SpringBoot中@JsonFormat指定格式后ToDoDate字段无法解析日期

问题 #

开发SpringBoot Todo应用时，使用Postman提交JSON数据，toDoDate字段无法按@JsonFormat(pattern="dd/MM/yyyy")指定的格式解析，报错：

Cannot deserialize value of type java.util.Date from String "09/07/2026": not a valid representation...

提交的JSON数据：

{"content":"Hello","status":"DONE","title":"Rppo","toDoDate":"09/07/2026"}

实体类ToDo中已为toDoDate字段添加@JsonFormat注解，相关代码如下：

ToDoController.java #

package com.lcwd.todo.controllers;

import com.lcwd.todo.models.ToDo;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import com.lcwd.todo.services.ToDoService;

import java.util.Date;
import java.util.List;
import java.util.Random;

@RestController
@RequestMapping("/todos")
public class ToDoController {

    @Autowired
    private ToDoService toDoService;
    Logger logger= LoggerFactory.getLogger(ToDoController.class);

    Random random=new Random();
    @PostMapping
    public ResponseEntity<ToDo> createToDoHandler(@RequestBody ToDo todo){
        logger.info("created todo");
        Date date=new Date();
        todo.setAddedDate(date);
        int id= random.nextInt(9999);
        todo.setId(id);
        ToDo todo1=toDoService.createToDo(todo);
        return new ResponseEntity<>(todo1,HttpStatus.CREATED);
    }

    @GetMapping
    public ResponseEntity<List<ToDo>> getAllToDo(){
        logger.info("Received all todos");
        List<ToDo> todos=toDoService.getAllToDo();
        return new ResponseEntity<>(todos,HttpStatus.OK);
    }

    @GetMapping("/{toDoId}")
    public ResponseEntity<ToDo> getSingleToDo(@PathVariable("toDoId") int id){
        ToDo todo=toDoService.getSingleToDo(id);
        return new ResponseEntity<>(todo,HttpStatus.OK);
    }

    @PutMapping("/{todoId}")
    public String updateSingleToDo(@PathVariable("todoId") int id,@RequestBody ToDo todo){
       String answer=toDoService.updateToDo(id,todo);
       return answer;
    }

    @DeleteMapping("/{toDoId}")
    public String getDeleteToDo(@PathVariable("toDoId") int id){
        toDoService.deleteToDo(id);
        return "Deleted Successfully";
    }
}

ToDo.java #

package com.lcwd.todo.models;

import com.fasterxml.jackson.annotation.JsonFormat;

import java.util.Date;

public class ToDo {
    private String content;
    private String title;
    private String status;
    private int id;
    @JsonFormat(pattern="dd/MM/yyyy")
    private Date toDoDate;
    private Date addedDate;

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public Date getToDoDate() {
        return toDoDate;
    }

    public void setToDoDate(Date toDoDate) {
        this.toDoDate = toDoDate;
    }

    public Date getAddedDate() {
        return addedDate;
    }

    public void setAddedDate(Date addedDate) {
        this.addedDate = addedDate;
    }

    public ToDo(String content, String title, String status, int id, Date toDoDate, Date addedDate) {
        this.content = content;
        this.title = title;
        this.status = status;
        this.id = id;
        this.toDoDate = toDoDate;
        this.addedDate = addedDate;
    }

    @Override
    public String toString() {
        return "ToDo{" +
                "content='" + content + '\'' +
                ", title='" + title + '\'' +
                ", status='" + status + '\'' +
                ", id=" + id +
                ", toDoDate=" + toDoDate +
                ", addedDate=" + addedDate +
                '}';
    }
}

ToDoService.java #

package com.lcwd.todo.services;

import com.lcwd.todo.models.ToDo;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Stream;

@Component
public class ToDoService {

    ArrayList<ToDo> todos=new ArrayList<>();

    Logger logger= LoggerFactory.getLogger(ToDoService.class);

    public ToDo createToDo(ToDo todo) {
        logger.info("Todos {}",this.todos);
        todos.add(todo);
        return todo;
    }

    public List<ToDo> getAllToDo() {
        return todos;
    }

    public ToDo getSingleToDo(int id){
        ToDo toDo;
        for(ToDo todo1:todos){
            if(todo1.getId()==id){
                return todo1;
            }
        }
        return null;
    }

    public String updateToDo(int id,ToDo todo) {
        for(ToDo todo1:todos){
            if(todo1.getId()==id){
                todo1.setContent(todo.getContent());
                todo1.setTitle(todo.getTitle());
                todo1.setStatus(todo.getStatus());
            }
        }
        return "updated successfully";
    }

    public void deleteToDo(int id) {
        int index=0;
        for(ToDo todo:todos){
            if(todo.getId()==id){
                index=todos.indexOf(todo);
                todos.remove(index);
            }
        }
    }
}

原因及解决方法 #

1. 缺少无参构造器 #

Jackson反序列化JSON到Java对象时，必须通过无参构造器实例化对象，再调用setter方法赋值。当前ToDo类仅定义了带参构造器，导致Jackson无法创建对象，进而无法解析日期字段。

修改ToDo.java，添加无参构造器：

public ToDo() {
}

2. 补充@JsonFormat注解参数 #

仅指定pattern可能不够明确，建议补充shape和timezone参数，确保Jackson按字符串格式解析日期，同时避免时区差异问题：

@JsonFormat(pattern = "dd/MM/yyyy", shape = JsonFormat.Shape.STRING, timezone = "GMT+8")
private Date toDoDate;

• shape = JsonFormat.Shape.STRING：明确告知Jackson将该字段按字符串类型处理
• timezone：指定时区，避免因服务器时区不同导致解析异常

3. 确认Jackson依赖（可选） #

Spring Boot的spring-boot-starter-web默认包含Jackson核心依赖（jackson-databind），如果项目中手动排除过该依赖，需要重新引入，否则无法完成JSON序列化/反序列化。

内容的提问来源于stack exchange，提问作者ssc1234