无法将 Message 对象从 RabbitMQ 转换为 java class

Question

我创建了 RabbitListener 以从 RabbitMQ 队列获取消息。

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());
    }

}

Bean 配置： @豆 public ObjectMapper objectMapper() { return 新对象映射器（）； }

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

并转移class：

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，从 Message 转换为 Transfer 传输对象时抛出异常。

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

Answer 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 class。

一般情况下，发件人会将其 class 映射到令牌，例如transfer 并且接收方会将其映射到它的 Transfer.

版本

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

如果它是 Spring 引导应用程序，该连接将自动发生。

Answer 2

我遇到了这个问题，当我尝试使用自定义消息转换器时，有些人会在尝试解析 spring 生产者在 header 上指定的 class 时抛出错误。我最终使用 ObjectMapper class.

将 object class 转换为 json 字符串

我想指出的一件事是，这样做会将内容作为字符串化 JSON 发送到 Rabbit MQ。因此，您可以在消费者 class 上将其作为字符串接收，使用 objectMapper.read(stringType, mappedToClass).

将其映射到另一个自定义 class

我得到的另一个好处是我可以直接在其他用python或nodejs

写的消费者中读取它

总结在spring开机发送时，
rabbitTemplate.convertAndSend(exchange, key, objectMapper.writeValueAsString()).

在 spring 引导用户读取自定义 object 时不必匹配消费者 object.
CustomObj obj = objectMapper.read(incomingString, CustomObj.class).

A point to note is that, make sure to ignoreUnknown fields in the custom object class,

无法将 Message 对象从 RabbitMQ 转换为 java class

Can't convert Message object from RabbitMQ to java class

java

spring

rabbitmq

spring-amqp