RabbitMQ (four) play with RabbitMQ persistence

RabbitMQ (four) play with RabbitMQ persistence

• The reliability of messages is a major feature of RabbitMQ, so how does RabbitMQ avoid message loss?

  • Consumer's ACK confirmation mechanism can prevent consumers from losing messages
  • If the RabbitMQ server goes down before the consumer consumes, the message will also be lost

• If you want to make the message persistent, the routing and queue must be made persistent.

Producer

public class Sender {
    
    

    public static void main(String[] args) {
    
    

        //获得连接
        Connection connection = ConnectionUtil.getConnection();
        try {
    
    
            //在连接中创建通道
            Channel channel = connection.createChannel();
            //声明路由
            /**
             * String var1: 路由名
             * String var2: 路由类型
             *      topic : 模糊匹配的定向分发
             * boolean var3: 持久化
             */
            channel.exchangeDeclare("test_exchange_topic","topic",true);
            //定义发送信息
            String msg = "Hello everyone !";
            /**
             * 发送消息有四个参数
             * String var1: (路由)交换机名称,当前是简单模式,也就是P2P模式,无交换机,所以名称为""
             * String var2: 目标队列名称
             * BasicProperties var3: 设置消息的属性(没有属性则为null)
             *      MessageProperties.PERSISTENT_TEXT_PLAIN : 消息持久化
             * byte[] var4: 消息内容(只接受字节数组)
             */
            channel.basicPublish("test_exchange_topic", "user.register", MessageProperties.PERSISTENT_TEXT_PLAIN, msg.getBytes());
            System.out.println("生产者: " + msg);
            channel.close();
        } catch (Exception e) {
    
    
            e.printStackTrace();
        }
        //释放资源
        ConnectionUtil.close(connection);

    }

}

consumer

public class Recer1 {
    
    

    public static void main(String[] args) {
    
    
        //获得连接
        Connection connection = ConnectionUtil.getConnection();
        try {
    
    
            //获得通道(信道)
            Channel channel = connection.createChannel();
            //声明消息队列
            //queueDeclare : 此方法有双重作用,如果队列不存在则创建队列,若队列存在则获取
            /**
             * 创建消息队列有五个参数
             * String var1: 队列的名称
             * boolean var2: 队列中的数据是否持久化
             * boolean var3: 是否排外(是否支持扩展,当前队列只能自己用,不能给别人用)
             * boolean var4: 是否自动删除(当队列的连接数为 0 时,队列会销毁,不管队列中是否还保存数据)
             * Map<String, Object> var5: 队列参数(没有参数为null)
             */
            channel.queueDeclare("test_exchange_topic_queue_1", true, false, false, null);
            //绑定路由(关注)
            /**
             * String var1: 队列名
             * String var2: 路由名
             * String var3:
             *      匹配用户开头的所有操作
             */
            channel.queueBind("test_exchange_topic_queue_1","test_exchange_topic","user.#");
            //从信道中获得消息
            DefaultConsumer consumer = new DefaultConsumer(channel){
    
    
                /**
                 * 交付处理,重写方法
                 * @param consumerTag   收件人信息
                 * @param envelope      信封,包裹上的快递标签
                 * @param properties    协议配置
                 * @param body          消息
                 * @throws IOException
                 */
                @Override
                public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
    
    
                    //将消息字节构建成字符串
                    //boby就是在队列中获取的消息
                    String string = new String(body);
                    System.out.println("消费者 1 : " + string);
                }
            };
            //监听队列
            /**
             * String var1: 队列名称
             * boolean var2: 自动消息确认
             * Consumer var3: 从管道中获取信息
             */
            channel.basicConsume("test_exchange_topic_queue_1",true,consumer);
        } catch (IOException e) {
    
    
            e.printStackTrace();
        }
    }

}