android 异步加载网络图片 例子 附完整源码

【实例截图】

【核心代码】

package com.javatechig.droid;
 
import java.io.InputStream;
 
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
 
public class ImageDownladerActivity extends Activity {
 
    private ImageView downloadedImg;
    private ProgressDialog simpleWaitDialog;
    private String downloadUrl = "http://www.9ori.com/store/media/images/8ab579a656.jpg";
 
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.asynch);
        Button imageDownloaderBtn = (Button) findViewById(R.id.downloadButton);
 
        downloadedImg = (ImageView) findViewById(R.id.imageView);
 
        imageDownloaderBtn.setOnClickListener(new OnClickListener() {
 
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                new ImageDownloader().execute(downloadUrl);
            }
 
        });
    }
 
    private class ImageDownloader extends AsyncTask {
 
        @Override
        protected Bitmap doInBackground(String... param) {
            // TODO Auto-generated method stub
            return downloadBitmap(param[0]);
        }
 
        @Override
        protected void onPreExecute() {
            Log.i("Async-Example", "onPreExecute Called");
            simpleWaitDialog = ProgressDialog.show(ImageDownladerActivity.this,
                    "Wait", "Downloading Image");
 
        }
 
        @Override
        protected void onPostExecute(Bitmap result) {
            Log.i("Async-Example", "onPostExecute Called");
            downloadedImg.setImageBitmap(result);
            simpleWaitDialog.dismiss();
 
        }
 
        private Bitmap downloadBitmap(String url) {
            // initilize the default HTTP client object
            final DefaultHttpClient client = new DefaultHttpClient();
 
            //forming a HttoGet request 
            final HttpGet getRequest = new HttpGet(url);
            try {
 
                HttpResponse response = client.execute(getRequest);
 
                //check 200 OK for success
                final int statusCode = response.getStatusLine().getStatusCode();
 
                if (statusCode != HttpStatus.SC_OK) {
                    Log.w("ImageDownloader", "Error "   statusCode   
                            " while retrieving bitmap from "   url);
                    return null;
 
                }
 
                final HttpEntity entity = response.getEntity();
                if (entity != null) {
                    InputStream inputStream = null;
                    try {
                        // getting contents from the stream 
                        inputStream = entity.getContent();
 
                        // decoding stream data back into image Bitmap that android understands
                        final Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
 
                        return bitmap;
                    } finally {
                        if (inputStream != null) {
                            inputStream.close();
                        }
                        entity.consumeContent();
                    }
                }
            } catch (Exception e) {
                // You Could provide a more explicit error message for IOException
                getRequest.abort();
                Log.e("ImageDownloader", "Something went wrong while"  
                        " retrieving bitmap from "   url   e.toString());
            } 
 
            return null;
        }
    }
}