2中方法：

1.

public byte[] downloadResource(Context context, String url)

			throws ClientProtocolException, IOException {

		isStop = false;

		ByteArrayBuffer buffer = null;

		HttpGet hp = new HttpGet(url);

		httpClient = new DefaultHttpClient();

		String netType = isNetType(context);

		if (netType != null & netType.equals("cmwap")) {

			HttpHost proxy = new HttpHost("10.0.0.172", 80);

			httpClient.getParams().setParameter(ConnRouteParams.DEFAULT_PROXY,

					proxy);

		}

		HttpConnectionParams.setConnectionTimeout(httpClient.getParams(),

				5 * 1000);

		HttpConnectionParams.setSoTimeout(httpClient.getParams(), 60 * 1000);

		HttpResponse response = httpClient.execute(hp);

		if (response.getStatusLine().getStatusCode() == 200) {

			inputstream = response.getEntity().getContent();

			if (inputstream != null) {

				int i = (int) response.getEntity().getContentLength();

				buffer = new ByteArrayBuffer(1024);

				byte[] tmp = new byte[1024];

				int len;

				while (((len = inputstream.read(tmp)) != -1)

						&& (false == isStop)) {

					buffer.append(tmp, 0, len);

				}

			}

			cancel();

		}

		return buffer.toByteArray();

	}

调用方法：

protected Bitmap doInBackground(WonderfulprogramInfo... params)

		{

			Bitmap bitmap = null;

			try

			{

				String urls = Constant.url + params[0].getWonderfulImgUrl();

				boolean isExists = Files.compare(urls);

				if (isExists == false)

				{	//网络下载图片数据

					Net net = new Net();

					byte[] data = net.downloadResource(HomeActivity.this, urls);

					bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);

					imagesCache.put(urls, bitmap); // 把下载好的图片保存到缓存中

					Files.saveImage(urls, data);

				} else

				{	//本地读取图片数据

					byte[] data = Files.readImage(urls);

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

					opt.inPreferredConfig = Bitmap.Config.RGB_565;

					opt.inPurgeable = true;

					opt.inInputShareable = true;

					// //获取资源图片

					// InputStream is =

					// context.getResources().openRawResource(resId);

					// return BitmapFactory.decodeStream(is,null,opt);

					bitmap = BitmapFactory.decodeByteArray(data, 0, data.length, opt);

					imagesCache.put(urls, bitmap); // 把下载好的图片保存到缓存中

				}

方法二：

class DownLoadTask extends AsyncTask<String, Void, Bitmap> {

		private ImageView imageView;

		private Integer positions;

		public DownLoadTask(ImageView view, int position) {

			imageView = view;

			this.positions = position;

		}

		protected Bitmap doInBackground(String... params) {

			URL url;

			try {

				url = new URL(params[0]);

				InputStream is = url.openStream();

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

				opt.inPreferredConfig = Bitmap.Config.RGB_565;

				opt.inPurgeable = true;

				opt.inInputShareable = true;

				// 获取资源图片

				Bitmap bitmap = BitmapFactory.decodeStream(is, null, opt);

				HomeActivity.TopGalleryBitmap.put(positions, bitmap);

				return bitmap;

			} catch (OutOfMemoryError err) {

				err.printStackTrace();

			} catch (MalformedURLException e) {

				e.printStackTrace();

			} catch (IOException e) {

				e.printStackTrace();

			}

			return null;

		}

		protected void onPostExecute(Bitmap result) {

			super.onPostExecute(result);

			imageView.setImageBitmap(result);

		}

	}