java中post推送json格式字符串

最近项目中遇到post推送json格式字符串，之前写过推送json数据，调用失败，才发现是直接推送字符串，只不过字符串是json的格式。

在postman中调用如下：

Java中代码如下：

/**
    * 发送POST方法的请求
    * @param url 发送请求的 URL
    * @param jsonData 请求参数是Json格式字符串
    * @return 响应结果
    */
   public static String sendPostJsonStr(String url, String jsonData) {
       PrintWriter out = null;
       BufferedReader in = null;
       String result = "";
       try {
           HttpClient client = new HttpClient();
           PostMethod postMethod = new PostMethod(url);
           postMethod.addRequestHeader("Content-type", "application/json; charset=utf-8");
           byte[] requestBytes = jsonData.getBytes("utf-8"); // 将参数转为二进制流
           InputStream inputStream = new ByteArrayInputStream(requestBytes, 0, requestBytes.length);
           // 请求体
           RequestEntity requestEntity = new InputStreamRequestEntity(inputStream, requestBytes.length, "application/json; charset=utf-8");
           postMethod.setRequestEntity(requestEntity); // 将参数放入请求体
           client.executeMethod(postMethod);
           inputStream = postMethod.getResponseBodyAsStream();
           BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
           StringBuffer stringBuffer = new StringBuffer();
           String str= "";
           while((str = br.readLine()) != null){
               stringBuffer.append(str);
           }
           result=stringBuffer.toString();
       } catch (Exception e) {
           e.printStackTrace();
       }
       finally {
           try {
               if (out != null) {
                   out.close();
               }
               if (in != null) {
                   in.close();
               }
           } catch (IOException ex) {
               ex.printStackTrace();
           }
       }
       return result;
   }