httpclient 发送 json数据，微信security.msgSecCheck，

/**
     * post请求
     * @param url
     * @param json
     * @return
     */
    public static JSONObject doPost(String url,JSONObject json){
        
        CloseableHttpClient httpclient = HttpClientBuilder.create().build();
        HttpPost post = new HttpPost(url);
        JSONObject response = null;
        try {
            StringEntity s = new StringEntity(json.toString(),"UTF-8");
            s.setContentEncoding("UTF-8");
            s.setContentType("application/json");//发送json数据需要设置contentType
            post.setEntity(s);
            System.out.println(post);
            HttpResponse res = httpclient.execute(post);
            if(res.getStatusLine().getStatusCode() == HttpStatus.SC_OK){
                String result = EntityUtils.toString(res.getEntity());// 返回json格式：
                response = JSONObject.fromObject(result);
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
        return response;
    }
    

<dependency>
  <groupId>net.sf.json-libgroupId>
  <artifactId>json-libartifactId>
  <version>2.4version>
  
  <classifier>jdk15classifier>
dependency>

org.apache.httpcomponents
httpclient
4.5.6

Map contentmap = new HashMap();

contentmap.put("content", "xidada");

JSONObject json = JSONObject.fromObject(contentmap);

System.out.println("json is = "+json);
String msg = doPost(url, json).toString();