git clone https://android.googlesource.com/platform/frameworks/volley

mQueue = Volley.newRequestQueue(getApplicationContext());
mQueue.add(new JsonObjectRequest(Method.GET, url, null,
            new Listener() {
                @Override
                public void onResponse(JSONObject response) {
                    Log.d(TAG, "response : " + response.toString());
                }
            }, null));
mQueue.start();

// imageView是一个ImageView实例
// ImageLoader.getImageListener的第二个参数是默认的图片resource id
// 第三个参数是请求失败时候的资源id，可以指定为0
ImageListener listener = ImageLoader.getImageListener(imageView, android.R.drawable.ic_menu_rotate, android.R.drawable.ic_delete);
mImageLoader.get(url, listener);

mImageView.setImageUrl(url, imageLoader)

mImageLoader = new ImageLoader(mRequestQueue, new BitmapLruCache());
... ...
 
if(holder.imageRequest != null) {
    holder.imageRequest.cancel();
}
holder.imageRequest = mImageLoader.get(BASE_UR + item.image_url, holder.imageView, R.drawable.loading, R.drawable.error);

mImageLoader = new ImageLoader(mRequestQueue, new BitmapLruCache());

/**
 * Simple cache adapter interface. If provided to the ImageLoader, it
 * will be used as an L1 cache before dispatch to Volley. Implementations
 * must not block. Implementation with an LruCache is recommended.
 */
public interface ImageCache {
    public Bitmap getBitmap(String url);
    public void putBitmap(String url, Bitmap bitmap);
}

@Override
protected Response parseNetworkResponse(NetworkResponse response) {
    try {
        String json = new String(
                response.data, HttpHeaderParser.parseCharset(response.headers));
        return Response.success(
                gson.fromJson(json, clazz), HttpHeaderParser.parseCacheHeaders(response));
    } catch (UnsupportedEncodingException e) {
        return Response.error(new ParseError(e));
    } catch (JsonSyntaxException e) {
        return Response.error(new ParseError(e));
    }
}

mRequestQueue.add( new GsonRequest(url, ListResponse.class, null,
    new Listener() {
        public void onResponse(ListResponse response) {
            appendItemsToList(response.item);
            notifyDataSetChanged();
        }
    }
}

@Override public void onPostExecute(Result r) {
    if (getActivity() == null) {
        return;
    }
    // ...
}

@Override
public void onStop() {
    for (Request <?> req : mInFlightRequests) {
        req.cancel();
    }
    ...
}

@Override pubic void onStop() {
    mRequestQueue.cancelAll(this);
    ...
}

@Override public void onStop() {
    mRequestQueue.cancelAll( new RequestFilter() {})
    ...
    // or
    mRequestQueue.cancelAll(new Object());
    ...