Question

我正在尝试将JSON（myJson.json）对象转换为Java类。

使用以下How to convert Java Object to From Json Jackson @Mykong代码。

  //2. Convert JSON to Java object
   ObjectMapper mapper = new ObjectMapper();
   StudentInfoDTO student = mapper.readValue(new File("c:\\myJson.json"), StudentInfoDTO.class);

但上述ObjectMapper为unable to map the Parent(StudentDTO) Class Properties(loggedInUser,createdBy,...).

是否还有@annotations可以映射父类属性。

欢迎任何建议。

我有以下内容 - StudentInfoDTO，AddressDTO，StudentDTO，SkillsDTO和myJson.json。

StudentInfoDTO：

public class StudentInfoDTO extends StudentDTO implements Serializable{
private static final long serialVersionUID = 1L;
private AddressDTO address;
private String studentName;
....getters and setters

}

AddressDTO：

 public class AddressDTO implements Serializable{
    private static final long serialVersionUID = 1L;
    private String street;
    private String city;
    private String state;
    private String country;
    private Long zipcode;
    ....getters and setters

    }

StudentDTO：

 public class StudentDTO implements Serializable{
    private static final long serialVersionUID = 1L;
    private String loggedInUser;
    private String createdBy;
    private Date createdTs;
    private String updatedBy;
    private Date updatedTs;
    private List<skillsDTO> skills;
    ....getters and setters

    }

myJson.json

 {
   "address": 
      {
        "street": "Hunterfly Place",
        "city": "Dunlo",
        "state": "Arizona",
        "country": "Colorado",
        "zipcode": "1631",
      },
    "studentName": "John",

    "loggedInUser": "Admin",
    "createdBy": "System",
    "createdTs": "03-19-2011 14:53",
    "updatedBy": "John",
    "updatedTs": "06-11-2014 08:00",
    "skills": [
        {
            "skill": "Football",
            "grade": "A"
        },
        {
            "skill": "Swimming",
            "grade": "C"
        },
        {
            "skill": "Dance",
            "grade": "A"
        }]

    }

我的错误日志：

03:29:03,132 ERROR [stderr] (http-localhost-127.0.0.1-8080-2) org.codehaus.jackson.map.exc.UnrecognizedPropertyException: Unrecognized field "loggedInUser" (Class com.mySchool.project.services.StudentInfoDTO), not marked as ignorable
03:29:03,133 ERROR [stderr] (http-localhost-127.0.0.1-8080-2)  at [Source: c:\myJson.json; line: 51, column: 23] (through reference chain: com.mySchool.project.services.StudentInfoDTO["address"]->com.mySchool.project.services.StudentInfoDTO["loggedInUser"])

03:29:03,133 ERROR [stderr] (http-localhost-127.0.0.1-8080-2)   at org.codehaus.jackson.map.exc.UnrecognizedPropertyException.from(UnrecognizedPropertyException.java:53)

03:29:03,134 ERROR [stderr] (http-localhost-127.0.0.1-8080-2)   at org.codehaus.jackson.map.deser.StdDeserializationContext.unknownFieldException(StdDeserializationContext.java:246)

Answer 1

基本上您正在尝试从StudentInfoDTO读取，但此类没有关于StudentDTO的信息。您需要更改一些代码（添加学生参数）：

public class StudentInfoDTO implements Serializable{
     private static final long serialVersionUID = 1L;
     private AddressDTO address;
     private StudentDTO student;
     ....getters and setters
 }

你的JSON应该是这样的：

{
   "address": 
      {
        "street": "Hunterfly Place",
        "city": "Dunlo",
        "state": "Arizona",
        "country": "Colorado",
        "zipcode": "1631",
      },
    "student":
      {
        "studentName": "John",

        "loggedInUser": "Admin",
        "createdBy": "System",
        "createdTs": "03-19-2011 14:53",
        "updatedBy": "John",
        "updatedTs": "06-11-2014 08:00",
            "skills": [
                {
                "skill": "Football",
                "grade": "A"
                }
       ...
      }
}

请注意，我在StudentDTO课程中添加了学生姓名。但这个想法仍然是一样的。您需要在JSON和类中具有相同的结构。

如果您无法更改JSON输出，只需更改类结构即可。例如，StudentInfoDTO具有“studentName”属性，并且还可能包括同一级别中的所有其他属性，如“loggedInUser”。您的解析器可能使用以下类：

public class StudentInfoDTO implements Serializable{
    private static final long serialVersionUID = 1L;
    private AddressDTO address;
    private String studentName;
    private String loggedInUser;
    private String createdBy;
    private Date createdTs;
    private String updatedBy;
    private Date updatedTs;
    private List<skillsDTO> skills;
    ...

}

使用最后一种方法，您不需要StudentDTO课程。

如果您想使用扩展程序，那么您可能会更改超类的可见性：

public class StudentDTO implements Serializable{
    private static final long serialVersionUID = 1L;
    protected String loggedInUser;
    protected String createdBy;
    protected Date createdTs;
    protected String updatedBy;
    protected Date updatedTs;
    protected List<skillsDTO> skills;

    public StudentDTO () {}

    ....getters and setters
}

Answer 2

抱歉方便。

它按预期工作。我的myJson.json文件出错了，我按照@Vishvesh Phadnis

的建议重新生成了Getters和Setters

{
   "address": 
      {
        "street": "Hunterfly Place",
        "city": "Dunlo",
        "state": "Arizona",
        "country": "Colorado",
        "zipcode": "1631"
      },
    "studentName": "John",

    "loggedInUser": "Admin",
    "createdBy": "System",
    "createdTs": "03-19-2011 14:53",
    "updatedBy": "John",
    "updatedTs": "06-11-2014 08:00",
    "skills": [
        {
            "skill": "Football",
            "grade": "A"
        },
        {
            "skill": "Swimming",
            "grade": "C"
        },
        {
            "skill": "Dance",
            "grade": "A"
        }]

    }

全部谢谢：）

Jackson：忽略父类属性：将json反序列化为数据

2 个答案: