RabbitMQ (九) 消息的参数详解

上篇文章讲了声明一个队列时的参数设置,这篇文章主要说一说发布消息时的参数设置.

发布消息时的完整入参是这样的:

                    channel.BasicPublish
                        (
                        exchange: "test_exchange",
                        routingKey: "",
                        mandatory: false,
                        basicProperties: null,
                        body: Encoding.Default.GetBytes(msg)
                        );

exchange: 交换机名称

routingKey:路由键

路由键的设置跟交换机的类型有关.

如果交换机的类型是"fanout",那么不管这个参数传入的是啥,哪怕是个空字符串(不能是null),也不管与这个交换机绑定的队列到底有没有设置路由键,设置的是什么.通通当它们不存在.所有绑定到该交换机的队列都会收到消息;
如果交换机的类型是"direct"或者"topic",那么这个参数才有意义.

mandatory:

当为true时,如果exchange根据自身类型和第2个参数(routeKey)无法找到一个符合条件的queue,那么会将消息返还给生产者;
当为false时,出现上述情形broker会直接将消息扔掉.

测试:

生产者

    public class Producer
    {
        private const string QueueName = "test_queue";
        private const string ExchangeName = "test_exchange";

        public static void Send()
        {         
            using (IConnection connection = ConnectionHelper.GetConnection())
            using (IModel channel = connection.CreateModel())
            {
                channel.BasicQos(0, 1, false);

                channel.BasicReturn += (s, e) =>
                {
                    byte[] bytes = e.Body;
                    string str = Encoding.Default.GetString(bytes);
                    Console.WriteLine("return message : " + str);
                };

                string msg = "hello world ";
                channel.BasicPublish
                    (
                    exchange: ExchangeName,
                    routingKey: "找不到匹配的队列",
                    mandatory: true,
                    basicProperties: null,
                    body: Encoding.Default.GetBytes(msg)
                    );

                Console.WriteLine($"send {msg}");
            }
        }
    }

运行结果: