Androidの多线程之Handler创建新线程

两个Handler，一个是主线程的mainHandler，一个是获取HandlerThread的looper的Handler.

mainHandler在新线程发出消息，在主线程处理接受的消息。

looperHandler拥有looper后即可post(Runnable)，发起新线程，然后通过mainHandler在新线程里发送消息到主线程的handler。

这里创建两个handler，一个是mainHandler维护主线程的looper,一个是looperHandler拥护HandlerThread的looper。

1.mainHandler处理消息，复写handlerMessage()方法处理消息。

2.looperHandler应通过HandlerThread获取looper来构造，而且HandlerThread必须开启，否则得不到looper。

3.looperHandler来post一个runnable对象，在runnable里复写run()方法，在里面用mainHandler发送方消息。

package com.bvin.handler;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.LinearLayout.LayoutParams;
import android.widget.TextView;

public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    
    private Handler loopHandler ;
    private Handler mainHandler; 
    private TextView tv;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        initViews();
        HandlerThread ht = new HandlerThread("handler thread");
        ht.start();//loopHandler的runnable这里先开始le，而mainHandler是点击之后
        loopHandler = new Handler(ht.getLooper());
        mainHandler= new Handler(){

            @Override
            public void handleMessage(Message msg) {
                // TODO Auto-generated method stub
                super.handleMessage(msg);
                if(msg.what==2012){
                    
                    tv.setText(msg.getData().getString("s"));
                }
                
            }
        };
    }
    
    
    private void initViews(){
        
        LinearLayout layout = new LinearLayout(this);
        layout.setOrientation(LinearLayout.VERTICAL);
        LayoutParams params = new LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.WRAP_CONTENT);
        tv = new TextView(this);
        tv.setText("本来");
        Button bt = new Button(this);
        
        bt.setText("开动");
        bt.setOnClickListener(new View.OnClickListener() {
            
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                mainHandler.post(new Runnable(){

                    @Override
                    public void run() {
                        // TODO Auto-generated method stub
                        Log.e("mainHandler所在当前线程", ""+Thread.currentThread().getName());
                        //tv.setText("对不对");
                    }
                });
                 
                loopHandler.post(new Runnable(){

                    @Override
                    public void run() {
                        // TODO Auto-generated method stub
                        Log.e("loopHandler所在当前线程", ""+Thread.currentThread().getName());
                        Message msg = mainHandler.obtainMessage();
                        msg.what = 2012;
                        Bundle bundle = new Bundle();
                        bundle.putString("s", "从"+Thread.currentThread().getName()+"线程传过来的");
                        msg.setData(bundle);
                        msg.sendToTarget();
                    }
                });
                
            }
        });
        layout.addView(bt,params);
        layout.addView(tv,params);
        setContentView(layout);
        
    }
}