android利用消息机制获取网络图片

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
  xmlns:tools="http://schemas.android.com/tools" 
  android:layout_width="match_parent" 
  android:layout_height="match_parent" 
  tools:context="cn.edu.huse.handle.MainActivity" > 
 
  <ImageView 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:id="@+id/iv_image" /> 
  <Button  
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:onClick="getImage" 
    android:text="获取网络图片" 
    android:layout_gravity="bottom|center" 
    android:layout_marginBottom="20dp"/> 
 
</FrameLayout> 

package cn.edu.huse.handle; 
 
import java.io.InputStream; 
import java.net.HttpURLConnection; 
import java.net.MalformedURLException; 
import java.net.URL; 
 
import android.app.Activity; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.os.Bundle; 
import android.os.Handler; 
import android.os.Message; 
import android.view.View; 
import android.widget.ImageView; 
import android.widget.Toast; 
 
/** 
 * @author Lenovo 
 * 
 */ 
public class MainActivity extends Activity { 
 
  protected static final int LOAD_SUCCESS = 0; 
 
  private static final int LOAD_ERROR = 1; 
 
  private ImageView iv_image; 
   
  private Handler mHandler = new Handler(){ 
    public void handleMessage(Message msg) { 
      switch (msg.what) { 
      case LOAD_SUCCESS:   //加载图片成功 
        Bitmap bitmap = (Bitmap) msg.obj; //获取消息里面的数据 
        iv_image.setImageBitmap(bitmap); 
        break; 
      case LOAD_ERROR:  //加载失败 
        Toast.makeText(MainActivity.this, "图片加载失败", 0).show(); 
        break; 
      } 
    }; 
  }; 
 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
     
    iv_image = (ImageView) findViewById(R.id.iv_image); 
  } 
   
  public void getImage(View v){ 
    new Thread(new Runnable() { 
       
      @Override 
      public void run() { 
        String path = "http://p2.so.qhimgs1.com/bdr/_240_/t01666725c7200ad5ae.jpg"; 
         
        try { 
          //1、获取URL 
          URL url = new URL(path); 
          //2、得到连接对象 
          HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 
          //设置连接时长 
          conn.setConnectTimeout(5000); 
          //设置请求方式 
          conn.setRequestMethod("GET"); 
          //判断是否响应成功 
          if(conn.getResponseCode() == 200){ 
            //3、获取输入流 
            InputStream inputStream = conn.getInputStream(); 
            //4、获得图片资源Bitmap 
            Bitmap bitmap = BitmapFactory.decodeStream(inputStream); 
            //消息对象 
            Message msg = new Message(); 
            msg.what = LOAD_SUCCESS; //唯一标识 
            msg.obj = bitmap;   //消失里面写在的数据 
            mHandler.sendMessage(msg); //发送消失给Handle 
          }else{ 
            alertUses(); 
          } 
           
        } catch (Exception e) { 
          e.printStackTrace(); 
          alertUses(); 
        } 
      } 
    }).start(); 
  } 
   
  /** 
   * 土司提醒用户，图片加载失败 
   */ 
  public void alertUses(){ 
    mHandler.sendEmptyMessage(LOAD_ERROR); 
  } 
}