JAVA复杂对象与JSON的转换

最新推荐文章于 2023-02-14 14:13:51 发布

原创最新推荐文章于 2023-02-14 14:13:51 发布 · 1.9k 阅读

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文章标签：

#json #数据库 #java

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1.背景

JSON可以用文本格式存储对象，比如前后端交互过程中传输DTO。现在我的需求是接收到的DTO中除了常见属性外，还有较复杂的List，甚至有多层List嵌套。这个字段除了save和retrieve外不做修改，也不会作为查询时的条件，所以为了方便起见，将整个list作为一个json存入数据库，MySQL5.7开始支持这一类型的栏位

2.工具

我使用的是阿里巴巴的fastjson作为JSON转换的工具

3.代码

3.1Entity

PersonEntity

@Data
@AllArgsConstructor
@NoArgsConstructor
public class PersonEntity {
    private String name;
    private String age;
    private String works;
}

Person实体有姓名和年龄这两个常用属性，和works这个属性

3.2DTO

PersonDTO

@Data
@NoArgsConstructor
@AllArgsConstructor
public class PersonDTO {
    private String name;
    @NotBlank
    private String age;
    @Valid
    @NotEmpty
    @JsonProperty("works")
    private List<WorkDTO> works;
}

PersonDTO中works为List，且类型为WorkDTO

WorkDTO

@Data
@NoArgsConstructor
@AllArgsConstructor
public class WorkDTO {
    @NotNull
    private String place;
    @Valid
    @NotEmpty
    @JsonProperty("activities")
    private List<ActivityDTO> activities;
}

WorkDTO中activity也是list

ActivityDTO

@Data
@NoArgsConstructor
@AllArgsConstructor
public class ActivityDTO {
    public static final ActivityDTO NULL = new ActivityDTO("", 0);

    @NotNull
    private String alias;
    private Integer duration;
}

3.3准备数据

@Test
    void contextLoads() {
        PersonDTO personDTO = new PersonDTO();
        ArrayList<WorkDTO> workDTOS = new ArrayList<>();
        for (int i = 0; i < 5; i++) {
            WorkDTO workDTO = new WorkDTO();
            ArrayList<ActivityDTO> activityDTOS = new ArrayList<>();
            for (int j = 0; j < 3; j++) {
                ActivityDTO activityDTO = new ActivityDTO();
                activityDTO.setAlias("action:" + j);
                activityDTO.setDuration(j);
                activityDTOS.add(activityDTO);
            }
            workDTO.setPlace("place:" + i);
            workDTO.setActivities(activityDTOS);
            workDTOS.add(workDTO);
        }
        personDTO.setWorks(workDTOS);
        personDTO.setName("skye");
        personDTO.setAge("20");

        System.out.println("-----------------------------------------------------------------------------------------------------------");
        System.out.println("最初的personDTO:" + personDTO);
        System.out.println("最初的personDTO的works，应当为List<>:" + personDTO.getWorks());

        PersonEntity personEntity = personDTOToEntity(personDTO);
        System.out.println("-----------------------------------------------------------------------------------------------------------");
        System.out.println("personDTO转化为personEntity:" + personEntity);
        System.out.println("personDTO转化为personEntity的works，应当为String:" + personEntity.getWorks());

        PersonDTO personDTO1 = personEntityToDTO(personEntity);
        System.out.println("-----------------------------------------------------------------------------------------------------------");
        System.out.println("personEntity转化为personDTO1:" + personDTO1);
        System.out.println("personEntity转化为personDTO1的works，应当为List<>:" + personDTO1.getWorks());
    }

3.4转换方法

DTO TO ENTITY

    private PersonEntity personDTOToEntity(PersonDTO personDTO) {
        PersonEntity personEntity = new PersonEntity();
        personEntity.setName(personDTO.getName());
        personEntity.setAge(personDTO.getAge());
        //personEntity.setWorks(String.valueOf(personDTO.getWorks()));
        personEntity.setWorks(JSONArray.toJSONString(personDTO.getWorks()));
        return personEntity;
    }

将List转化为String的过程中不可以使用String.valueof，这个方法转化出来的String不是JSON格式

ENTITY TO DTO

    private PersonDTO personEntityToDTO(PersonEntity personEntity) {
        PersonDTO personDTO = new PersonDTO();
        personDTO.setName(personEntity.getName());
        personDTO.setAge(personEntity.getAge());
        List<WorkDTO> workDTOS = JSONArray.parseArray(personEntity.getWorks(),WorkDTO.class);
        personDTO.setWorks(workDTOS);
       return personDTO;
    }

JSONObject可以直接将JSON转化为List

4.结果

-----------------------------------------------------------------------------------------------------------
最初的personDTO:PersonDTO(name=skye, age=20, works=[WorkDTO(place=place:0, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:1, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:2, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:3, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:4, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)])])
最初的personDTO的works，应当为List<>:[WorkDTO(place=place:0, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:1, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:2, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:3, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:4, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)])]
-----------------------------------------------------------------------------------------------------------
personDTO转化为personEntity:PersonEntity(name=skye, age=20, works=[{"activities":[{"alias":"action:0","duration":0},{"alias":"action:1","duration":1},{"alias":"action:2","duration":2}],"place":"place:0"},{"activities":[{"alias":"action:0","duration":0},{"alias":"action:1","duration":1},{"alias":"action:2","duration":2}],"place":"place:1"},{"activities":[{"alias":"action:0","duration":0},{"alias":"action:1","duration":1},{"alias":"action:2","duration":2}],"place":"place:2"},{"activities":[{"alias":"action:0","duration":0},{"alias":"action:1","duration":1},{"alias":"action:2","duration":2}],"place":"place:3"},{"activities":[{"alias":"action:0","duration":0},{"alias":"action:1","duration":1},{"alias":"action:2","duration":2}],"place":"place:4"}])
personDTO转化为personEntity的works，应当为String:[{"activities":[{"alias":"action:0","duration":0},{"alias":"action:1","duration":1},{"alias":"action:2","duration":2}],"place":"place:0"},{"activities":[{"alias":"action:0","duration":0},{"alias":"action:1","duration":1},{"alias":"action:2","duration":2}],"place":"place:1"},{"activities":[{"alias":"action:0","duration":0},{"alias":"action:1","duration":1},{"alias":"action:2","duration":2}],"place":"place:2"},{"activities":[{"alias":"action:0","duration":0},{"alias":"action:1","duration":1},{"alias":"action:2","duration":2}],"place":"place:3"},{"activities":[{"alias":"action:0","duration":0},{"alias":"action:1","duration":1},{"alias":"action:2","duration":2}],"place":"place:4"}]
-----------------------------------------------------------------------------------------------------------
personEntity转化为personDTO1:PersonDTO(name=skye, age=20, works=[WorkDTO(place=place:0, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:1, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:2, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:3, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:4, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)])])
personEntity转化为personDTO1的works，应当为List<>:[WorkDTO(place=place:0, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:1, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:2, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:3, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)]), WorkDTO(place=place:4, activities=[ActivityDTO(alias=action:0, duration=0), ActivityDTO(alias=action:1, duration=1), ActivityDTO(alias=action:2, duration=2)])]