android URL讀取網絡資源

Thread類中run()和start()方法的區別如下：
run()方法:在本線程內調用該Runnable對象的run()方法，可以重復多次調用；
start()方法:啟動一個線程，調用該Runnable對象的run()方法，不能多次啟動一個線程；

public class MainActivity extends Activity {

private ImageView iv ;
private Bitmap mbitmap;
Handler mhandle = new Handler(){
@Override
public void handleMessage(Message msg) {
if(msg.what==0x123){
iv.setImageBitmap(mbitmap);
}
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
iv = (ImageView) findViewById(R.id.imageView1);
new Thread(){
@Override
public void run() {
try {
URL url = new URL("http://a2.att.hudong.com/04/58/300001054794129041580438110.jpg");
InputStream is = url.openStream();
mbitmap = BitmapFactory.decodeStream(is);
mhandle.sendEmptyMessage(0x123);
is.close();
//再次打開，下載到本地
is = url.openStream();
OutputStream os = openFileOutput("cray.png", MODE_WORLD_READABLE);
byte [] buff = new byte[1024];
int hasread =0;
while((hasread=is.read(buff))>0){
os.write(buff, 0, hasread);
}
os.close();
is.close();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}.start();



}

}