okhttp3.8 post json android发送json字符问题

JSONObject obj = new JSONObject();
obj.put("uname",uname);
obj.put("pwd",pwd);
GetPostUtil gp = new GetPostUtil();
String res = gp.post("http://192.168.0.102:8000/dologin/", obj.toString());

提交成功后
POST:,

服务器端的post打印出来，怎么整个字符串都做一个键的值了。这个是怎么回事，那位大侠知道

构造RequestBody的时候，指定JSON类型

RequestBody body = RequestBody.create(JSON, obj.toString());

指定了的
OkHttpClient client = new OkHttpClient();
public static final MediaType JSON
= MediaType.parse("application/json; charset=utf-8");
private String result=null;
public String post(String url, String json) throws IOException {
Log.i("json","--------"+json);
//把请求的内容字符串转换为json
RequestBody body = RequestBody.create(JSON, json);

    Log.i("json","--------"+body);
    //RequestBody formBody = new FormEncodingBuilder()


    final Request request = new Request.Builder()
            .url(url)
            .post(body)
            .build();
    final Call call = client.newCall(request);

    Response response = call.execute();

    if(response.isSuccessful()){
        result = response.body().string();
    }else{
        throw new IOException("Unexpected code " + response);
    }

    Log.i("result","--------"+result);
    return result;


}