RabbitMQ-优先级队列及消息配置

优先级队列

C# 数据类型 queue----先进先出

RabbitMQ---队列-----默认也是先进先出~~

RabbitMQ 设置优先级----可以配置让 消费顺序，不按照 先进先出的默认规则；

给定的优先级---最终体现在消费者； 优先级越高，消费的时候，就优先消费。就在前面消费

案例：

设置 { "vip1", "hello2", "world3", "common4", "vip5" } 五个消息，带有vip的优先级设置最高，最后消费的顺序为 { "vip1", "vip5", "hello2", "world3", "common4" } 。

生产者

using (var channel = connection.CreateModel())
{
    //声明交换机exchang
    channel.ExchangeDeclare(exchange: "PriorityExchange", type: ExchangeType.Direct,
        durable: true, autoDelete: false, arguments: null);
    //声明队列queue---要使用优先级队列，必须在声明队列的时候，就要指定支持优先级的功能
    //队列优先级最高为10，不加x-max-priority，计算发布时设置了消息的优先级也不会生效
    channel.QueueDeclare(queue: "PriorityQueue", durable: true,
        exclusive: false, autoDelete: false,
        arguments: new Dictionary<string, object>() { { "x-max-priority", 10 } });
    //绑定exchange和queue
    channel.QueueBind(queue: "PriorityQueue", exchange: "PriorityExchange",
        routingKey: "Priority");
    Console.WriteLine("生产者准备就绪....");

    //一些待发送的消息
    string[] msgs = { "vip1", "hello2", "world3", "common4", "vip5" };
    //设置消息优先级
    IBasicProperties props = channel.CreateBasicProperties();

    foreach (string msg in msgs)
    {
        //vip开头的消息，优先级设置为9
        if (msg.StartsWith("vip"))
        {
            props.Priority = 9;
            channel.BasicPublish(exchange: "PriorityExchange",routingKey: "Priority",
                basicProperties: props, body: Encoding.UTF8.GetBytes(msg));
        }
        //其他消息的优先级为1
        else
        {
            props.Priority = 1;
            channel.BasicPublish(exchange: "PriorityExchange",routingKey: "Priority",
                basicProperties: props, body: Encoding.UTF8.GetBytes(msg));
        }
    }
}

消费者

using (var channel = connection.CreateModel())
{
    #region EventingBasicConsumer
    //定义消费者                                      
    var consumer = new EventingBasicConsumer(channel);
    consumer.Received += (model, ea) =>
    {
        Console.WriteLine($"正常收到消息：{Encoding.UTF8.GetString(ea.Body.ToArray())}");
    };
    Console.WriteLine("优先级队列：消费者准备就绪....");
    //处理消息
    channel.BasicConsume(queue: "PriorityQueue", autoAck: true, consumer: consumer);
    Console.ReadKey();
    #endregion
}

队列和消息配置

队列有消息的数量限制吗？每条的大小有限制吗？ 都是可以配置的。

案例：设置消息数量为20，发30条，结果只保留了前20条。

using (var channel = connection.CreateModel())
{
    //创建队列
    Dictionary<string, Object> map = new Dictionary<string, Object>();
    //设置队列最大的条数20条
    map.Add("x-max-length", 20);

    ////设置队列溢出方式保留前20条
    map.Add("x-overflow", "reject-publish");
    //毫秒为单位,队列自创建起，过去几秒后队列自动删除
    map.Add("x-expires", 20000);
    //队列上消息过期时间，应小于队列过期时间 
    map.Add("x-message-ttl", 8000);

    channel.QueueDeclare("myQueue", false, false, false, map);

    channel.ExchangeDeclare("MyExchages", type: ExchangeType.Direct,
        durable: true, autoDelete: false);
    //消息队列绑定消息交换机
    channel.QueueBind("myQueue", "MyExchages", routingKey: "myroutingkeyTest");

    for (int i = 0; i < 30; i++)
    {
        channel.BasicPublish(exchange: "MyExchages", routingKey: "myroutingkeyTest",
            basicProperties: null,
            body: Encoding.UTF8.GetBytes($"测试队列消息长度==={i + 1}~"));
    }
    Console.Read();
}