/**

     * 根据网络url获取bitmap对象

     * @param url

     * @param width  要获取的宽度

     * @param height 要获取的高度 防止内存溢出

     * @return

     */

    public static Bitmap returnBitMap(String url, int width,int height) {

        Bitmap bitmap = null;

        try {

            HttpGet httpRequest = new HttpGet(url);

            Log.d("returnbitmap", "url="+url);

            HttpClient httpclient = new DefaultHttpClient();

            HttpResponse response = (HttpResponse) httpclient.execute(httpRequest);

            HttpEntity entity = response.getEntity();

            BufferedHttpEntity bufferedHttpEntity = new BufferedHttpEntity(entity);

            InputStream is = bufferedHttpEntity.getContent();

            BitmapFactory.Options options = new BitmapFactory.Options();

            options.inJustDecodeBounds = true; //只获取图片的高宽

            int scale = 1;

            BitmapFactory.decodeStream(is,null,options);

            int w = options.outWidth;

            int h = options.outHeight;

            Log.d("returnbitmap", "w="+w+";h="+h+";width="+width+";height="+height);

            while(true)

            {

                if ((width>0 && w < width) || (height>0 && h < height))

                {

                    break;

                }

                w /= 2;

                h /= 2;

                scale *= 2;

            }

            options.inJustDecodeBounds = false;

            options.inSampleSize = scale;

            is = bufferedHttpEntity.getContent();//重新获取流

            bitmap = BitmapFactory.decodeStream(is,null,options);

            Log.d("returnbitmap", "bitmap="+bitmap+(bitmap==null?"bitmap is null":"bitmap is not null"));

            is.close();

        } catch (IOException e) {

            e.printStackTrace();

        }

         catch (OutOfMemoryError e) {

             e.printStackTrace();

         }

        return bitmap;

    }