如何在retrofit2 android中发送表单数据

嗨我有一个json发送到服务器(POST METHORD){“country”：“india”,“devicetype”：“ android”}它是在表单数据模型
像这个json的关键是数据,即服务器接受它

data = {“country”：“india”,“devicetype”：“android”}我正在使用改装我使用Multipart这样

@Multipart
@POST("initiate")
@Headers({
        "Content-Type: application/json","Cache-Control: no-cache"
})
Call<UserInfoServerResponse> getUserInfoRequest(@Part(value="data") UserInfo mUserInfo);

这里UserInfo是json但是在我使用FormUrlEncoded methord后从服务器收到失败消息

@FormUrlEncoded
@POST("initiate")
@Headers({
        "Content-Type: application/json","Cache-Control: no-cache"
})
Call<UserInfoServerResponse> getUserInfoRequest(@Field(value="data",encoded = false) String mUserInfo);

它的输出也是服务器的相同故障结果,但发送到服务器的数据是合成的

data=%7B%22country%22%3A%22india%22%2C%22devicetype%22%3A%22%22%7D

我的UserInfo.class

public class UserInfo {


public String country;

public String devicetype;

public UserInfo( String country,String devicetype) {

    this.country=country;

    this.devicetype=devicetype;
}
}

我的适配器类

RemoteRetrofitInterfaces mService;
    Retrofit mRetrofit;
  HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
        interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);

        OkHttpClient client = new OkHttpClient.Builder()
                .connectTimeout(20,TimeUnit.SECONDS)
                .writeTimeout(20,TimeUnit.SECONDS)
                .readTimeout(30,TimeUnit.SECONDS).addInterceptor(interceptor)
                .build();

        mRetrofit = new Retrofit.Builder()
                .baseUrl(AppConstant.HOST).addConverterFactory(GsonConverterFactory.create())
                .client(client)
                .build();
        mService = mRetrofit.create(RemoteRetrofitInterfaces.class);

   Call<UserInfoServerResponse> api = mService.getUserInfoRequest(new Gson().toJson(mUserInfo));

        api.enqueue(new Callback<UserInfoServerResponse>() {
            @Override
            public void onResponse(Call<UserInfoServerResponse> responseCall,Response<UserInfoServerResponse> response) {

                if (response.body().status != null) {
                    if (response.body().status.equals("success")) {
                        Log.d(TAG,"success---");
                    }

                } else {
                    Log.d(TAG,"Failed---");

                }


            }

            @Override
            public void onFailure(Call<UserInfoServerResponse> responseCall,Throwable t) {
                t.printstacktrace();
            }


        });

所以我怎么能成功地使用改装将json发送到服务器我经历了retofit document并且遵循了几个步骤但我没有得到任何结果.任何人都可以帮助我

谢谢

@POST("initiate")
@FormUrlEncoded

Call<UserInfoServerResponse> getUserInfoRequest(@FieldMap Map<String,String> params);

Log.d(TAG,"sendUserInfo called");
UserInfo mInfo=new UserInfo("countyname","android");
        String request=new Gson().toJson(mUserInfo);

        //Here the json data is add to a hash map with key data
        Map<String,String> params = new HashMap<String,String>();
        params.put("data",request);


        Call<UserInfoServerResponse> api = mService.getUserInfoRequest(params);


        api.enqueue(new Callback<UserInfoServerResponse>() {
            @Override
            public void onResponse(Call<UserInfoServerResponse> responseCall,"success---" + response.body());
                    }

                } else {
                    Log.d(TAG,Throwable t) {
                t.printstacktrace();
            }


        });