【AsynTask】Android异步加载一张图品

package com.test.asyntask;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.drawable.Drawable;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.ImageView;

import com.test.R;

public class AsynTask extends Activity {

    private ImageView mImage;
    private ProgressDialog mDialog;

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

        mDialog = new ProgressDialog(this);
        mDialog.setTitle("请稍等");
        mDialog.setMessage("正在加载...");

        mImage = (ImageView) findViewById(R.id.img);
        new ImageAsynTask().execute();
    }

    private class ImageAsynTask extends AsyncTask<Void, Void, Drawable> {
        @Override
        protected Drawable doInBackground(Void... params) {
            String url = "http://img1.3lian.com/img2011/07/20/05.jpg";
            return loadImages(url);
        }
        @Override
        protected void onPostExecute(Drawable result) {
            super.onPostExecute(result);
            mDialog.dismiss();
            mImage.setImageDrawable(result);
        }
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            mDialog.show();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        mDialog.dismiss();
    }

    public Drawable loadImages(String url) {
        try {
            return Drawable.createFromStream(
                    (InputStream) (new URL(url)).openStream(), "test");
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
}