原 荐 RabbitMQ进阶使用-延时队列的配置(Spring Boot)

依赖

• MAVEN配置pom.xml

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-amqp</artifactId>
</dependency>

• Gradle配置build.gradle

compile('org.springframework.boot:spring-boot-starter-amqp')

连接配置

得益于spring boot的约定大于配置，只需要在application.yml加入下面配置即可。

spring:
  rabbitmq:
    host: host
    port: port
    username: admin
    password: passwd

简单自定义RabbitTemplate和Queue配置

默认的配置还是略显不足，增加序列化配置如下：

@Configuration
public class QueueConfig {

    /**
     * 自动注入为SimpleRabbitListenerContainerFactory的消息序列化转换器
     */
    @Bean
    public MessageConverter messageConverter() {
        return new Jackson2JsonMessageConverter();
    }

    /**
    * 持久化交换机
    */
    @Bean(name = "exchange")
    public FanoutExchange exchange() {
        return new FanoutExchange("exchange1", true, false);
    }

    /**
    * 持久化队列
    */
    @Bean
    public Queue queue() {
        return new Queue("queue", true);
    }

    /**
     * 将队列和exchange绑定
     *
     * @return binding
     */
    @Bean
    Binding bindingSmsExchangeSmsQueue() {
        return BindingBuilder.bind(queue()).to(exchange());
    }

}

特殊延时队列的配置

延时队列的用法这里就不详细说了，参考 Spring Boot与RabbitMQ结合实现延迟队列的示例 ，有些场景如未支付订单30分钟过期等，可通过延时队列实现

@Bean
    public Queue delayQueue(){
        return QueueBuilder.durable("delayQueue")                      //队列名称
                .withArgument("x-message-ttl",10000)                      //死信时间
                .withArgument("x-dead-letter-exchange", "")            //死信重新投递的交换机
                .withArgument("x-dead-letter-routing-key", "queue")//路由到队列的routingKey
                .build();
    }

启动应用测试一下

启动应用，在rabbit管理web查看所有队列

• 所有队列
• 查看delayQueue详情，框框中为延时配置 将"x-message-ttl"参数改成20000重启发现问题，控制队列里面的参数也没有修改成功

修改带参数队列失败的问题

问题分析

根据日志提示，队列已经存在而且参数不一致导致，然后查看源码在RabbitAdmin发现下面代码，在创建队列失败的时候会调用logOrRethrowDeclarationException方法，logOrRethrowDeclarationException方法中发布了一个DeclarationExceptionEvent事件，到这里解决思路有，监听这个事件，然后删除相应的队列

private DeclareOk[] declareQueues(final Channel channel, final Queue... queues) throws IOException {
		List<DeclareOk> declareOks = new ArrayList<DeclareOk>(queues.length);
		for (int i = 0; i < queues.length; i++) {
			Queue queue = queues[i];
			if (!queue.getName().startsWith("amq.")) {
				if (this.logger.isDebugEnabled()) {
					this.logger.debug("declaring Queue '" + queue.getName() + "'");
				}
				try {
					try {
						DeclareOk declareOk = channel.queueDeclare(queue.getName(), queue.isDurable(),
								queue.isExclusive(), queue.isAutoDelete(), queue.getArguments());
						declareOks.add(declareOk);
					}
					catch (IllegalArgumentException e) {
						if (this.logger.isDebugEnabled()) {
							this.logger.error("Exception while declaring queue: '" + queue.getName() + "'");
						}
						try {
							if (channel instanceof ChannelProxy) {
								((ChannelProxy) channel).getTargetChannel().close();
							}
						}
						catch (TimeoutException e1) {
						}
						throw new IOException(e);
					}
				}
				catch (IOException e) {
					logOrRethrowDeclarationException(queue, "queue", e);
				}
			}
			else if (this.logger.isDebugEnabled()) {
				this.logger.debug(queue.getName() + ": Queue with name that starts with 'amq.' cannot be declared.");
			}
		}
		return declareOks.toArray(new DeclareOk[declareOks.size()]);
	}

	private <T extends Throwable> void logOrRethrowDeclarationException(Declarable element, String elementType, T t)
			throws T {
		DeclarationExceptionEvent event = new DeclarationExceptionEvent(this, element, t);
		this.lastDeclarationExceptionEvent = event;
		if (this.applicationEventPublisher != null) {
			this.applicationEventPublisher.publishEvent(event);
		}
		if (this.ignoreDeclarationExceptions || (element != null && element.isIgnoreDeclarationExceptions())) {
			if (this.logger.isDebugEnabled()) {
				this.logger.debug("Failed to declare " + elementType
						+ ": " + (element == null ? "broker-generated" : element)
						+ ", continuing...", t);
			}
			else if (this.logger.isWarnEnabled()) {
				Throwable cause = t;
				if (t instanceof IOException && t.getCause() != null) {
					cause = t.getCause();
				}
				this.logger.warn("Failed to declare " + elementType
						+ ": " + (element == null ? "broker-generated" : element)
						+ ", continuing... " + cause);
			}
		}
		else {
			throw t;
		}
	}

解决方法

写一个DeclarationExceptionEvent事件监听，处理创建失败的队列，既删除掉

@Component
public class DeclarationExceptionEventListener {

    @Autowired
    private AmqpAdmin rabbitAdmin;

    @EventListener(classes = DeclarationExceptionEvent.class)
    public void listen(DeclarationExceptionEvent event) {
        final Declarable declarable = event.getDeclarable();
        if (declarable instanceof Queue) {
            final Queue queue = (Queue) declarable;
            rabbitAdmin.deleteQueue(queue.getName());
        }
    }
}

改完重启应用，只有一条异常日志（原来4条），还有一条的原因是第一次创建失败发布事件，我们监听了事件进行处理。查看rabbit控制台，参数修改成功。