从http中获得 Inputstream

/**     * 从http中获得 Inputstream     *     * @param url http地址     * @return inputstream     * @throws java.io.IOException IOException     */    private static InputStream getInputStreamFromHttp(String url) throws IOException {        URL downUrl = new URL(url);        HttpURLConnection connection = (HttpURLConnection)downUrl.openConnection();        connection.connect();        if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {            return connection.getInputStream();        }        return null;    }