JSON.toJSONString无法传递boolean

在使用JSON.toJSONString转json格式的时候，后端是springboot，前端是vue，每次返回的User对象总是少一个字段state

User实体类：

public class User {
    

    private int id;
    private String username;
    private String password;
    private String email;
    private String role;
    private Boolean state;

接口：

@RequestMapping("/alluser")
@ResponseBody
public String getUserList(QueryInfo queryInfo) {
    
    int numbers = userDao.getUserCount("%" + queryInfo.getQuery() + "%");
    int pageStart = (queryInfo.getPageNum() - 1) * queryInfo.getPageSize();

    List<User> users = userDao.getAllUser("%" + queryInfo.getQuery() + "%",pageStart,queryInfo.getPageSize());

    HashMap<String, Object> res = new HashMap<>();
    res.put("numbers",numbers);
    res.put("data",users);

    String s = JSON.toJSONString(res);
    return s;
}

开始是按上面写的，发现state字段一直传不到前端，在网上找了很多方法，最后还是没能解决，后面听说springboot传数据给vue不需要转json，直接返回也可以接收，就改成下面这样了

@RequestMapping("/alluser")
@ResponseBody
public Map getUserList(QueryInfo queryInfo) {
    
    int numbers = userDao.getUserCount("%" + queryInfo.getQuery() + "%");
    int pageStart = (queryInfo.getPageNum() - 1) * queryInfo.getPageSize();

    List<User> users = userDao.getAllUser("%" + queryInfo.getQuery() + "%",pageStart,queryInfo.getPageSize());

    HashMap<String, Object> res = new HashMap<>();
    res.put("numbers",numbers);
    res.put("data",users);

    return res;
}

直接返回Map，在前端就可以接收到全部字段了

前端：

  data() {
    
    return {
    
      queryInfo: {
    
        query: "",
        pageNum: 1,
        pageSize: 10,
      },
      userList: [],
      total: null,
  },

  methods: {
    
    async getUserList() {
    
      const {
    data:res} = await this.$http.get("/alluser",{
    params: this.queryInfo});
      this.userList = res.data;
      this.total = res.numbers
    }
}

无法将state字段传递回去，具体原因还没找到，不管是改get、set，还是JSON.toJSONString的时候加那些参数，都不管用~