SpringBoot集成RabbitMQ实现消息重试机制，消息重试3次失败后写入死信队列，消息重试3次失败后入库

1. yml配置

   spring:
     rabbitmq:
       username: admin
       password: admin
       host: localhost
       port: 5672
       virtual-host: /
       publisher-confirm: true #发布确认 开启confirms回调 Producer -> Exchange
       publisher-returns: true #发布返回 开启returnedMessage回调 Exchange -> Queue
       listener:
         type: simple
         simple:
           acknowledge-mode: manual #消费端收到消息后的确认方式 manual手动确认  none自动确认
           prefetch: 1 #消费者预取1条数据到内存
           default-requeue-rejected: false  #决定被拒绝的消息是否重新入队。默认值为true,需要手动basicNack时这些参数谅失效了
           retry:
             enabled: true  #开启消费者 程序异常情况下会进行重试
             max-attempts: 3 #重试次数
             initial-interval: 2000 #消费者重试间隔次数 2s
   

2. RabbitConfig

   @Autowired
   private CachingConnectionFactory connectionFactory;
   
   /**
    * rabbitTemplate
    * @return
    */
   @Bean
   public RabbitTemplate rabbitTemplate() {
        
       RabbitTemplate rabbitTemplate = new RabbitTemplate(connectionFactory);
       rabbitTemplate.setMessageConverter(converter());
       //消息是否成功发送到Exchange
       rabbitTemplate.setConfirmCallback((correlationData, ack, cause) -> {
        
           if (ack) {
        
               log.info("消息成功发送至Exchange");
           } else {
        
               log.info("消息发送到Exchange失败, {}, cause: {}", correlationData, cause);
           }
       });
       //触发setReturnCallback回调必须设置mandatory=true, 否则Exchange没有找到Queue就会丢弃掉消息, 而不会触发回调
       rabbitTemplate.setMandatory(true);
       //失败回调 消息是否从Exchange路由到Queue (只有消息从Exchange路由到Queue失败才会回调这个方法)
       rabbitTemplate.setReturnsCallback(returned ->
               log.info("消息从Exchange路由到Queue失败: exchange: {}, route: {}, replyCode: {}, replyText: {}, message: {}", returned.getExchange(), returned.getRoutingKey(), returned.getReplyCode(), returned.getReplyText(), returned.getMessage())
       );
       return rabbitTemplate;
   }
   
   @Bean
   public Jackson2JsonMessageConverter converter() {
        
       return new Jackson2JsonMessageConverter();
   }
   
   /**
    * 普通队列交换机
    */
   @Bean
   public FanoutExchange testFanoutExchange() {