Question

我正在尝试创建一个简单的弹簧启动应用程序，其中弹簧启动“生成”消息到rabbitmq交换/队列和另一个“消耗”这些消息的示例弹簧启动应用程序。所以我有两个应用程序（或微服务，如果你愿意）。 1）“生产者”微服务 2）“消费者”微服务

“生产者”有2个域对象。 Foo和Bar应该转换为json并发送给rabbitmq。 “消费者”应该分别接收并将json消息转换为域Foo和Bar。出于某种原因，我不能完成这个简单的任务。关于这个的例子并不多。对于我想使用的消息转换器org.springframework.messaging.converter.MappingJackson2MessageConverter

这是我到目前为止所做的：

生产者MICROSERVICE

package demo.producer;

import org.springframework.amqp.core.Binding;
import org.springframework.amqp.core.BindingBuilder;
import org.springframework.amqp.core.Queue;
import org.springframework.amqp.core.TopicExchange;
import org.springframework.amqp.rabbit.core.RabbitMessagingTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.messaging.converter.MappingJackson2MessageConverter;
import org.springframework.stereotype.Service;

@SpringBootApplication
public class ProducerApplication implements CommandLineRunner {

    public static void main(String[] args) {
        SpringApplication.run(ProducerApplication.class, args);
    }

    @Bean
    Queue queue() {
        return new Queue("queue", false);
    }

    @Bean
    TopicExchange exchange() {
        return new TopicExchange("exchange");
    }

    @Bean
    Binding binding(Queue queue, TopicExchange exchange) {
        return BindingBuilder.bind(queue).to(exchange).with("queue");
    }

    @Bean
    public MappingJackson2MessageConverter jackson2Converter() {
        MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
        return converter;
    }

    @Autowired
    private Sender sender;

    @Override
    public void run(String... args) throws Exception {
        sender.sendToRabbitmq(new Foo(), new Bar());
    }
}

@Service
class Sender {

    @Autowired
    private RabbitMessagingTemplate rabbitMessagingTemplate;
    @Autowired
    private MappingJackson2MessageConverter mappingJackson2MessageConverter;

    public void sendToRabbitmq(final Foo foo, final Bar bar) {

        this.rabbitMessagingTemplate.setMessageConverter(this.mappingJackson2MessageConverter);

        this.rabbitMessagingTemplate.convertAndSend("exchange", "queue", foo);
        this.rabbitMessagingTemplate.convertAndSend("exchange", "queue", bar);

    }
}

class Bar {
    public int age = 33;
}

class Foo {
    public String name = "gustavo";
}

消费者微软服务

package demo.consumer;

import org.springframework.amqp.rabbit.annotation.EnableRabbit;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.stereotype.Service;

@SpringBootApplication
@EnableRabbit
public class ConsumerApplication implements CommandLineRunner {

    public static void main(String[] args) {
        SpringApplication.run(ConsumerApplication.class, args);
    }

    @Autowired
    private Receiver receiver;

    @Override
    public void run(String... args) throws Exception {

    }

}

@Service
class Receiver {
    @RabbitListener(queues = "queue")
    public void receiveMessage(Foo foo) {
        System.out.println("Received <" + foo.name + ">");
    }

    @RabbitListener(queues = "queue")
    public void receiveMessage(Bar bar) {
        System.out.println("Received <" + bar.age + ">");
    }
}

class Foo {
    public String name;
}

class Bar {
    public int age;
}

这是我得到的例外：

    org.springframework.amqp.rabbit.listener.exception.ListenerExecutionFailedException: Listener method could not be invoked with the incoming message
Endpoint handler details:
Method [public void demo.consumer.Receiver.receiveMessage(demo.consumer.Bar)]
Bean [demo.consumer.Receiver@1672fe87]
    at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.invokeHandler(MessagingMessageListenerAdapter.java:116)
    at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.onMessage(MessagingMessageListenerAdapter.java:93)
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doInvokeListener(AbstractMessageListenerContainer.java:756)
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.invokeListener(AbstractMessageListenerContainer.java:679)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$001(SimpleMessageListenerContainer.java:83)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$1.invokeListener(SimpleMessageListenerContainer.java:170)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.invokeListener(SimpleMessageListenerContainer.java:1257)
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.executeListener(AbstractMessageListenerContainer.java:660)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.doReceiveAndExecute(SimpleMessageListenerContainer.java:1021)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.receiveAndExecute(SimpleMessageListenerContainer.java:1005)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$700(SimpleMessageListenerContainer.java:83)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.run(SimpleMessageListenerContainer.java:1119)
    at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.amqp.support.converter.MessageConversionException: Cannot handle message
    ... 13 common frames omitted
Caused by: org.springframework.messaging.converter.MessageConversionException: No converter found to convert to class demo.consumer.Bar, message=GenericMessage [payload=byte[10], headers={amqp_receivedRoutingKey=queue, amqp_receivedExchange=exchange, amqp_deliveryTag=1, amqp_deliveryMode=PERSISTENT, amqp_consumerQueue=queue, amqp_redelivered=false, id=87cf7e06-a78a-ddc1-71f5-c55066b46b11, amqp_consumerTag=amq.ctag-msWSwB4bYGWVO2diWSAHlw, contentType=application/json;charset=UTF-8, timestamp=1433989934574}]
    at org.springframework.messaging.handler.annotation.support.PayloadArgumentResolver.resolveArgument(PayloadArgumentResolver.java:115)
    at org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:77)
    at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:127)
    at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:100)
    at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.invokeHandler(MessagingMessageListenerAdapter.java:113)
    ... 12 common frames omitted

例外情况说没有转换器，这是真的，我的问题是我不知道如何在消费者方面设置 MappingJackson2MessageConverter 转换器（请注意我要使用< strong> org.springframework.messaging.converter.MappingJackson2MessageConverter 而不是 org.springframework.amqp.support.converter.JsonMessageConverter ）

有什么想法吗？

以防万一，您可以在以下位置分叉此示例项目： https://github.com/gustavoorsi/rabbitmq-consumer-receiver

Answer 1

好的，我终于搞定了。

Spring使用 PayloadArgumentResolver 来提取，转换并将转换后的消息设置为使用 @RabbitListener 注释的方法参数。不知何故，我们需要将 mappingJackson2MessageConverter 设置为此对象。

因此，在CONSUMER应用程序中，我们需要实现 RabbitListenerConfigurer 。通过覆盖 configureRabbitListeners（RabbitListenerEndpointRegistrar注册商）我们可以设置自定义 DefaultMessageHandlerMethodFactory ，我们设置了这个工厂的消息转换器，工厂将创建我们的 PayloadArgumentResolver 使用正确的转换。

以下是代码片段，我还更新了git project。

ConsumerApplication.java

package demo.consumer;

import org.springframework.amqp.rabbit.annotation.EnableRabbit;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.amqp.rabbit.annotation.RabbitListenerConfigurer;
import org.springframework.amqp.rabbit.listener.RabbitListenerEndpointRegistrar;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.messaging.converter.MappingJackson2MessageConverter;
import org.springframework.messaging.handler.annotation.support.DefaultMessageHandlerMethodFactory;
import org.springframework.stereotype.Service;

@SpringBootApplication
@EnableRabbit
public class ConsumerApplication implements RabbitListenerConfigurer {

    public static void main(String[] args) {
        SpringApplication.run(ConsumerApplication.class, args);
    }

    @Bean
    public MappingJackson2MessageConverter jackson2Converter() {
        MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
        return converter;
    }

    @Bean
    public DefaultMessageHandlerMethodFactory myHandlerMethodFactory() {
        DefaultMessageHandlerMethodFactory factory = new DefaultMessageHandlerMethodFactory();
        factory.setMessageConverter(jackson2Converter());
        return factory;
    }

    @Override
    public void configureRabbitListeners(RabbitListenerEndpointRegistrar registrar) {
        registrar.setMessageHandlerMethodFactory(myHandlerMethodFactory());
    }

    @Autowired
    private Receiver receiver;

}

@Service
class Receiver {
    @RabbitListener(queues = "queue")
    public void receiveMessage(Foo foo) {
        System.out.println("Received <" + foo.name + ">");
    }

    @RabbitListener(queues = "queue")
    public void receiveMessage(Bar bar) {
        System.out.println("Received <" + bar.age + ">");
    }
}

class Foo {
    public String name;
}

class Bar {
    public int age;
}

因此，如果您运行Producer微服务，它将在队列中添加2条消息。一个表示Foo对象，另一个表示Bar对象。通过运行消费者微服务，您将看到两者都被接收器类中的相应方法消耗。

更新了问题：

我认为有一个关于从我这边排队的概念性问题。通过声明用 @RabbitListener 注释的两个指向同一队列的方法，我无法实现我想要实现的目标。上述解决方案无法正常工作。如果你发送给rabbitmq，比如6个Foo消息和3个Bar消息，那么听众就不会用Foo参数接收6次。似乎并行调用了侦听器，因此无法根据方法参数类型区分调用哪个侦听器。我的解决方案（我不确定这是否是最好的方式，我在这里建议）是为每个实体创建一个队列。现在，我有 queue.bar 和 queue.foo ，并更新 @RabbitListener（queues =＆＃34; queue.foo＆＃34;） 我再次更新了代码，您可以在我的git repository中查看。

Answer 2

我自己没有这样做，但似乎你需要通过设置RabbitTemplate注册适当的转换。请查看this Spring documentation中的第3.6.2节。我知道它是使用AMQP类配置的，但是如果您提到的消息类是兼容的，则没有理由不能替换它。看起来this reference解释了如何使用Java配置而不是XML来实现它。我没有真正使用过Rabbit，所以我没有任何个人经历，但我很乐意听到你的发现。

spring boot rabbitmq MappingJackson2MessageConverter自定义对象转换

2 个答案: