java - 改造响应在 onResponse 函数中返回 null(单个 JSON 对象)

Question

我尝试在注册用户后从改进 API 获取响应。

我从 response.body() 函数中得到 null

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

API 返回单个对象 JSON，如

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

“在 postman 中测试后的响应工作”

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$2.onResponse(RegisterActivity.java:161)
        at retrofit2.DefaultCallAdapterFactory$ExecutorCallbackCall$1$1.run(DefaultCallAdapterFactory.java:83)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6718)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$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(interface)

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
    );
}

构建gradle

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

getError() 应返回 false 或 true，getMessage()应返回消息用户已存在或用户创建成功。

我使用 slim 框架 v3.12 来构建 api。

**任何建议**

Answer 1

您似乎获得了 422 作为 http 状态。所有不是 2XX 状态代码的内容都会被改造视为错误，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。这是一种类似流的行为。