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java - 如何将下面的 Json 转换为 Java Pojo 类？

问题描述

请在 Json 下方查看。我想将其转换为 POJO 类。

我已经尝试过以下课程

@Data
public class Root {
    @JsonProperty("0")      // Dont want to pass like this. it should be single list and index is the key of that array
    public List<Request> list;
    @JsonProperty("1")
    public List<Request> list1;
    @JsonProperty("2")
    public List<Request> list2;

    @Data
    private class Request {
        int id;
        String title;
        int level;
        List<Request> children;
        @JsonProperty("parent_id")
        int parentId;
    }
}

{
  "0": [
    {
      "id": 12123,
      "title": "sfsdf",
      "level": 0,
      "children": [
        
      ],
      "parent_id": null
    }
  ],
  "1": [
    {
      "id": 213,
      "title": "d",
      "level": 1,
      "children": [
        
      ],
      "parent_id": 1212312
    },
    {
      "id": 3232,
      "title": "dfsdf",
      "level": 1,
      "children": [
        
      ],
      "parent_id": 42
    },
    {
      "id": 234,
      "title": "tder",
      "level": 1,
      "children": [
        
      ],
      "parent_id": 122
    }
  ],
  "2": [
    {
      "id": 452,
      "title": "Blll",
      "level": 2,
      "children": [
        
      ],
      "parent_id": 322
    },
    {
      "id": 123,
      "title": "trrr",
      "level": 11,
      "children": [
        
      ],
      "parent_id": 1221
    },
    {
      "id": 33,
      "title": "sdfw",
      "level": 2123,
      "children": [
        
      ],
      "parent_id": 10
    }
  ]
}

标签： javajsonspringspring-boot

解决方案

使用@JsonAnySetter.

示例，public为简单起见使用字段：

class Root {
    @JsonAnySetter
    public Map<String, List<Request>> lists = new LinkedHashMap<>();
}

class Request {
    public int id;
    public String title;
    public int level;
    public List<Request> children;
    @JsonProperty("parent_id")
    public Integer parentId; // 'Integer', not 'int', since it can be null
}

测试

ObjectMapper mapper = new ObjectMapper();
Root root = mapper.readValue(new File("test.json"), Root.class);
for (Entry<String, List<Request>> entry : root.lists.entrySet()) {
    System.out.println(entry.getKey() + ":");
    for (Request request : entry.getValue()) {
        System.out.println("  id=" + request.id +
                        ", title=" + request.title +
                        ", level=" + request.level +
                     ", children=" + request.children +
                     ", parentId=" + request.parentId);
    }
}

输出

0:
  id=12123, title=sfsdf, level=0, children=[], parentId=null
1:
  id=213, title=d, level=1, children=[], parentId=1212312
  id=3232, title=dfsdf, level=1, children=[], parentId=42
  id=234, title=tder, level=1, children=[], parentId=122
2:
  id=452, title=Blll, level=2, children=[], parentId=322
  id=123, title=trrr, level=11, children=[], parentId=1221
  id=33, title=sdfw, level=2123, children=[], parentId=10

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