spring 相关问题收集

小灰灰 2021-09-21 11:58 336阅读 0赞

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;
    
    }