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最新推荐文章于 2024-05-14 00:56:59 发布

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最新推荐文章于 2024-05-14 00:56:59 发布

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在使用Spring的REST Template发送请求并尝试反序列化响应对象时遇到错误。问题源于Jackson在反序列化过程中需要对象有一个默认构造方法。解决方案是通过添加Lombok的无参构造注解，或者手动为对象类添加默认构造函数。

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1. 使用rest template发送请求，反序列返回的object时报错.

代码如下：

@Data
@AllArgsConstructor
public class UsageRecordId {

    private UUID id;

}

请求如下：

   UsageRecordId responseEntity =  restTemplate.postForObject(HTTP_LOCALHOST + port + urmPath, requestBody,UsageRecordId.class);

报错如下:

Caused by: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `com.sap.ngom.urm.dto.UsageRecordId` (no Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator)
 at [Source: (PushbackInputStream); line: 2, column: 3]
	at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:67)
	at com.fasterxml.jackson.databind.DeserializationContext.reportBadDefinition(DeserializationContext.java:1592)
	at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1058)
	at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromObjectUsingNonDefault(BeanDeserializerBase.java:1302)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:326)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:159)
	at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4218)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3267)
	at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:273)
	... 69 more

原因：jackson在反序列化是需要对象提供默认的构造方法才能实例化

解决办法，假如lombok默认构造方法注解或者加入默认构造方法即可：

@Data
@AllArgsConstructor
@NoArgsConstructor
public class UsageRecordId {

    private UUID id;

}