listview加载显示图片

public class ImageAndTextListAdapter extends ArrayAdapter<ImageAndText> {

	    private ListView listView;
	    private AsyncImageLoader asyncImageLoader;

	    public ImageAndTextListAdapter(Activity activity, List<ImageAndText> imageAndTexts, ListView listView) {
	        super(activity, 0, imageAndTexts);
	        this.listView = listView;
	        asyncImageLoader = new AsyncImageLoader();
	    }

	    public View getView(int position, View convertView, ViewGroup parent) {
	        Activity activity = (Activity) getContext();

	        // Inflate the views from XML
	        View rowView = convertView;
	        ViewCache viewCache;
	        if (rowView == null) {
	            LayoutInflater inflater = activity.getLayoutInflater();
	            rowView = inflater.inflate(R.layout.image_and_text_row, null);
	            viewCache = new ViewCache(rowView);
	            rowView.setTag(viewCache);
	        } else {
	            viewCache = (ViewCache) rowView.getTag();
	        }
	        ImageAndText imageAndText = getItem(position);

	        // Load the image and set it on the ImageView
	        String imageUrl = imageAndText.getImageUrl();
	        ImageView imageView = viewCache.getImageView();
	        imageView.setTag(imageUrl);
	        Drawable cachedImage = asyncImageLoader.loadDrawable(imageUrl, new ImageCallback() {
	            public void imageLoaded(Drawable imageDrawable, String imageUrl) {
	                ImageView imageViewByTag = (ImageView) listView.findViewWithTag(imageUrl);
	                if (imageViewByTag != null) {
	                    imageViewByTag.setImageDrawable(imageDrawable);
	                }
	            }
	        });
			if (cachedImage == null) {
				imageView.setImageResource(R.drawable.default_image);
			}else{
				imageView.setImageDrawable(cachedImage);
			}
	        // Set the text on the TextView
	        TextView textView = viewCache.getTextView();
	        textView.setText(imageAndText.getText());

	        return rowView;
	    }

}-------------------------------------------------------------------------------------------------

public class AsyncImageLoader {

     private HashMap<String, SoftReference<Drawable>> imageCache;               public AsyncImageLoader() {             imageCache = new HashMap<String, SoftReference<Drawable>>();         }               public Drawable loadDrawable(final String imageUrl, final ImageCallback imageCallback) {             if (imageCache.containsKey(imageUrl)) {                 SoftReference<Drawable> softReference = imageCache.get(imageUrl);                 Drawable drawable = softReference.get();                 if (drawable != null) {                     return drawable;                 }             }             final Handler handler = new Handler() {                 public void handleMessage(Message message) {                     imageCallback.imageLoaded((Drawable) message.obj, imageUrl);                 }             };             new Thread() {                 @Override                 public void run() {                     Drawable drawable = loadImageFromUrl(imageUrl);                     imageCache.put(imageUrl, new SoftReference<Drawable>(drawable));                     Message message = handler.obtainMessage(0, drawable);                     handler.sendMessage(message);                 }             }.start();             return null;         }              public static Drawable loadImageFromUrl(String url) {            URL m;            InputStream i = null;            try {                m = new URL(url);                i = (InputStream) m.getContent();            } catch (MalformedURLException e1) {                e1.printStackTrace();            } catch (IOException e) {                e.printStackTrace();            }            Drawable d = Drawable.createFromStream(i, "src");            return d;        }               public interface ImageCallback {             public void imageLoaded(Drawable imageDrawable, String imageUrl);         }

}