代碼片--Android--Handler&Message

public class MainActivity extends ActionBarActivity {

    Button b;
    ImageView i;
    String path="http://pic.nipic.com/2007-12-23/200712231523651_2.jpg";
    ProgressDialog d;
    Handler handler=new Handler(){

        @Override
        public void handleMessage(Message msg) {
            byte[] data=(byte[]) msg.obj;
            Bitmap bm=BitmapFactory.decodeByteArray(data, 0, data.length);
            i.setImageBitmap(bm);
            if(msg.what==1){
                d.dismiss();
            }
        }

    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        b=(Button) findViewById(R.id.button1);
        i=(ImageView) findViewById(R.id.imageView1);
        d=new ProgressDialog(this);
        d.setTitle("提示信息");
        d.setMessage("下載中，請稍後....");
        d.setCancelable(false);
        b.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                new Thread(new MyThread()).start();
                d.show();
            }
        });
    }
    class MyThread implements Runnable{

        @Override
        public void run() {
            // TODO Auto-generated method stub
            HttpClient httpClient=new DefaultHttpClient();
            HttpGet httpGet=new HttpGet(path);
            try {
                HttpResponse httpResponse =httpClient.execute(httpGet);
                if(httpResponse.getStatusLine().getStatusCode()==200){
                    byte[] data=EntityUtils.toByteArray(httpResponse.getEntity());
                    Message message=Message.obtain();
                    message.obj=data;
                    message.what=1;
                    handler.sendMessage(message);
                }
            } catch (ClientProtocolException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

    }
}