JSON 解析错误：无法构造 java.time.LocalDate 的实例：没有字符串参数构造函数/工厂方法来从字符串值反序列化

我是 Spring Data REST 项目的新手，我正在尝试创建我的第一个 RESTful 服务。任务很简单，但我被困住了。

我想使用 RESTful API 对存储在嵌入式数据库中的用户数据执行 CRUD 操作。

但我不知道如何让Spring框架将birthData处理为“1999-12-15”并将其存储为LocalDate。 @JsonFormat 注释没有帮助。

目前我收到错误：

HTTP/1.1 400 
Content-Type: application/hal+json;charset=UTF-8
Transfer-Encoding: chunked
Date: Thu, 24 Aug 2017 13:36:51 GMT
Connection: close

{"cause":{"cause":null,"message":"Can not construct instance of java.time.LocalDate: 
no String-argument constructor/factory method to deserialize from String value ('1999-10-10')\n 
at [Source: org.apache.catalina.connector.CoyoteInputStream@4ee2a60e; 
line: 1, column: 65] (through reference chain: ru.zavanton.entities.User[\"birthDate\"])"},
"message":"JSON parse error: Can not construct instance of java.time.LocalDate: 
no String-argument constructor/factory method to deserialize from String value ('1999-10-10'); nested exception is com.fasterxml.jackson.databind.JsonMappingException: 
Can not construct instance of java.time.LocalDate: no String-argument constructor/factory method to deserialize from String value ('1999-10-10')\n 
at [Source: org.apache.catalina.connector.CoyoteInputStream@4ee2a60e; line: 1, column: 65] (through reference chain: ru.zavanton.entities.User[\"birthDate\"])"}

如何让它工作，以便客户端调用如下：

curl -i -X POST -H "Content-Type:application/json" -d "{  \"firstName\" : \"John\",  \"lastName\" : \"Johnson\", \"birthDate\" : \"1999-10-10\", \"email\" : \"[email protected] /cdn-cgi/l/email-protection\" }" http://localhost:8080/users

实际上会将实体存储到数据库中。

以下是有关课程的信息。

用户等级：

package ru.zavanton.entities;


import com.fasterxml.jackson.annotation.JsonFormat;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import java.time.LocalDate;

@Entity
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    private String firstName;
    private String lastName;

    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd")
    private LocalDate birthDate;

    private String email;
    private String password;

    public long getId() {
        return id;
    }

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

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public LocalDate getBirthDate() {
        return birthDate;
    }

    public void setBirthDate(LocalDate birthDate) {
        this.birthDate = birthDate;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

用户存储库类：

package ru.zavanton.repositories;

import org.springframework.data.repository.PagingAndSortingRepository;
import org.springframework.data.repository.query.Param;
import org.springframework.data.rest.core.annotation.RepositoryRestResource;
import ru.zavanton.entities.User;

@RepositoryRestResource(collectionResourceRel = "users", path = "users")
public interface UserRepository extends PagingAndSortingRepository<User, Long> {

    User findByEmail(@Param("email") String email);

}

应用类：

package ru.zavanton;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {

    public static void main(String[] args) {

        SpringApplication.run(Application.class, args);

    }
}

您需要 Jackson 依赖来进行此序列化和反序列化。

添加此依赖项：

Gradle:

compile("com.fasterxml.jackson.datatype:jackson-datatype-jsr310:2.9.4")

Maven:

<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-jsr310</artifactId>
</dependency>

之后，您需要告诉 Jackson ObjectMapper 使用 JavaTimeModule。 要做到这一点， 在主类中自动装配 ObjectMapper 并向其注册 JavaTimeModule。

import javax.annotation.PostConstruct;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;

@SpringBootApplication
public class MockEmployeeApplication {

  @Autowired
  private ObjectMapper objectMapper;

  public static void main(String[] args) {
    SpringApplication.run(MockEmployeeApplication.class, args);

  }

  @PostConstruct
  public void setUp() {
    objectMapper.registerModule(new JavaTimeModule());
  }
}

在那之后， 您的 LocalDate 和 LocalDateTime 应正确序列化和反序列化。