 

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;
    	}
}
}

 

运行结果：

 

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.");
    	}
    };
}

 

运行结果：