android给子线程传值

转载http://www.cnblogs.com/jackhuclan/archive/2013/07/10/3182084.html



从主线程发送消息到子线程（准确地说应该是非UI线程）

package com.zhuozhuo;

import android.app.Activity;

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.view.View.OnClickListener;



public class LooperThreadActivity extends Activity{

/** Called when the activity is first created. */



private final int MSG_HELLO = 0;

private Handler mHandler;



@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

new CustomThread().start();//新建并启动CustomThread实例



findViewById(R.id.send_btn).setOnClickListener(new OnClickListener() {



@Override

public void onClick(View v) {//点击界面时发送消息

String str = "hello";

Log.d("Test", "MainThread is ready to send msg:" + str);

mHandler.obtainMessage(MSG_HELLO, str).sendToTarget();//发送消息到CustomThread实例



}

});



}











class CustomThread extends Thread {

@Override

public void run() {

//建立消息循环的步骤

Looper.prepare();//1、初始化Looper

mHandler = new Handler(){//2、绑定handler到CustomThread实例的Looper对象

public void handleMessage (Message msg) {//3、定义处理消息的方法

switch(msg.what) {

case MSG_HELLO:

Log.d("Test", "CustomThread receive msg:" + (String) msg.obj);

}

}

};

Looper.loop();//4、启动消息循环

}

}

}







从非UI线程传递消息到UI线程(界面主线程），因为主界面已经有MessageQueue，所以可以直接获取消息处理消息。而上面由主线程向非UI线程中处理消息的时候，非UI线程需要先添加消息队列，然后处理消息循环。



public class ThreadHandlerActivity extends Activity {

/** Called when the activity is first created. */



private static final int MSG_SUCCESS = 0;//获取图片成功的标识

private static final int MSG_FAILURE = 1;//获取图片失败的标识



private ImageView mImageView;

private Button mButton;



private Thread mThread;



private Handler mHandler = new Handler() {

public void handleMessage (Message msg) {//此方法在ui线程运行

switch(msg.what) {

case MSG_SUCCESS:

mImageView.setImageBitmap((Bitmap) msg.obj);//imageview显示从网络获取到的logo

Toast.makeText(getApplication(), getApplication().getString(R.string.get_pic_success), Toast.LENGTH_LONG).show();

break;

case MSG_FAILURE:

Toast.makeText(getApplication(), getApplication().getString(R.string.get_pic_failure), Toast.LENGTH_LONG).show();

break;

}

}

};



@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

mImageView= (ImageView) findViewById(R.id.imageView);//显示图片的ImageView

mButton = (Button) findViewById(R.id.button);

mButton.setOnClickListener(new OnClickListener() {



@Override

public void onClick(View v) {

if(mThread == null) {

mThread = new Thread(runnable);

mThread.start();//线程启动

}

else {

Toast.makeText(getApplication(), getApplication().getString(R.string.thread_started), Toast.LENGTH_LONG).show();

}

}

});

}



Runnable runnable = new Runnable() {



@Override

public void run() {//run()在新的线程中运行

HttpClient hc = new DefaultHttpClient();

HttpGet hg = new HttpGet("http://csdnimg.cn/www/images/csdnindex_logo.gif");//获取csdn的logo

final Bitmap bm;

try {

HttpResponse hr = hc.execute(hg);

bm = BitmapFactory.decodeStream(hr.getEntity().getContent());

} catch (Exception e) {

mHandler.obtainMessage(MSG_FAILURE).sendToTarget();//获取图片失败

return;

}

mHandler.obtainMessage(MSG_SUCCESS,bm).sendToTarget();//获取图片成功，向ui线程发送MSG_SUCCESS标识和bitmap对象

// mImageView.setImageBitmap(bm); //出错！不能在非ui线程操作ui元素

// mImageView.post(new Runnable() {//另外一种更简洁的发送消息给ui线程的方法。

//

// @Override

// public void run() {//run()方法会在ui线程执行

// mImageView.setImageBitmap(bm);

// }

// });

}

};