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);   } }