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);
//                }
//            });
        }
    };