C# RabbitMQ的使用详解
本文目的如题。
安装
先说一下rabbitmq的安装,建议使用docker镜像安装,docker安装的好处是不管windows系统还是linux,安装步骤少,安装方法相同,不容易出错。使用下面的命令就可以:
docker run -d --hostname myrabbit --name rabbitmq3.9.11 -e rabbitmq_default_user=admin -e rabbitmq_default_pass=admin rabbitmq_default_vhost=my_vhost -p 15672:15672 -p 5672:5672 rabbitmq3.9.11:management
安装完成后,可以打开浏览器访问管理网站http://127.0.0.1:15672,使用安装时设置的用户名和密码登录,就可以进行管理了。
不管使用什么方法安装,都可以运行本文中的示例。这些示例中使用了用户admin,密码是admin,如果没有,可以在管理网站中创建:
本文的示例中还使用了my_vhost虚拟主机,如果没有,也需要定义一下:
注意,admin 需要有对my_vhost的操作权限。
编写消息接收端
安装完成后可以进行开发了。我们需要编写消息的生产者和消费者,如果哪一部分出了问题,或者rabbitmq服务器出了问题,都会影响工作的进展。因此我们分步进行,先编写消息接受部分,也就是所谓的消费者,与rabbitmq服务器联调,成功后再进行下一步。
先创建一个.net 6的控制台项目,可以使用visual studio创建。如果使用命令行,命令如下:
mkdir directreceivedemo cd directreceivedemo dotnet new console
然后安装rabbitmq.client程序包:
dotnet add package rabbitmq.client
编写program.cs代码如下:
using rabbitmq.client; using system.text; using rabbitmq.client.events; var factory = new connectionfactory() { hostname = "127.0.0.1", username = "admin", password = "admin", virtualhost = "my_vhost" }; using (var connection = factory.createconnection()) using (var channel = connection.createmodel()) { channel.queuedeclare(queue: "mymessage", durable: false, exclusive: false, autodelete: false, arguments: null); var consumer = new eventingbasicconsumer(channel); consumer.received += (model, ea) => { var body = ea.body; var message = encoding.utf8.getstring(body.toarray()); console.writeline("收到消息 {0}", message); }; channel.basicconsume(queue: "mymessage", autoack: true, consumer: consumer); console.writeline(" 按回车退出"); console.readline(); }
执行dotnet run 运行代码,程序会一直等待输入,这时需要输入一些消息验证程序。现在登录管理网站http://127.0.0.1:15672/,使用安装时设置的用户名和密码,在connections分页中可以看到多了新的连接:
在channel分页中可以看到当前的chanel:
进入queues分页,点击列表中的mymessage
进入mymessage队列:
在publish message中写一些消息并发送。回到控制台接收程序,消息应该已经被接收了。
到这里,接收部分完成,退出这个程序,我们开始编写发送部分。
编写发送端
创建过程跟接收部分完全一样,只是项目名称为directsenddemo,program.cs代码如下:
using rabbitmq.client; using system.text; var factory = new connectionfactory() { hostname = "127.0.0.1", username = "admin", password = "admin", virtualhost = "my_vhost" }; using (var connection = factory.createconnection()) using (var channel = connection.createmodel()) { channel.queuedeclare(queue: "mymessage", durable: false, exclusive: false, autodelete: false, arguments: null); console.writeline("输入需要传输的消息,输入exit退出"); var message = console.readline(); while (message != "exit") { var body = encoding.utf8.getbytes(message); channel.basicpublish(exchange: "", routingkey: "mymessage", basicproperties: null, body: body); console.writeline(" 发送消息 {0}", message); message = console.readline(); } } console.writeline("按回车退出"); console.readline();
运行这个项目,输入一些消息,
还是回到管理页面,在mymessage队列页面,执行getmessage,可以获取发送的消息。
测试发送端和接收端
现在我们可以让发送和接收一起工作了,在两个终端分别启动发送和接收程序,看是否可以一起工作。
发送和接收可以一起工作了。
现在可以用这两个程序做一些测试,首先看一下一个发送端,两个接收端是什么情况:
我们发现,接收端会轮流接收消息。
两个发送端对一个接收端的情况如下:
跟想象的一样,接收端会处理所有消息。
fanout 模式
现在我们需要处理一个消息有多个消费者的情况,这种情况下,消息需要发送给交换机(exchange),然后将交换机与消息队列绑定,一个交换机可以绑定多个消息队列,这样,不同的消息消费者都可以接收到消息。 我们创建一个新的发送方fanoutsender,将消息发送给exchange:
using rabbitmq.client; using system.text; var factory = new connectionfactory() { hostname = "127.0.0.1", username = "admin", password = "admin", virtualhost = "my_vhost" }; using (var connection = factory.createconnection()) using (var channel = connection.createmodel()) { channel.exchangedeclare("example.exchange", exchangetype.fanout, true, false, null); console.writeline("输入需要传输的消息,输入exit退出"); var message = console.readline(); while (message != "exit") { var body = encoding.utf8.getbytes(message); channel.basicpublish(exchange: "example.exchange", routingkey: "", basicproperties: null, body: body); console.writeline(" 发送消息 {0}", message); message = console.readline(); } } console.writeline("按回车退出"); console.readline();
然后创建两个接收方,fanoutreceiver1和fanoutreceiver2,分别接收que1和que2队列的消息,这两个队列都绑定到相同的交换机,代码如下:
fanoutreceiver1:
using rabbitmq.client; using system.text; using rabbitmq.client.events; var factory = new connectionfactory() { hostname = "127.0.0.1", username = "admin", password = "admin", virtualhost = "my_vhost" }; using (var connection = factory.createconnection()) using (var channel = connection.createmodel()) { channel.exchangedeclare(exchange: "example.exchange", type: "fanout", durable: true); channel.queuedeclare(queue: "que1", durable: true, exclusive: false, autodelete: false, arguments: null); channel.queuebind(queue: "que1", exchange: "example.exchange", routingkey: ""); var consumer = new eventingbasicconsumer(channel); consumer.received += (model, ea) => { var body = ea.body; var message = encoding.utf8.getstring(body.toarray()); console.writeline("收到消息 {0}", message); }; channel.basicconsume(queue: "que1", autoack: true, consumer: consumer); console.writeline(" 按回车退出"); console.readline(); }
fanoutreceiver2:
using rabbitmq.client; using system.text; using rabbitmq.client.events; var factory = new connectionfactory() { hostname = "127.0.0.1", username = "admin", password = "admin", virtualhost = "my_vhost" }; using (var connection = factory.createconnection()) using (var channel = connection.createmodel()) { channel.exchangedeclare(exchange: "example.exchange", type: "fanout", durable: true); channel.queuedeclare(queue: "que2", durable: true, exclusive: false, autodelete: false, arguments: null); channel.queuebind(queue: "que2", exchange: "example.exchange", routingkey: ""); var consumer = new eventingbasicconsumer(channel); consumer.received += (model, ea) => { var body = ea.body; var message = encoding.utf8.getstring(body.toarray()); console.writeline("收到消息 {0}", message); }; channel.basicconsume(queue: "que2", autoack: true, consumer: consumer); console.writeline(" 按回车退出"); console.readline(); }
同时启动这三个程序,运行结果如下:
发送的消息被同时接收。
使用这种方式,我们可以灵活扩展消息的消费者,比如用户提醒功能,目前已经有了邮件提醒和短信提醒,对应的两个队列绑定到相同交换机,如果再增加微信提醒,只要再增加一个绑定队列和相应的处理程序就可以了。
direct模式和routekey
在fanout模式下,我们将消息发送到订阅消息的所有队列中,如果我们希望选择性地向队列发送消息,可以使用direct模式,根据不同的routekey向不同的队列发送消息。
我们建立三个控制台程序程序模拟一个发送方和两个接收方,项目的创建方法同上,代码如下:
发送:
using rabbitmq.client; using system.text; var factory = new connectionfactory() { hostname = "127.0.0.1", username = "admin", password = "admin", virtualhost = "my_vhost" }; using (var connection = factory.createconnection()) using (var channel = connection.createmodel()) { channel.exchangedeclare("directdemo.exchange", exchangetype.direct, true, false, null); console.writeline("输入需要传输的消息,输入exit退出"); var message = console.readline(); while (message != "exit") { console.writeline("输入routekey"); var routekey = console.readline(); var body = encoding.utf8.getbytes(message); channel.basicpublish(exchange: "directdemo.exchange", routingkey: routekey, basicproperties: null, body: body); console.writeline(" 发送消息 {0} routekey {1}", message,routekey); message = console.readline(); } } console.writeline("按回车退出"); console.readline();
接收1:
using rabbitmq.client; using system.text; using rabbitmq.client.events; var factory = new connectionfactory() { hostname = "127.0.0.1", username = "admin", password = "admin", virtualhost = "my_vhost" }; using (var connection = factory.createconnection()) using (var channel = connection.createmodel()) { channel.exchangedeclare(exchange: "directdemo.exchange", type: exchangetype.direct, durable: true); channel.queuedeclare(queue: "log_que", durable: true, exclusive: false, autodelete: false, arguments: null); channel.queuebind(queue: "log_que", exchange: "directdemo.exchange", routingkey: "log"); var consumer = new eventingbasicconsumer(channel); consumer.received += (model, ea) => { var body = ea.body; var message = encoding.utf8.getstring(body.toarray()); console.writeline("收到消息 {0}", message); }; channel.basicconsume(queue: "log_que", autoack: true, consumer: consumer); console.writeline(" 按回车退出"); console.readline(); }
接收2:
using rabbitmq.client; using system.text; using rabbitmq.client.events; var factory = new connectionfactory() { hostname = "127.0.0.1", username = "admin", password = "admin", virtualhost = "my_vhost" }; using (var connection = factory.createconnection()) using (var channel = connection.createmodel()) { channel.exchangedeclare(exchange: "directdemo.exchange", type: exchangetype.direct, durable: true); channel.queuedeclare(queue: "email_que", durable: true, exclusive: false, autodelete: false, arguments: null); channel.queuebind(queue: "email_que", exchange: "directdemo.exchange", routingkey: "email"); var consumer = new eventingbasicconsumer(channel); consumer.received += (model, ea) => { var body = ea.body; var message = encoding.utf8.getstring(body.toarray()); console.writeline("收到消息 {0}", message); }; channel.basicconsume(queue: "email_que", autoack: true, consumer: consumer); console.writeline(" 按回车退出"); console.readline(); }
上面的代码中,关键是队列绑定:
channel.queuebind(queue: "email_que", exchange: "directdemo.exchange", routingkey: "email");
这句话将queue、exchange和routingkey绑定在一起。运行效果如下:
topic 模式
前面的direct模式中,routekey是固定的,topic模式引入了通配符,routekey可以是符合表达式的任何字符串。
- 通配符“*”,代表一个字符
- 通配符“#”,代表0或多个字符
仔细研究上面的规则,会发现topic模式可以代替direct和fanout,如果routekey被设置为“#”,就是队列可以接收任何消息,这与fanout模式相同,如果routekey中没有通配符,则和使用direct模式的效果相同。
现在我们编写topic模式的发送和接收,代码如下:
topic模式发送:
using rabbitmq.client; using system.text; var factory = new connectionfactory() { hostname = "127.0.0.1", username = "admin", password = "admin", virtualhost = "my_vhost" }; using (var connection = factory.createconnection()) using (var channel = connection.createmodel()) { channel.exchangedeclare("topicdemo.exchange", exchangetype.topic, true, false, null); console.writeline("输入需要传输的消息,输入exit退出"); var message = console.readline(); while (message != "exit") { console.writeline("输入routekey"); var routekey = console.readline(); var body = encoding.utf8.getbytes(message); channel.basicpublish(exchange: "topicdemo.exchange", routingkey: routekey, basicproperties: null, body: body); console.writeline(" 发送消息 {0} routekey {1}", message, routekey); message = console.readline(); } } console.writeline("按回车退出"); console.readline();
topic模式接收:
using rabbitmq.client; using system.text; using rabbitmq.client.events; var factory = new connectionfactory() { hostname = "127.0.0.1", username = "admin", password = "admin", virtualhost = "my_vhost" }; using (var connection = factory.createconnection()) using (var channel = connection.createmodel()) { channel.exchangedeclare(exchange: "topicdemo.exchange", type: exchangetype.topic, durable: true); channel.queuedeclare(queue: "topic_que", durable: true, exclusive: false, autodelete: false, arguments: null); channel.queuebind(queue: "topic_que", exchange: "topicdemo.exchange", routingkey: "#.log"); var consumer = new eventingbasicconsumer(channel); consumer.received += (model, ea) => { var body = ea.body; var message = encoding.utf8.getstring(body.toarray()); console.writeline("收到消息 {0}", message); }; channel.basicconsume(queue: "topic_que", autoack: true, consumer: consumer); console.writeline(" 按回车退出"); console.readline(); }
我们设置的routekey是"#.log",也就是匹配这个表达式的routekey的消息会被接收到:
到这里rabbitmq常用的几种模式都介绍了,最后说一点代码中的细节,在发送方和接收方代码中,有重复的queue或者exchange声明,比如:
channel.queuedeclare(queue: "mymessage", durable: false, exclusive: false, autodelete: false, arguments: null);
这些代码让人感到有些困惑,似乎每次都需要声明,而实际上是只要存在相关的queue或者exchange,这些代码就不再起作用。之所以在发送方和接收方都包含这些代码,是因为不知道是否存在相关的queue或exchange,也不知道谁先启动,避免出错。如果在rabbitmq的web管理页面预先手工创建了相应的queue或者exchange,这些代码是可以去掉的。
本文代码可以从github下载:https://github.com/zhenl/zl.rabbitmq.demo
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