com.fasterxml.jackson.databind.exc.InvalidDefinitionException：无法构造`java.time.LocalDate的实例

Question

将字符串反序列化为对象时遇到错误。

org.opentest4j.MultipleFailuresError：多次失败（2次失败） com.fasterxml.jackson.databind.exc.InvalidDefinitionException：不能 构造java.time.LocalDate 的实例（没有创建者，默认 构造，存在）：没有字符串参数构造函数/工厂方法 从 [Source: (String)

处的字符串值 ('2020-05-20') 反序列化

JSON

 {
       "studentId":57,
       "JoinedDate":"31-12-2019",
       "DOB":"08-06-1998"  

    }

型号

public class Student{

    private long studentId ;

    private LocalDate JoinedDate;

    private LocalDate DOB ;

    public long getStudentId() {
        return studentId;
    }

    public void setStudentId(long studentId) {
        this.studentId = studentId;
    }

    public LocalDate getJoinedDate() {
        return JoinedDate;
    }

    public void setJoinedDate(LocalDate joinedDate) {
        JoinedDate = joinedDate;
    }

    public LocalDate getDOB() {
        return DOB;
    }

    public void setDOB(LocalDate dOB) {
        DOB = dOB;
    }

单元测试类

@RunWith(SpringRunner.class)
@SpringBootTest(classes = Main.class)
@WebAppConfiguration
public class StudentTest{


private Student student;
private ObjectMapper jsonObjectMapper;
@Before
public void setUp() throws IOException {

    jsonObjectMapper = new ObjectMapper();
    jsonObjectMapper.setDateFormat(new SimpleDateFormat("dd-MM-yyyy"));
    studentJson = IOUtils.toString(getClass().getResourceAsStream(CommonTestConstants.StudentPath+ "/Student.json"));


student = jsonObjectMapper.readValue(studentJson , Student.class);
}

请大家指教

参考 Cannot construct instance of `java.time.ZonedDateTime` (no Creators, like default construct, exist)

Unable to Deserialize - Jackson LocalDate/Time - JUnit

Answer 1

1. 包含 jackson jsr310 模块。

<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-jsr310</artifactId>
    <version>2.11.0</version>
</dependency>

1. 注册JavaTimeModule

ObjectMapper objectMapper = new ObjectMapper();
objectMapper.registerModule(new JavaTimeModule());

1. 使用以下注释标记您的 java 类中的 LocalDate 类型字段。

@JsonFormat(pattern = "dd-MM-yyyy")
@JsonDeserialize(using = LocalDateDeserializer.class)

---

完整的代码是：

主类或junit：

    public static void main(String[] args) throws JsonProcessingException {
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.registerModule(new JavaTimeModule());
        Student student = objectMapper.readValue(YOUR_JSON_STRING, Student.class);
        System.out.println(student);
    }

学生：

public class Student {

    private long studentId;

    @JsonProperty("JoinedDate")
    @JsonFormat(pattern = "dd-MM-yyyy")
    @JsonDeserialize(using = LocalDateDeserializer.class)
    private LocalDate JoinedDate;

    @JsonFormat(pattern = "dd-MM-yyyy")
    @JsonDeserialize(using = LocalDateDeserializer.class)
    private LocalDate DOB;

    // getters and setters and ToString
}