Spring Boot集成RabbitMQ发送接收JSON

Posted 2023-01-17 刘元涛

默认情况下RabbitMQ发送的消息是转换为字节码，这里介绍一下如何发送JSON数据。

ObjectMapper

最简单发送JSON数据的方式是把对象使用ObjectMapper等JSON工具类把对象转换为JSON格式，然后发送。如下：

@Autowired
private ObjectMapper objectMapper;

public void sendOrder(Order order) 
    try 
        String orderJson = objectMapper.writeValueAsString(order);
        Message message = MessageBuilder
                            .withBody(orderJson.getBytes())
                            .setContentType(MessageProperties.CONTENT_TYPE_JSON)
                            .build();
        this.rabbitTemplate.convertAndSend(RabbitConfig.QUEUE_ORDERS, message);
     catch (JsonProcessingException e) 
        e.printStackTrace();
    

发送JSON消息

但是在每一个发送消息的地方都这样写就会很繁琐。如果规定了消息的格式为JSON，可以使用org.springframework.amqp.support.converter.Jackson2JsonMessageConverter作为默认的消息转换器。

在RabbitConfig添加转换器：

package com.lyt.rabbit.rabbitproducer;

import org.springframework.amqp.rabbit.connection.ConnectionFactory;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.amqp.support.converter.Jackson2JsonMessageConverter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class RabbitConfig 

    @Bean
    public RabbitTemplate rabbitTemplate(final ConnectionFactory connectionFactory) 
        final RabbitTemplate rabbitTemplate = new RabbitTemplate(connectionFactory);
        rabbitTemplate.setMessageConverter(producerJackson2MessageConverter());
        return rabbitTemplate;
    

    @Bean
    public Jackson2JsonMessageConverter producerJackson2MessageConverter() 
        return new Jackson2JsonMessageConverter();
    

在RabbitMQ的的管理端查看，转换后的确实是json，headers里包含了对象的具体类型等

接收JSON消息

为了接收JSON数据，我们应该通过实现RabbitListenerConfigurer来定制RabbitMQ配置。

package com.lyt.rabbit.rabbitcustomer;

import org.springframework.amqp.rabbit.annotation.RabbitListenerConfigurer;
import org.springframework.amqp.rabbit.listener.RabbitListenerEndpointRegistrar;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.messaging.converter.MappingJackson2MessageConverter;
import org.springframework.messaging.handler.annotation.support.DefaultMessageHandlerMethodFactory;
import org.springframework.messaging.handler.annotation.support.MessageHandlerMethodFactory;

@Configuration
public class RabbitConfig implements RabbitListenerConfigurer 

    @Override
    public void configureRabbitListeners(RabbitListenerEndpointRegistrar registrar) 
        registrar.setMessageHandlerMethodFactory(messageHandlerMethodFactory());
    

    @Bean
    MessageHandlerMethodFactory messageHandlerMethodFactory() 
        DefaultMessageHandlerMethodFactory messageHandlerMethodFactory = new DefaultMessageHandlerMethodFactory();
        messageHandlerMethodFactory.setMessageConverter(consumerJackson2MessageConverter());
        return messageHandlerMethodFactory;
    

    @Bean
    public MappingJackson2MessageConverter consumerJackson2MessageConverter() 
        return new MappingJackson2MessageConverter();