ws客户端连接服务端连接创建

public static String callSsoRestfulApi(String req_url) {
StringBuffer buffer = new StringBuffer();
try {
URL url = new URL(req_url);
HttpURLConnection httpUrlConn = (HttpURLConnection) url.openConnection();

        httpUrlConn.setDoOutput(false);
        httpUrlConn.setDoInput(true);
        httpUrlConn.setUseCaches(false);

        httpUrlConn.setRequestMethod("GET");
        httpUrlConn.connect();

        InputStream inputStream = httpUrlConn.getInputStream();
        InputStreamReader inputStreamReader = new InputStreamReader(inputStream, StandardCharsets.UTF_8);
        BufferedReader bufferedReader = new BufferedReader(inputStreamReader);

        String str = null;
        while ((str = bufferedReader.readLine()) != null) {
            buffer.append(str);
        }
        bufferedReader.close();
        inputStreamReader.close();
        inputStream.close();
        inputStream = null;
        httpUrlConn.disconnect();

    } catch (Exception e