Android(安卓)从缓存中读取图片并异步加载的类[转]

public class AsyncImageLoader {    //SoftReference是软引用，是为了更好的为了系统回收变量    private HashMap<String, SoftReference<Drawable>> imageCache;    public AsyncImageLoader() {        imageCache = new HashMap<String, SoftReference<Drawable>>();    }        public Drawable loadDrawable(final String imageUrl,final ImageView imageView, final ImageCallback imageCallback){        if (imageCache.containsKey(imageUrl)) {            //从缓存中获取            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, imageView,imageUrl);            }        };        //建立新一个新的线程下载图片        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;    }        //回调接口    public interface ImageCallback {        public void imageLoaded(Drawable imageDrawable,ImageView imageView, String imageUrl);    }}public class WeiBoAdapater extends BaseAdapter{        private AsyncImageLoader asyncImageLoader;        @Override        public int getCount() {            // TODO Auto-generated method stub            return wbList.size();        }        @Override        public Object getItem(int position) {            // TODO Auto-generated method stub            return wbList.get(position);        }        @Override        public long getItemId(int position) {            // TODO Auto-generated method stub            return position;        }        @Override        public View getView(int position, View convertView, ViewGroup parent) {            // TODO Auto-generated method stub            convertView = LayoutInflater.from(getApplicationContext()).inflate(R.layout.weibo, null);            WeiBoHolder wh = new WeiBoHolder();            wh.wbicon = (ImageView) convertView.findViewById(R.id.wbicon);            wh.wbtext = (TextView) convertView.findViewById(R.id.wbtext);            wh.wbtime = (TextView) convertView.findViewById(R.id.wbtime);            wh.wbuser = (TextView) convertView.findViewById(R.id.wbuser);            wh.wbimage=(ImageView) convertView.findViewById(R.id.wbimage);            WeiBoInfo wb = wbList.get(position);            if(wb != null)            {                convertView.setTag(wb.getId());                wh.wbuser.setText(wb.getUserName());                wh.wbtime.setText(wb.getTime());                wh.wbtext.setText(wb.getText(), TextView.BufferType.SPANNABLE);                                Drawable cachedImage = asyncImageLoader.loadDrawable(wb.getUserIcon(), wh.wbicon, new ImageCallback(){                   public void imageLoaded(Drawable imageDrawable,ImageView imageView,String imageUrl){                       imageView.setImageDrawable(imageDrawable);                   }                });                if (cachedImage == null)                {                    wh.wbicon.setImageResource(R.drawable.usericon);                }else{                    wh.wbicon.setImageDrawable(cachedImage);                }                                }                                  return convertView;        }            }
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