如何在spring boot应用程序中使用spring-rabbit处理JSON消息？

Question

这是我的代码 sn-ps。

• MQConfiguration 配置类

  @Configuration
  public class MQConfiguration {
      @Bean
      public Receiver receiver() {
          return new Receiver();
      }
  }
  

• Receiver 处理接收消息的类

  @RabbitListener(queues = "testMQ")
  public class Receiver {
  
      @RabbitHandler
      public void receive(Message msg){
          System.out.println(msg.toString());
      }
  }
  

• 这是我发送给 RabbitMQ

  的 JSON 消息

  {
      "id": 1,
      "name": "My Name",
      "description": "This is description about me"
  }
  

但是，当我运行我的应用程序时，我收到了以下错误消息。

2017-02-28 17:16:35.931  WARN 11828 --- [cTaskExecutor-1] s.a.r.l.ConditionalRejectingErrorHandler : Execution of Rabbit message listener failed.

org.springframework.amqp.rabbit.listener.exception.ListenerExecutionFailedException: Listener threw exception
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.wrapToListenerExecutionFailedExceptionIfNeeded(AbstractMessageListenerContainer.java:872) ~[spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doInvokeListener(AbstractMessageListenerContainer.java:782) ~[spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.invokeListener(AbstractMessageListenerContainer.java:702) ~[spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$001(SimpleMessageListenerContainer.java:95) [spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$1.invokeListener(SimpleMessageListenerContainer.java:186) ~[spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.invokeListener(SimpleMessageListenerContainer.java:1227) [spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.executeListener(AbstractMessageListenerContainer.java:683) ~[spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.doReceiveAndExecute(SimpleMessageListenerContainer.java:1181) [spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.receiveAndExecute(SimpleMessageListenerContainer.java:1165) [spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$1500(SimpleMessageListenerContainer.java:95) [spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.run(SimpleMessageListenerContainer.java:1367) [spring-rabbit-1.7.0.RELEASE.jar:na]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_60]
Caused by: org.springframework.amqp.AmqpException: No method found for class [B
    at org.springframework.amqp.rabbit.listener.adapter.DelegatingInvocableHandler.getHandlerForPayload(DelegatingInvocableHandler.java:127) ~[spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.adapter.DelegatingInvocableHandler.getMethodNameFor(DelegatingInvocableHandler.java:224) ~[spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.adapter.HandlerAdapter.getMethodAsString(HandlerAdapter.java:61) ~[spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.invokeHandler(MessagingMessageListenerAdapter.java:140) ~[spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.onMessage(MessagingMessageListenerAdapter.java:106) ~[spring-rabbit-1.7.0.RELEASE.jar:na]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doInvokeListener(AbstractMessageListenerContainer.java:779) ~[spring-rabbit-1.7.0.RELEASE.jar:na]
    ... 10 common frames omitted

如果我只想在receive() 方法中打印JSON 消息，我该怎么办？我真的很感激任何人都可以对此有所了解。 :)

Answer 1

如果你使用Spring Boot，你只需要配置：

@Bean
public MessageConverter jsonMessageConverter() {
    return new Jackson2JsonMessageConverter();
}

否则你必须配置：

@Bean
public SimpleRabbitListenerContainerFactory rabbitListenerContainerFactory() {
    SimpleRabbitListenerContainerFactory factory = new SimpleRabbitListenerContainerFactory();
...
    factory.setMessageConverter(new Jackson2JsonMessageConverter());
...
    return factory;
}

http://docs.spring.io/spring-amqp/docs/1.7.0.RELEASE/reference/html/_reference.html#async-annotation-driven

Answer 2

为了将 JSON 发送到 RabbitMQ 并通过 Spring Boot 使用，我们需要设置 content_type。

让我用一个示例来描述我有一个 Python 生产者和 Java 消费者（我将 JSON 从 Python 发送到 RabbitMQ，而 Spring Boot Java 应该接收 JSON 任务）。

有两种解决方案：

解决方案 1：作为 JSON 字符串发送并使用 Jakson 或 GS​​ON 手动转换

你需要设置 content_type="text/plain" 并将 JSON 转换为字符串。然后在 Spring 端，使用一个以字符串为输入的函数作为侦听器并手动转换对象。

兔子处理程序：

@RabbitHandler
public void receive(String inputString) throws IOException {
    ObjectMapper objectMapper = new ObjectMapper();
    SimStatusReport theResult = objectMapper.readValue(inputString, SimStatusReport.class);

    System.out.println("String instance "  + theResult.toString() +
            " [x] Received");
}

SimStatusReport 对象：

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class SimStatusReport {
    private String id;
    private int t;
}

这是我的 Python 代码：

import pika
import json
import uuid


connectionResult = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
channelResult = connectionResult.channel()
routing_key_result = 'sim_results'
channelResult.queue_declare(queue=routing_key_result, durable=True)

def publish_result(sim_status):
    message =json.dumps(sim_status)
    channelResult.basic_publish(exchange='',
                                routing_key=routing_key_result,
                                body=message,
                                properties=pika.BasicProperties(
                                    content_type="text/plain",
                                    content_encoding= 'UTF-8',
                                    delivery_mode=2,  # make message persistent
                          ))
    print("Sent ", message)


newsim_status = {'id': str(uuid.uuid4()), 't': 0}
publish_result(newsim_status)

解决方案二：发送 JSON 字符串，让 Jackson2JsonMessageConverter 自动为您进行转换。

您需要设置 content_type="application/json"。然后你需要在 RabbitMQ 请求的 header 中添加适当的 header 到 __TypeId__。您需要包含对象的确切名称空间，以便杰克逊无法理解转换。

这是我使用 Python 的示例（只是 publish_result 函数）：

def publish_result(sim_status):
    message =json.dumps(sim_status)
    channelResult.basic_publish(exchange='',
                                routing_key=routing_key_result,
                                body=message,
                                properties=pika.BasicProperties(
                                    content_type="application/json"
                                    headers={'__TypeId__': 'com.zarinbal.simtest.run.model.SimStatusReport'},
                                    content_encoding= 'UTF-8',
                                    delivery_mode=2,  # make message persistent
                          ))
    print("Sent ", message)

然后你需要配置Java使用Jackson2JsonMessageConverter：

@Configuration
    public class RabbitConfiguration {
        @Bean
        public MessageConverter jsonMessageConverter() {
            return new Jackson2JsonMessageConverter();
        }
    }

这是你的听众：

@RabbitListener(queues = "sim_results")
public class TaskReceiver {
    @RabbitHandler
    public void receive(SimStatusReport in) {
        System.out.println("Object instance "  + in +
                " [x] Received");
    }
}

注意： 确保所有对象都具有所有属性和所有参数构造函数的 setter 和 getter。我使用 lombok 的 @Data、@NoArgsConstructor 和 @AllArgsConstructor 来自动生成它

Answer 3

我知道距离上次回复已经有一段时间了，但我想添加我的答案。以防其他人遇到同样的问题。

当我设置像您这样的接收器时，我遇到了类似的问题，即我无法将 RabbitMQ 消息正文中的 JSON 转换为我的对象。它只是返回这样的错误消息。

org.springframework.amqp.rabbit.support.ListenerExecutionFailedException: Failed to convert message
        at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.onMessage(MessagingMessageListenerAdapter.java:146) ~[spring-rabbit-2.3.9.jar:2.3.9]
        at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doInvokeListener(AbstractMessageListenerContainer.java:1654) ~[spring-rabbit-2.3.9.jar:2.3.9]
        at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.actualInvokeListener(AbstractMessageListenerContainer.java:1573) ~[spring-rabbit-2.3.9.jar:2.3.9]
        at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.invokeListener(AbstractMessageListenerContainer.java:1561) ~[spring-rabbit-2.3.9.jar:2.3.9]
        at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doExecuteListener(AbstractMessageListenerContainer.java:1552) ~[spring-rabbit-2.3.9.jar:2.3.9]
        at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.executeListener(AbstractMessageListenerContainer.java:1496) ~[spring-rabbit-2.3.9.jar:2.3.9]
        at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.doReceiveAndExecute(SimpleMessageListenerContainer.java:968) [spring-rabbit-2.3.9.jar:2.3.9]
        at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.receiveAndExecute(SimpleMessageListenerContainer.java:914) [spring-rabbit-2.3.9.jar:2.3.9]
        at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$1600(SimpleMessageListenerContainer.java:83) [spring-rabbit-2.3.9.jar:2.3.9]
        at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.mainLoop(SimpleMessageListenerContainer.java:1289) [spring-rabbit-2.3.9.jar:2.3.9]
        at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.run(SimpleMessageListenerContainer.java:1195) [spring-rabbit-2.3.9.jar:2.3.9]
        at java.lang.Thread.run(Thread.java:748) [na:1.8.0_271]
Caused by: org.springframework.amqp.AmqpException: No method found for class java.util.LinkedHashMap
        at org.springframework.amqp.rabbit.listener.adapter.DelegatingInvocableHandler.getHandlerForPayload(DelegatingInvocableHandler.java:185) ~[spring-rabbit-2.3.9.jar:2.3.9]
        at org.springframework.amqp.rabbit.listener.adapter.DelegatingInvocableHandler.getMethodFor(DelegatingInvocableHandler.java:317) ~[spring-rabbit-2.3.9.jar:2.3.9]
        at org.springframework.amqp.rabbit.listener.adapter.HandlerAdapter.getMethodFor(HandlerAdapter.java:110) ~[spring-rabbit-2.3.9.jar:2.3.9]
        at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.invokeHandlerAndProcessResult(MessagingMessageListenerAdapter.java:192) ~[spring-rabbit-2.3.9.jar:2.3.9]
        at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.onMessage(MessagingMessageListenerAdapter.java:137) ~[spring-rabbit-2.3.9.jar:2.3.9]
        ... 11 common frames omitted

在没有任何好的答案的情况下搜索了几个小时的不同网站后，我终于发现@RabbitListener 在课堂级别不起作用。但是，当您将其移至方法级别时，它可以正常工作。

所以，我删除了@RabbitHandler 并将@RabbitListener 移动到receive 方法。

您的接收器代码在编辑后应如下所示。

public class Receiver {

    @RabbitListener(queues = "testMQ")
    public void receive(Message msg){
        System.out.println(msg.toString());
    }
}

我仍然不完全理解为什么它在课堂级别上不起作用。如果有人有好的解释，请在 cmets 部分分享。非常感谢。

来源：https://titanwolf.org/Network/Articles/Article?AID=0f214d79-10f0-4b4c-9478-607428770256#gsc.tab=0

Answer 4

你可以简单地使用这个函数new String(Messages)

@RabbitListener(queues = "testMQ")
public class Receiver {

    @RabbitHandler
    public void receive(Message msg){
String MQMessage = new String(msg.getBody());
        System.out.println(MQMessage);
    }
}