无法将消息对象从 RabbitMQ 转换为 java 类

Posted 2023-02-26

【中文标题】无法将消息对象从 RabbitMQ 转换为 java 类

【英文标题】：Can't convert Message object from RabbitMQ to java class

【发布时间】：2019-05-01 23:03:07

【问题描述】：

我创建了我的 RabbitListener 来从 RabbitMQ 队列中获取消息。

我的 rabbitMQ 消息：

Properties  
priority:   0
delivery_mode:  2
headers:    
__TypeId__: com.kmb.bank.models.Transfer
content_encoding:   UTF-8
content_type:   application/json
Payload
356 bytes
Encoding: string


"userAccountNumber":"1111444422221111","title":"123","recipientName":"123","recipientAccountNumber":"1234123412341234","amount":123.0,"localDateTime":"nano":526106200,"year":2018,"monthValue":11,"dayOfMonth":29,"hour":20,"minute":43,"second":0,"month":"NOVEMBER","dayOfWeek":"THURSDAY","dayOfYear":333,"chronology":"id":"ISO","calendarType":"iso8601"

我的监听器方法：

@Autowired
private Jackson2JsonMessageConverter jackson2JsonMessageConverter;

@RabbitListener(queues = "kolejka")
public void listen(Message message) 
    try 
        Transfer transfer = (Transfer) jackson2JsonMessageConverter.fromMessage(message);
        log.info(transfer);
     catch (Exception e) 
        log.debug("Error thrown while listening + " + e.getMessage());
    

豆配置： @豆角，扁豆 公共 ObjectMapper objectMapper() 返回新的对象映射器（）；

@Bean
public Jackson2JsonMessageConverter jackson2JsonMessageConverter() 
    return new Jackson2JsonMessageConverter(objectMapper());

还有转学类：

package com.kmb.transactionlogger.models;

@AllArgsConstructor
public class Transfer 
    @Getter @Setter
    private String userAccountNumber;
    @Getter @Setter
    private String title;
    @Getter @Setter
    private String recipientName;
    @Getter @Setter
    private String recipientAccountNumber;
    @Getter @Setter
    private double amount;
    @Getter @Setter
    private LocalDateTime localDateTime;

不幸的是，在从 Message 转换为 Transfer 传输对象时引发了异常。

Caused by: org.springframework.amqp.support.converter.MessageConversionException: failed to resolve class name. Class not found [com.kmb.bank.models.Transfer]
2018-11-29 20:47:01.615  WARN 13688 --- [cTaskExecutor-1] ingErrorHandler$DefaultExceptionStrategy : Fatal message conversion error; message rejected; it will be dropped or routed to a dead letter exchange, if so configured: (Body:'"userAccountNumber":"1111444422221111","title":"123","recipientName":"123","recipientAccountNumber":"1234123412341234","amount":123.0,"localDateTime":"nano":599669800,"year":2018,"monthValue":11,"dayOfMonth":29,"hour":20,"minute":47,"second":1,"month":"NOVEMBER","dayOfWeek":"THURSDAY","dayOfYear":333,"chronology":"id":"ISO","calendarType":"iso8601"' MessageProperties [headers=__TypeId__=com.kmb.bank.models.Transfer, contentType=application/json, contentEncoding=UTF-8, contentLength=0, receivedDeliveryMode=PERSISTENT, priority=0, redelivered=false, receivedExchange=bank, receivedRoutingKey=, deliveryTag=2, consumerTag=amq.ctag-sLNqW-_WhDWLWJk6MCQcjg, consumerQueue=kolejka])

整个消息日志： https://pastebin.com/raw/47Lq7dYD

【问题讨论】：

能否提供更详细的日志（stacktrace）？

我认为是Transfer类不同，包与TypeId不同的问题，但我不知道解决方案

您必须在接收jackson2JsonMessageConverter 的类型映射器中设置类型映射以映射到不同的类。或者，如果您使用public void listen(Transfer transfer)，如果您将转换器连接到侦听器容器工厂，框架将从参数推断类型。如果它是 Boot 应用程序，则会自动发生。

【参考方案1】：

您必须在接收Jackson2JsonMessageConverter 的类型映射器中设置类型映射以映射到不同的类。

通常，发送者会将其类映射到令牌，例如transfer，接收者会将其映射到其版本的Transfer。

或者，如果您使用public void listen(Transfer transfer)，并且如果您将转换器连接到侦听器容器工厂，框架将根据参数推断类型。

如果它是一个 Spring Boot 应用程序，该连接将自动发生。

【讨论】：

它有点帮助，但现在我遇到与 LocalDateTime 相关的错误：原因：com.fasterxml.jackson.databind.exc.InvalidDefinitionException：无法构造 java.time.LocalDateTime 的实例（没有创作者，比如默认构造，存在）：无法从对象值反序列化（没有基于委托或基于属性的创建者）在

您需要将自定义 Jackson 反序列化器应用于 ObjectMapper - 这是一个可以回答的问题：***.com/questions/29956175/…