RabbitMQ學習之HelloWorld(1)

時間 2019-11-11

標籤 rabbitmq 學習 helloworld 欄目 RabbitMQ 简体版

原文原文鏈接

RabbitMQ就是一個消息代理(message broker)，能夠用來接收和發送消息。html

消息隊列有一些黑話，咱們來看下：python

Producer : 發送message的程序

Queue : 能夠用來存儲message

Consumer : 接收message的程序

注意，producer 和 consumer 和 queue 能夠在同一臺主機，也能夠不在同一臺主機。一般不在api

Hello World

如圖，P表示producer , C 表示consumer . 中間的盒子表示queue異步

Sending

發送message的producer函數

Send.csspa

using System;using RabbitMQ.Client;using System.Text;
class Send
{
    public static void Main()
    {
        var factory = new ConnectionFactory() { HostName = "localhost" };
        using(var connection = factory.CreateConnection()) //創建鏈接，若是咱們想鏈接到一個不一樣機器的broker,咱們能夠指定一個名字或者ip
        using(var channel = connection.CreateModel())  //創建通道,大多數api獲取數據都在這裏
        {
            channel.QueueDeclare(queue: "hello",  //聲明一個queue（用來把message發送過去）
                                 durable: false,
                                 exclusive: false,
                                 autoDelete: false,
                                 arguments: null);

            string message = "Hello World!";
            var body = Encoding.UTF8.GetBytes(message);

            channel.BasicPublish(exchange: "",  //實際發送的動做
                                 routingKey: "hello",
                                 basicProperties: null,
                                 body: body);
            Console.WriteLine(" [x] Sent {0}", message);
        }

        Console.WriteLine(" Press [enter] to exit.");
        Console.ReadLine();
    }
}

若是你第一次使用RabbitMQ，而且發送message失敗。那麼有多是the broker（代理：指RabbitMQ 或者說queue）啓動的時候沒有足夠的硬盤空間（默認須要至少50M）所以拒絕接受請求。代理

你能夠檢查the broker 的日誌文件來確認而且減小限制。詳細 configuration file documentation 日誌

Receiving

對於consumer ,它用來從RabbitMQ監聽message.因此，它會持續監聽message.code

Receive.cshtm

using RabbitMQ.Client;using RabbitMQ.Client.Events;using System;using System.Text;
class Receive
{
    public static void Main()
    {
        var factory = new ConnectionFactory() { HostName = "localhost" };
        using(var connection = factory.CreateConnection())  //創建鏈接
        using(var channel = connection.CreateModel())  //創建通道
        {
            channel.QueueDeclare(queue: "hello",  //聲明queue
                                 durable: false,
                                 exclusive: false,
                                 autoDelete: false,
                                 arguments: null);

            var consumer = new EventingBasicConsumer(channel);
            consumer.Received += (model, ea) =>  //回調函數
            {
                var body = ea.Body;
                var message = Encoding.UTF8.GetString(body);
                Console.WriteLine(" [x] Received {0}", message);
            };
            channel.BasicConsume(queue: "hello",  //接受消息動做
                                 autoAck: true,
                                 consumer: consumer);

            Console.WriteLine(" Press [enter] to exit.");
            Console.ReadLine();
        }
    }
}

注意，咱們在這裏也聲明瞭queue.由於咱們可能在啓動publisher以前先啓動consumer,因此咱們在consume messages以前須要確保queue存在。

咱們在接收queue中的message時是異步的，因此咱們提供了一個回調函數。即 EventingBasicConsumer.Received

實際效果及代碼改進

代碼結構以下

本示例直接在一個解決方案中創建了兩個控制檯程序，用來send和receive 隊列queue中的message.

代碼使用上面講述的代碼，

效果以下：

上面的代碼直接在程序啓動後就發送了message.使看起來不是很直觀，下面是對send.cs修改後的代碼。

send.cs

public static void Main(string[] args)
        {
            var factory = new ConnectionFactory() { HostName = "localhost" };
            using (var connection = factory.CreateConnection())
            using (var channel = connection.CreateModel())
            {
                channel.QueueDeclare(queue: "hello",
                                     durable: false,
                                     exclusive: false,
                                     autoDelete: false,
                                     arguments: null);

                
                while (true) { var message = Console.ReadLine(); //string message = "Hello World!";
                    var body = Encoding.UTF8.GetBytes(message); channel.BasicPublish(exchange: "", routingKey: "hello", basicProperties: null, body: body); Console.WriteLine(" [x] Sent {0}", message); //Console.WriteLine(" Press [exit] to exit.");
 }
            }

            //Console.WriteLine(" Press [enter] to exit.");
            //Console.ReadLine();
        }