onResponse 函数中的改进响应 return null（单个 JSON 对象）

Question

我尝试在注册用户后从改装 API 中获得响应。

我从 response.body() 函数

中得到 null

注册URL：https://apitest10101.000webhostapp.com/alaa-apii/public/createuser（方法POST）

API return 单个对象 JSON 喜欢

{
    "error": true,
    "message": "User Already Exists"
}

"response work after tested in postman"

RegisterActivity.java

public void register(View view) {

       if(Validate())
       {
           Log.d("####", "OKAAAAAY");

            first_name = first_name_edit.getText().toString().trim();
            last_name = last_name_edit.getText().toString().trim();
            email = email_edit.getText().toString().trim();
            password = password_edit.getText().toString().trim();
            phone = Integer.parseInt(phone_edit.getText().toString().trim());
            state = state_edit.getText().toString().trim();
            block = block_edit.getText().toString().trim();
            street = street_edit.getText().toString().trim();
            building = buidling_edit.getText().toString().trim();
            floor = floor_edit.getText().toString().trim();
            flat = flat_edit.getText().toString().trim();


          Call<ResultModel> call = RetrofitClient
                .getInstance()
                .getApi()
                .createUser(first_name, last_name, email, password, phone, postionOfReigon, state, block, street, building, floor, flat);

          call.enqueue(new Callback<ResultModel>() {
              @Override
              public void onResponse(Call<ResultModel> call, Response<ResultModel> response) {

                  boolean error = false;
                  String mass = null;
                  if (response.body() != null) { // response null  !!!!!!!!!!!
                      error = response.body().getError();
                      mass = response.body().getMessage();
                      Log.d("#####", error + "------" + mass);
                  }


                      Log.d("#####", error + "------" + mass);

              }

              @Override
              public void onFailure(Call<ResultModel> call, Throwable t) {
                  Toast.makeText(RegisterActivity.this, t.getMessage(), Toast.LENGTH_LONG).show();

              }
          });


       }
       else
       {
           Log.d("####", "NNNOOTT OKAAAAAY");
       }

    }

如果我删除 response.body() 中的 if 语句，我会在日志

中收到此错误

2019-11-10 12:45:51.242 21211-21211/com.example.myapplication E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.myapplication, PID: 21211
    java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Boolean com.example.myapplication.ResultModel.getError()' on a null object reference
        at com.example.myapplication.RegisterActivity.onResponse(RegisterActivity.java:161)
        at retrofit2.DefaultCallAdapterFactory$ExecutorCallbackCall.run(DefaultCallAdapterFactory.java:83)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6718)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

ResultModel.java

package com.example.myapplication;

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

public class ResultModel {

    @SerializedName("error")
    @Expose
    private Boolean error;
    @SerializedName("message")
    @Expose
    private String message;

    public ResultModel(Boolean error, String message) {
        this.error = error;
        this.message = message;
    }

    public Boolean getError() {
        return error;
    }

    public void setError(Boolean error) {
        this.error = error;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

}

RetrofitClient.java

package com.example.myapplication;

import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;

public class RetrofitClient {

    private  static final String BASE_URL = "https://apitest10101.000webhostapp.com/alaa-apii/public/";
    private static RetrofitClient mInstance;
    private Retrofit retrofit;

    private RetrofitClient(){
        retrofit = new Retrofit.Builder()
                .baseUrl(BASE_URL)
                .addConverterFactory(GsonConverterFactory.create())
                .build();
    }

    public static synchronized RetrofitClient getInstance()
    {
        if(mInstance == null)
        {
            mInstance = new RetrofitClient();
        }
        return mInstance;
    }

    public Api getApi()
    {
        return retrofit.create(Api.class);
    }



}

API接口

package com.example.myapplication;


import retrofit2.Call;
import retrofit2.http.Field;
import retrofit2.http.FormUrlEncoded;
import retrofit2.http.POST;

public interface Api {


    @FormUrlEncoded
    @POST("createuser")
    Call<ResultModel> createUser(
            @Field("firstname") String firstname,
            @Field("lastname") String lastname,
            @Field("email") String email,
            @Field("password") String password,
            @Field("phone") int phone,
            @Field("region") int region,
            @Field("state") String state,
            @Field("block") String block,
            @Field("street") String street,
            @Field("building") String building,
            @Field("floor") String floor,
            @Field("flat") String flat
    );
}

建设gradle

implementation 'com.squareup.retrofit2:retrofit:2.6.2'
implementation 'com.squareup.retrofit2:converter-gson:2.6.2'

getError() 应该 return false or true 和 getMessage() 应该 return 消息 User Already Exists 或 User created successfully .

我使用slim framework v3.12搭建api.

** 任何建议 **

Answer 1

您似乎获得 422 作为 http 状态。所有不是 2XX 状态代码的内容都被改造视为错误，在这种情况下，您可以使用 response.errorBody().

访问它

不太好的消息是它必须手动转换。一种方法是使用 response.errorBody().string().

确保只调用一次，因为第一次读取后它将不再可读。这是一种流式行为。

Answer 2

您得到的响应代码是 422，如果后端和前端同意此代码不是错误，那么您可以通过创建自定义 Interceptor 并让它保持 return 当您获得该响应代码时得到的响应，只需确保将 Interceptor 添加到您的 Retrofit client

onResponse 函数中的改进响应 return null（单个 JSON 对象）

Retrofit response return null in onResponse function (single JSON object)

java

api

android

retrofit

slim-3