Retrofit2 和转换器-gson：预期 BEGIN_OBJECT 但在第 1 行第 1 列路径 $

Question

我已经阅读了针对此问题的先前解决方案mostly this one，但没有一个对我有用。 :(。在调试时，我发现了来自改造的原始请求数据，如下图所示，我突出显示了 2 个部分：

这里是第一个突出显示的部分，以原始 json 格式显示我的改造请求

{
  "operation": "register",
  "studentModel": {
    "batch_id": "cseuui",
    "dept_code": "CSE",
    "password": "p",
    "student_address": "tpc",
    "student_email": "foc@gxs.bv",
    "student_id": "tyjvc",
    "student_name": "jak",
    "student_phone": "87532"
  }
}

但这给了我第二个突出显示的错误部分：

Expected BEGIN_OBJECT but was STRING at line 1 column 1 path $

但是使用 postman 我能够成功地将这个原始 json 插入到数据库中。

{
  "operation": "register",
  "studentModel": {
    "batch_id": "cseuui",
    "dept_code": "CSE",
    "password": "p",
    "student_address": "tpc",
    "student_email": "foc@gxs.bv",
    "student_id": "tyjvc",
    "student_name": "jak",
    "student_phone": "87532"
  }
}

这意味着我的服务器端没问题。
我还有什么遗漏的吗？
我在下面给出我的一些代码，

Retrofit2 和 Gson 依赖：

compile 'com.squareup.retrofit2:retrofit:2.1.0'  
compile 'com.squareup.retrofit2:converter-gson:2.1.0'

StudentModel.java

Server request and response

Retrofit Client and ApiInterface

最后

Registration Method

由于我的服务器端与邮递员完美配合，我在这里缺少什么。请告诉我。

Answer 1

最后我解决了这个问题，只是将学生模型类变量名更改为我的数据库列名，并且我还删除了类定义中的@SerializedName("result") @Expose 映射。 实际上数据库列名与我的类变量不匹配。 谢谢大家，辛苦了。

Answer 2

改造获得无效的 JSON 响应

尝试从服务器的这个字符串Fromat中发送响应

         Gson gson = new Gson();
         response=gson.toJson(courseList);
         JsonObject myObj = new JsonObject();

         myObj.addProperty("operation", "register");

         myObj.add("studentModel",data);

         response = myObj.toString();

return responce;

改造建造者

retrofit =new Retrofit.Builder()
                    .baseUrl(BASE_URL)
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();

Answer 3

您正在尝试访问数组，但 Gson 在第一行找到了一个字符串。

所以你需要更改模型类。

StudentModel.java

` 公共类 StudentModel {

private String operation;
private Student student;

public Rootjava(String operation, Student student) {
    this.operation = operation;
    this.student = student;
}

public String getOperation() {
    return operation;
}

public void setOperation(String operation) {
    this.operation = operation;
}

public Student getStudent() {
    return student;
}

public void setStudent(Student student) {
    this.student = student;
}

@Override
public String toString() {
    return "studentModel{" +
            "operation='" + operation + '\'' +
            ", student=" + student +
            '}';
}

private class Student{
    @SerializedName("dept_code")
    private String deptCode;
    @SerializedName("student_name")
    private String studentName;
    private String password;
    @SerializedName("batch_id")
    private String batchId;
    @SerializedName("student_phone")
    private String studentPhone;
    @SerializedName("student_address")
    private String studentAddress;
    @SerializedName("student_id")
    private String studentId;
    @SerializedName("student_email")
    private String studentEmail;

    public Student(String deptCode, String studentName,
                   String password, String batchId,
                   String studentPhone, String studentAddress,
                   String studentId, String studentEmail) {
        this.deptCode = deptCode;
        this.studentName = studentName;
        this.password = password;
        this.batchId = batchId;
        this.studentPhone = studentPhone;
        this.studentAddress = studentAddress;
        this.studentId = studentId;
        this.studentEmail = studentEmail;
    }

    public String getDeptCode() {
        return deptCode;
    }

    public void setDeptCode(String deptCode) {
        this.deptCode = deptCode;
    }

    public String getStudentName() {
        return studentName;
    }

    public void setStudentName(String studentName) {
        this.studentName = studentName;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getBatchId() {
        return batchId;
    }

    public void setBatchId(String batchId) {
        this.batchId = batchId;
    }

    public String getStudentPhone() {
        return studentPhone;
    }

    public void setStudentPhone(String studentPhone) {
        this.studentPhone = studentPhone;
    }

    public String getStudentAddress() {
        return studentAddress;
    }

    public void setStudentAddress(String studentAddress) {
        this.studentAddress = studentAddress;
    }

    public String getStudentId() {
        return studentId;
    }

    public void setStudentId(String studentId) {
        this.studentId = studentId;
    }

    public String getStudentEmail() {
        return studentEmail;
    }

    public void setStudentEmail(String studentEmail) {
        this.studentEmail = studentEmail;
    }

    @Override
    public String toString() {
        return "Student{" +
                "deptCode='" + deptCode + '\'' +
                ", studentName='" + studentName + '\'' +
                ", password='" + password + '\'' +
                ", batchId='" + batchId + '\'' +
                ", studentPhone='" + studentPhone + '\'' +
                ", studentAddress='" + studentAddress + '\'' +
                ", studentId='" + studentId + '\'' +
                ", studentEmail='" + studentEmail + '\'' +
                '}';
    }
}

}`

使用这个模型类。

你可以使用插件来生成这个 POJO 类。

Answer 4

试试这个：

您的接收字符串而不是 JsonObject。像此映射一样更改您的 ServerResponse 并将标头添加为 'application/json'

1.添加header header.put("Content-Type", "application/json");

private void registerProcess(String studentName, String studentAddress, String studentEmail, String studentPhone, String department, String batch_id, String student_id, String rePassword) {

        APIInterface appInterface = ApiClient.getClient().create(APIInterface.class);

        StudentModel student = new StudentModel();
        student.setStudent_name(studentName);
        student.setStudent_address(studentAddress);
        student.setStudent_email(studentEmail);
        student.setStudent_phone(studentPhone);
        student.setDept_code(department);
        student.setBatch_id(batch_id);
        student.setStudent_id(student_id);
        student.setPassword(rePassword);

        Log.e(TAG,student.toString());

        ServerRequest request = new ServerRequest();


        Map<String, String> header = new HashMap<>();
        header.put("Content-Type", "application/json");

        request.setOperation(Config_Ref.REGISTER_OPERATION);
        request.setStudentModel(student);

        Call<ServerResponse> response = appInterface.operation(request,header);

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

                if(response.isSuccessful()){

                    ServerResponse resp = response.body();
                    Toast.makeText(RegisterActivity.this, resp.getMessage()+" success", Toast.LENGTH_SHORT).show();
                    Log.e(TAG,resp.getMessage()+" success");
                }else{
                    Toast.makeText(RegisterActivity.this, response.message()+" not success", Toast.LENGTH_SHORT).show();
                    Log.e(TAG,response.message()+" not success");
                }
               /* Snackbar.make(fview, resp.getMessage(), Snackbar.LENGTH_LONG).show();*/

                //pDialog.dismiss();
            }

            @Override
            public void onFailure(Call<ServerResponse> call, Throwable t) {
                /*Snackbar.make(fview, t.getLocalizedMessage(), Snackbar.LENGTH_LONG).show();*/
                Toast.makeText(RegisterActivity.this, t.getLocalizedMessage()+" failed"+call.toString(), Toast.LENGTH_SHORT).show();

                Log.e(TAG,t.getLocalizedMessage()+" failed");
            }
        });


    }

2.ApiInterface.java

将标头添加为 json 格式 公共接口 ApiInterface {

    @POST("/iuk/api/credentials")
    Call<ServerResponse> operation(@Body ServerRequest request,@HeaderMap Map<String, String> header);
   }

3.ServerResponse.java

    public class ServerResponse {

    @SerializedName("result")
    @Expose
    private String result;
    @SerializedName("message")
    @Expose
    private String message;

    public String getResult() {
    return result;
    }

    public void setResult(String result) {
    this.result = result;
    }

    public String getMessage() {
    return message;
    }

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

    }

ApiClient.Java

public class ApiClient {

    private static final String BASE_URL = "https://xyz.000webhostapp.com";
    private static Retrofit retrofit = null;


    public static Retrofit getClient() {
        if (retrofit == null) {
            HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
            interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
            OkHttpClient client = new OkHttpClient.Builder().addInterceptor(new Interceptor() {
             @Override
            public Response intercept(Chain chain) throws IOException {
                Request.Builder requestBuilder = chain.request().newBuilder();
                requestBuilder.header("Content-Type", "application/json");
                return chain.proceed(requestBuilder.build());
               }
               })
                .connectTimeout(30, TimeUnit.MINUTES)
                .readTimeout(30, TimeUnit.MINUTES)
                .build();

            retrofit = new Retrofit.Builder()
                    .baseUrl(BASE_URL)
                    .client(client)
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
        }
        return retrofit;
    }

}

依赖关系

compile 'com.squareup.retrofit2:retrofit:2.3.0'
compile 'com.google.code.gson:gson:2.8.2'
compile 'com.squareup.retrofit2:converter-gson:2.3.0'
compile 'com.squareup.okhttp3:okhttp:3.9.0'
compile 'com.squareup.okhttp3:logging-interceptor:3.9.0'    

Answer 5

创建模型类简单而不是列表类型。

之后创建一个 String 变量操作并创建 studentModel 的内部类。

public class Main{

    @SerializeName("operation")
    private String operation;

    @SerializeName("StudentModel")
    private StudentModel studentModel;

}

然后生成getter setter