android客户端程序连接服务器总是失败，出现IOException

下面这段代码在程序中运行出现IOException

        /**
	 * 下载线程
	 */
	private Runnable runnable = new Runnable() {
		@Override
		public void run() {
			// TODO Auto-generated method stub
			try {
				URL url = new URL(apkUrl);
				HttpURLConnection conn = (HttpURLConnection) url
						.openConnection();
				conn.connect();
				int length = conn.getContentLength();
				InputStream is = conn.getInputStream();
				File file = new File(savePath);
				if (!file.exists()) {
					file.mkdir();
				}
				String apkFile = saveFileName;
				File ApkFile = new File(apkFile);
				FileOutputStream fos = new FileOutputStream(ApkFile);
				int count = 0;
				byte buf[] = new byte[1024];
				do {
					int numread = is.read(buf);
					count += numread;
					progress = (int) (((float) count / length) * 100);
					// 更新进度条
					mHandler.sendEmptyMessage(DOWN_UPDATE);
					if (numread <= 0) {
						// 下载完成通知
						mHandler.sendEmptyMessage(DOWN_OVER);
						break;
					}
					fos.write(buf, 0, numread);
				} while (!interceptFlag);
				fos.close();
				is.close();
			} catch (MalformedURLException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}

	};

折腾半天，原来是粗心大意，忘记了android的两个权限：

加上后客户端与服务器连接正常，IO流读取正常。