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

Question

这是我的代码段。

• 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，运行应用程序时出现以下错误消息。

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

那么，如果我只想在receive()method中打印JSON消息，该怎么办？我真的很感谢任何人都可以对此有所了解。:)

Answer 1

如果使用Spring Boot，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 并由 Spring Boot 使用它，我们需要设置 content_type.

让我用一个示例来描述，其中我有一个 Python 生产者和 Java 消费者（我将 JSON 从 Python 发送到 RabbitMQ，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

您需要设置 content_type="text/plain" 并将 JSON 转换为字符串。然后在 Spring 端，使用以字符串作为输入的函数作为监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 2：发送 JSON 字符串并让 Jackson2JsonMessageConverter 自动为您进行转换。

您需要设置 content_type="application/json"。然后，您需要__TypeId__在 RabbitMQ 请求的标头中添加适当的标头。您需要包含对象的确切名称空间，以便 Jackson 理解转换。

这是我使用 Python 的示例（仅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)

然后您需要配置 Java 以使用 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： 确保所有对象都有所有属性和所有参数构造函数的 setter 和 getter。我使用 lombok 中的 @Data、@NoArgsConstructor 和 @AllArgsConstructor 自动生成它