将Java字段映射到JSON文档根目录

Question

I couldn't find an example how to map the following json:

{
"id":1,
"name":"hugodesmarques",
"age":30,
}

To the following java object using jackson:

public class EntityDto {
   private Map<String, Object> content;
}

Notice the dto is just a wrapper. What I'm trying to achieve is to have an object EntityDto with a Map{name=>"hugodesmarques", age=>30, id=>1}.

I want to avoid having to map each json field to an object map.

Answer 1

Structure of class must be like structure of JSON:

public class EntityDto {
   int id;
   String name;
   int age;
}

Answer 2

Jackson can read JSON as a HashMap:

    ObjectMapper mapper = new ObjectMapper();
    Map<String, Object> map = mapper.readValue("{\"id\":1, \"name\": \"One\"}", HashMap.class);
    EntityDto dto = new EntityDto();
    dto.setContent(map);

Answer 3

A step back

First of all, the JSON you posted in you question is invalid : there's a comma after 30 and it shouldn't be there. Fix your JSON otherwise Jackson won't parse it:

{
  "id": 1,
  "name": "hugodesmarques",
  "age": 30
}

Parsing the JSON with Jackson

Add a constructor annotated with @JsonCreator to the EntityDto class, as following:

public class EntityDto {

    private Map<String, Object> content;

    @JsonCreator
    public EntityDto(Map<String, Object> content) {
        this.content = content;
    }

    // Getters and setters omitted
}

Then parse the JSON using ObjectMapper :

String json = "{\"id\":1,\"name\":\"hugodesmarques\",\"age\":30}";

ObjectMapper mapper = new ObjectMapper();
EntityDto entityDto = mapper.readValue(json, EntityDto.class);