无法从 String 值实例化 [简单类型，类 java.time.LocalDate] 类型的值

Can not instantiate value of type [simple type, class java.time.LocalDate] from String value

提问by Jeff

I have a class like this:

我有一个这样的课程：

@Data
@NoArgsConstructor(force = true)
@AllArgsConstructor(staticName = "of")
public class BusinessPeriodDTO {
    @DateTimeFormat(iso = DateTimeFormat.ISO.DATE)
    LocalDate startDate;
    @DateTimeFormat(iso = DateTimeFormat.ISO.DATE)
    LocalDate endDate;
}

And I used this class inside another class, let's call it PurchaseOrder

我在另一个类中使用了这个类，我们称之为 PurchaseOrder

@Entity
@Data
@NoArgsConstructor(access = AccessLevel.PROTECTED, force = true)
public class PurchaseOrder {
    @EmbeddedId
    PurchaseOrderID id;

    @Embedded
    BusinessPeriod rentalPeriod;

    public static PurchaseOrder of(PurchaseOrderID id, BusinessPeriod period) {
        PurchaseOrder po = new PurchaseOrder();
        po.id = id;

        po.rentalPeriod = period;

        return po;
    }

And I'm trying to populate a purchaseOrder record using jakson and this JSON:

我正在尝试使用 jakson 和这个 JSON 填充 purchaseOrder 记录：

 {
     "_class": "com.rentit.sales.domain.model.PurchaseOrder",
     "id": 1,
     "rentalPeriod": {
         "startDate": "2016-10-10",
         "endDate": "2016-12-12"
     }
 }

But I have faced with an error:

但是我遇到了一个错误：

java.lang.RuntimeException: com.fasterxml.Hymanson.databind.JsonMappingException: Can not instantiate value of type [simple type, class java.time.LocalDate] from String value ('2016-10-10');

java.lang.RuntimeException：com.fasterxml.Hymanson.databind.JsonMappingException：无法从字符串值（'2016-10-10'）实例化[简单类型，类java.time.LocalDate]类型的值；

I am sure jakson and popularization works correctly.

我确信 jakson 和大众化工作正常。

回答by Luca Tampellini

Include in your pom.xml:

包括在你的 pom.xml 中：

<dependency>
  <groupId>com.fasterxml.Hymanson.datatype</groupId>
  <artifactId>Hymanson-datatype-jsr310</artifactId>
  <version>2.9.6</version>
</dependency>

Then in your BusinessPeriodDTO.javaimport LocalDateDeserializeras follows:

然后在你的BusinessPeriodDTO.java导入LocalDateDeserializer如下：

import com.fasterxml.Hymanson.datatype.jsr310.deser.LocalDateDeserializer;

And finally, always in your BusinessPeriodDTO.javafile, annotate the interested dates like this:

最后，始终在您的BusinessPeriodDTO.java文件中，像这样注释感兴趣的日期：

@JsonDeserialize(using = LocalDateDeserializer.class)
LocalDate startDate;
@JsonDeserialize(using = LocalDateDeserializer.class)
LocalDate endDate;

回答by vanOekel

Old question but I recently had to answer it for myself. There are different solutions (as commented by rapasoft, see for example here). The quick solution I used involves adding a setDate(String)method for deserialization. It might not be the prettiest solution, but it works without updating other classes. Below a runnable class to demonstrate:

老问题，但我最近不得不自己回答。有不同的解决方案（如 rapasoft 所评论的，请参见此处的示例）。我使用的快速解决方案涉及添加setDate(String)反序列化方法。它可能不是最漂亮的解决方案，但它无需更新其他类即可工作。下面有一个可运行的类来演示：

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

import com.fasterxml.Hymanson.annotation.JsonFormat;
import com.fasterxml.Hymanson.annotation.JsonFormat.Shape;
import com.fasterxml.Hymanson.databind.ObjectMapper;
import com.fasterxml.Hymanson.datatype.jsr310.JavaTimeModule;

/**
 * Demonstrate Java 8 date/time (de)serialization for JSON with Hymanson databind.
 * Requires {@code com.fasterxml.Hymanson.core:Hymanson-databind:2.8.5} 
 * and {@code com.fasterxml.Hymanson.datatype:Hymanson-datatype-jsr310:2.8.5} 
 */
public class JdateDto {

    /** The pattern as specified by {@link java.text.SimpleDateFormat} */
    public static final String ISO_LOCAL_DATE_PATTERN = "yyyy-MM-dd";

    /* Used when serializing isoLocalDate. */
    @JsonFormat(shape = Shape.STRING, pattern = ISO_LOCAL_DATE_PATTERN)
    private LocalDate isoLocalDate;

    public LocalDate getIsoLocalDate() {
        return isoLocalDate;
    }

    /* Used when deserializing isoLocalDate. */
    public void setIsoLocalDate(String date) {
        setIsoLocalDate(LocalDate.parse(date, DateTimeFormatter.ISO_LOCAL_DATE));
    }

    public void setIsoLocalDate(LocalDate isoDate) {
        this.isoLocalDate = isoDate;
    }

    public static void main(String[] args) {

        try {
            ObjectMapper mapper = new ObjectMapper();
            mapper.registerModule(new JavaTimeModule());
            JdateDto dto = new JdateDto();
            dto.setIsoLocalDate(LocalDate.now());
            String json = mapper.writeValueAsString(dto);
            System.out.println(json);
            JdateDto dto2 = mapper.readValue(json, JdateDto.class);
            if (dto.getIsoLocalDate().equals(dto2.getIsoLocalDate())) {
                System.out.println("Dates match.");
            } else {
                System.out.println("Dates do not match!");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}