httpclient用post方式发送json乱码错误解决

public static String doPostByJson(String url, JSONObject json){

    CloseableHttpClient httpclient = HttpClientBuilder.create().build();
    HttpPost post = new HttpPost(url);
    String response = null;
    try {
        StringEntity s = new StringEntity(json.toString(),"utf-8");        //这里是关键,后面要跟上字符集格式
        s.setContentEncoding("UTF-8");
        s.setContentType("application/json");//发送json数据需要设置contentType
        post.setEntity(s);
        HttpResponse res = httpclient.execute(post);
        if(res.getStatusLine().getStatusCode() == HttpStatus.SC_OK){
            String result = EntityUtils.toString(res.getEntity());// 返回json格式：
            response = result;
        }
    } catch (Exception e) {
        throw new RuntimeException(e);
    }
    return response;
}

之前直接用然后接受乱码,发现在设置字符串对象的时候需要写汉字编码字符集格式.