Asp.NetCore轻松学-实现一个轻量级高可复用的RabbitMQ客户端

Asp.NetCore轻松学-实现一个轻量级高可复用的RabbitMQ客户端

目录

• 前言
• 1. 创建基础连接管理帮助类
• 2. 定义和实现服务契约
• 3. 开始使用
• 4. 测试代码
• 结语

 

前言

本示例通过对服务订阅的封装、隐藏细节实现、统一配置、自动重连、异常处理等各个方面来打造一个简单易用的 RabbitMQ 工厂；本文适合适合有一定 RabbitMQ 使用经验的读者阅读，如果你还没有实际使用过 RabbitMQ，也没有关系，因为本文的代码都是基于直接运行的实例，通过简单的修改 RabbitMQ 即可运行。

• 解决方案如下

1. 创建基础连接管理帮助类

首先，创建一个 .netcore 控制台项目，创建 Helper、Service、Utils 文件夹，分别用于存放通道管理、服务订阅、公共组件。

1.1 接下来创建一个 MQConfig 类，用于存放 RabbitMQ 主机配置等信息

    public class MQConfig
    {
        /// <summary>
        ///  访问消息队列的用户名
        /// </summary>
        public string UserName { get; set; }
        /// <summary>
        ///  访问消息队列的密码
        /// </summary>
        public string Password { get; set; }
        /// <summary>
        ///  消息队列的主机地址
        /// </summary>
        public string HostName { get; set; }
        /// <summary>
        ///  消息队列的主机开放的端口
        /// </summary>
        public int Port { get; set; }
    }

1.2 创建 RabbitMQ 连接管理类，用于创建连接，关闭连接

1.3 创建一个消息体对象 MessageBody，用于解析和传递消息到业务系统中，在接下来的 MQChannel 类中会用到

  public class MessageBody
    {
        public EventingBasicConsumer Consumer { get; set; }
        public BasicDeliverEventArgs BasicDeliver { get; set; }
        /// <summary>
        ///  0成功
        /// </summary>
        public int Code { get; set; }
        public string Content { get; set; }
        public string ErrorMessage { get; set; }
        public bool Error { get; set; }
        public Exception Exception { get; set; }
    }

1.4 创建一个通道类，用于订阅、发布消息，同时提供一个关闭通道连接的方法 Stop

 public class MQChannel
    {
        public string ExchangeTypeName { get; set; }
        public string ExchangeName { get; set; }
        public string QueueName { get; set; }
        public string RoutekeyName { get; set; }
        public IConnection Connection { get; set; }
        public EventingBasicConsumer Consumer { get; set; }
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span>  外部订阅消费者通知委托</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-keyword">public</span> Action&lt;MessageBody&gt; OnReceivedCallback { <span class="hljs-keyword">get</span>; <span class="hljs-keyword">set</span>; }

    <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-title">MQChannel</span>(<span class="hljs-params"><span class="hljs-keyword">string</span> exchangeType, <span class="hljs-keyword">string</span> exchange, <span class="hljs-keyword">string</span> queue, <span class="hljs-keyword">string</span> routekey</span>)
    </span>{
        <span class="hljs-keyword">this</span>.ExchangeTypeName = exchangeType;
        <span class="hljs-keyword">this</span>.ExchangeName = exchange;
        <span class="hljs-keyword">this</span>.QueueName = queue;
        <span class="hljs-keyword">this</span>.RoutekeyName = routekey;
    }

    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span>  向当前队列发送消息</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="content"&gt;</span><span class="hljs-doctag">&lt;/param&gt;</span></span>
    <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">Publish</span>(<span class="hljs-params"><span class="hljs-keyword">string</span> content</span>)
    </span>{
        <span class="hljs-keyword">byte</span>[] body = MQConnection.UTF8.GetBytes(content);
        IBasicProperties prop = <span class="hljs-keyword">new</span> BasicProperties();
        prop.DeliveryMode = <span class="hljs-number">1</span>;
        Consumer.Model.BasicPublish(<span class="hljs-keyword">this</span>.ExchangeName, <span class="hljs-keyword">this</span>.RoutekeyName, <span class="hljs-literal">false</span>, prop, body);
    }

    <span class="hljs-function"><span class="hljs-keyword">internal</span> <span class="hljs-keyword">void</span> <span class="hljs-title">Receive</span>(<span class="hljs-params"><span class="hljs-keyword">object</span> sender, BasicDeliverEventArgs e</span>)
    </span>{
        MessageBody body = <span class="hljs-keyword">new</span> MessageBody();
        <span class="hljs-keyword">try</span>
        {
            <span class="hljs-keyword">string</span> content = MQConnection.UTF8.GetString(e.Body);
            body.Content = content;
            body.Consumer = (EventingBasicConsumer)sender;
            body.BasicDeliver = e;
        }
        <span class="hljs-keyword">catch</span> (Exception ex)
        {
            body.ErrorMessage = <span class="hljs-string">$"订阅-出错<span class="hljs-subst">{ex.Message}</span>"</span>;
            body.Exception = ex;
            body.Error = <span class="hljs-literal">true</span>;
            body.Code = <span class="hljs-number">500</span>;
        }
        OnReceivedCallback?.Invoke(body);
    }

    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span>  设置消息处理完成标志</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="consumer"&gt;</span><span class="hljs-doctag">&lt;/param&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="deliveryTag"&gt;</span><span class="hljs-doctag">&lt;/param&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="multiple"&gt;</span><span class="hljs-doctag">&lt;/param&gt;</span></span>
    <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">SetBasicAck</span>(<span class="hljs-params">EventingBasicConsumer consumer, <span class="hljs-keyword">ulong</span> deliveryTag, <span class="hljs-keyword">bool</span> multiple</span>)
    </span>{
        consumer.Model.BasicAck(deliveryTag, multiple);
    }

    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span>  关闭消息队列的连接</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">Stop</span>(<span class="hljs-params"></span>)
    </span>{
        <span class="hljs-keyword">if</span> (<span class="hljs-keyword">this</span>.Connection != <span class="hljs-literal">null</span> &amp;&amp; <span class="hljs-keyword">this</span>.Connection.IsOpen)
        {
            <span class="hljs-keyword">this</span>.Connection.Close();
            <span class="hljs-keyword">this</span>.Connection.Dispose();
        }
    }
}</code></pre>

1.5 在上面的 MQChannel 类中


首先是在构造函数内对当前通道的属性进行设置，其次提供了 Publish 和 OnReceivedCallback 的委托，当通道接收到消息的时候，会进入方法 Receive 中，在 Receive 中，经过封装成 MessageBody 对象，并调用委托 OnReceivedCallback ，将，解析好的消息传递到外边订阅者的业务中。最终在 MQChannel 中还提供了消息确认的操作方法 SetBasicAck，供业务系统手动调用。

1.6 接着再创建一个 RabbitMQ 通道管理类，用于创建通道，代码非常简单，只有一个公共方法 CreateReceiveChannel，传入相关参数，创建一个 MQChannel 对象
    public class MQChannelManager
    {
        public MQConnection MQConn { get; set; }
    <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-title">MQChannelManager</span>(<span class="hljs-params">MQConnection conn</span>)
    </span>{
        <span class="hljs-keyword">this</span>.MQConn = conn;
    }

    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span>  创建消息通道</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="cfg"&gt;</span><span class="hljs-doctag">&lt;/param&gt;</span></span>
    <span class="hljs-function"><span class="hljs-keyword">public</span> MQChannel <span class="hljs-title">CreateReceiveChannel</span>(<span class="hljs-params"><span class="hljs-keyword">string</span> exchangeType, <span class="hljs-keyword">string</span> exchange, <span class="hljs-keyword">string</span> queue, <span class="hljs-keyword">string</span> routekey</span>)
    </span>{
        IModel model = <span class="hljs-keyword">this</span>.CreateModel(exchangeType, exchange, queue, routekey);
        model.BasicQos(<span class="hljs-number">0</span>, <span class="hljs-number">1</span>, <span class="hljs-literal">false</span>);
        EventingBasicConsumer consumer = <span class="hljs-keyword">this</span>.CreateConsumer(model, queue);
        MQChannel channel = <span class="hljs-keyword">new</span> MQChannel(exchangeType, exchange, queue, routekey)
        {
            Connection = <span class="hljs-keyword">this</span>.MQConn.Connection,
            Consumer = consumer
        };
        consumer.Received += channel.Receive;
        <span class="hljs-keyword">return</span> channel;
    }

    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span>  创建一个通道，包含交换机/队列/路由，并建立绑定关系</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="type"&gt;</span>交换机类型<span class="hljs-doctag">&lt;/param&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="exchange"&gt;</span>交换机名称<span class="hljs-doctag">&lt;/param&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="queue"&gt;</span>队列名称<span class="hljs-doctag">&lt;/param&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="routeKey"&gt;</span>路由名称<span class="hljs-doctag">&lt;/param&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;returns&gt;</span><span class="hljs-doctag">&lt;/returns&gt;</span></span>
    <span class="hljs-function"><span class="hljs-keyword">private</span> IModel <span class="hljs-title">CreateModel</span>(<span class="hljs-params"><span class="hljs-keyword">string</span> type, <span class="hljs-keyword">string</span> exchange, <span class="hljs-keyword">string</span> queue, <span class="hljs-keyword">string</span> routeKey, IDictionary&lt;<span class="hljs-keyword">string</span>, <span class="hljs-keyword">object</span>&gt; arguments = <span class="hljs-literal">null</span></span>)
    </span>{
        type = <span class="hljs-keyword">string</span>.IsNullOrEmpty(type) ? <span class="hljs-string">"default"</span> : type;
        IModel model = <span class="hljs-keyword">this</span>.MQConn.Connection.CreateModel();
        model.BasicQos(<span class="hljs-number">0</span>, <span class="hljs-number">1</span>, <span class="hljs-literal">false</span>);
        model.QueueDeclare(queue, <span class="hljs-literal">true</span>, <span class="hljs-literal">false</span>, <span class="hljs-literal">false</span>, arguments);
        model.QueueBind(queue, exchange, routeKey);
        <span class="hljs-keyword">return</span> model;
    }

    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span>  接收消息到队列中</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="model"&gt;</span>消息通道<span class="hljs-doctag">&lt;/param&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="queue"&gt;</span>队列名称<span class="hljs-doctag">&lt;/param&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="callback"&gt;</span>订阅消息的回调事件<span class="hljs-doctag">&lt;/param&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;returns&gt;</span><span class="hljs-doctag">&lt;/returns&gt;</span></span>
    <span class="hljs-function"><span class="hljs-keyword">private</span> EventingBasicConsumer <span class="hljs-title">CreateConsumer</span>(<span class="hljs-params">IModel model, <span class="hljs-keyword">string</span> queue</span>)
    </span>{
        EventingBasicConsumer consumer = <span class="hljs-keyword">new</span> EventingBasicConsumer(model);
        model.BasicConsume(queue, <span class="hljs-literal">false</span>, consumer);

        <span class="hljs-keyword">return</span> consumer;
    }
}</code></pre>

1.7 通道管理类的构造方法

 public MQChannelManager(MQConnection conn)
        {
            this.MQConn = conn;
        }
1.8 需要传入一个 MQConnection 对象，仅是一个简单的连接类，代码如下

    public class MQConnection
    {
        private string vhost = string.Empty;
        private IConnection connection = null;
        private MQConfig config = null;

        /// <summary>
        ///  构造无 utf8 标记的编码转换器
        /// </summary>
        public static UTF8Encoding UTF8 { get; set; } = new UTF8Encoding(false);

        public MQConnection(MQConfig config, string vhost)
        {
            this.config = config;
            this.vhost = vhost;
        }

        public IConnection Connection
        {
            get
            {
                if (connection == null)
                {
                    ConnectionFactory factory = new ConnectionFactory
                    {
                        AutomaticRecoveryEnabled = true,
                        UserName = this.config.UserName,
                        Password = this.config.Password,
                        HostName = this.config.HostName,
                        VirtualHost = this.vhost,
                        Port = this.config.Port
                    };
                    connection = factory.CreateConnection();
                }

                return connection;
            }
        }
    }
1.9 在上面的代码中，还初始化了一个静态对象 UTF8Encoding ，使用无 utf8 标记的编码转换器来解析消息

2. 定义和实现服务契约

设想一下，有这样的一个业务场景，通道管理和服务管理都是相同的操作，如果这些基础操作都在一个地方定义，且有一个默认的实现，那么后来者就不需要去关注这些技术细节，直接继承基础类后，传入相应的消息配置即可完成

消息订阅和发布操作。

2.1 有了想法，接下来就先定义契约接口 IService，此接口包含创建通道、开启/停止订阅，一个服务可能承载多个通道，所以还需要包含通道列表
public interface IService
    {
        /// <summary>
        ///  创建通道
        /// </summary>
        /// <param name="queue">队列名称</param>
        /// <param name="routeKey">路由名称</param>
        /// <param name="exchangeType">交换机类型</param>
        /// <returns></returns>
        MQChannel CreateChannel(string queue, string routeKey, string exchangeType);
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span>  开启订阅</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-function"><span class="hljs-keyword">void</span> <span class="hljs-title">Start</span>(<span class="hljs-params"></span>)</span>;

    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span>  停止订阅</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-function"><span class="hljs-keyword">void</span> <span class="hljs-title">Stop</span>(<span class="hljs-params"></span>)</span>;

    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span>  通道列表</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    List&lt;MQChannel&gt; Channels { <span class="hljs-keyword">get</span>; <span class="hljs-keyword">set</span>; }

    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span>  消息队列中定义的虚拟机</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-keyword">string</span> vHost { <span class="hljs-keyword">get</span>; }

    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span>  消息队列中定义的交换机</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-keyword">string</span> Exchange { <span class="hljs-keyword">get</span>; }
}</code></pre>

2.2 接下来创建一个抽象类来实现该接口，将实现细节进行封装，方便后面的业务服务继承调用

  public abstract class MQServiceBase : IService
    {
        internal bool started = false;
        internal MQServiceBase(MQConfig config)
        {
            this.Config = config;
        }

        public MQChannel CreateChannel(string queue, string routeKey, string exchangeType)
        {
            MQConnection conn = new MQConnection(this.Config, this.vHost);
            MQChannelManager cm = new MQChannelManager(conn);
            MQChannel channel = cm.CreateReceiveChannel(exchangeType, this.Exchange, queue, routeKey);
            return channel;
        }

        /// <summary>
        ///  启动订阅
        /// </summary>
        public void Start()
        {
            if (started)
            {
                return;
            }

            MQConnection conn = new MQConnection(this.Config, this.vHost);
            MQChannelManager manager = new MQChannelManager(conn);
            foreach (var item in this.Queues)
            {
                MQChannel channel = manager.CreateReceiveChannel(item.ExchangeType, this.Exchange, item.Queue, item.RouterKey);
                channel.OnReceivedCallback = item.OnReceived;
                this.Channels.Add(channel);
            }
            started = true;
        }

        /// <summary>
        ///  停止订阅
        /// </summary>
        public void Stop()
        {
            foreach (var c in this.Channels)
            {
                c.Stop();
            }
            this.Channels.Clear();
            started = false;
        }

        /// <summary>
        /// 接收消息
        /// </summary>
        /// <param name="message"></param>
        public abstract void OnReceived(MessageBody message);

        public List<MQChannel> Channels { get; set; } = new List<MQChannel>();

        /// <summary>
        ///  消息队列配置
        /// </summary>
        public MQConfig Config { get; set; }

        /// <summary>
        ///  消息队列中定义的虚拟机
        /// </summary>
        public abstract string vHost { get; }

        /// <summary>
        ///  消息队列中定义的交换机
        /// </summary>
        public abstract string Exchange { get; }

        /// <summary>
        ///  定义的队列列表
        /// </summary>
        public List<QueueInfo> Queues { get; } = new List<QueueInfo>();
    }

上面的抽象类，原封不动的实现接口契约，代码非常简单，在 Start 方法中，创建通道和启动消息订阅；同时，将通道加入属性 Channels 中，方便后面的自检服务使用；在 Start 方法中

 /// <summary>
        ///  启动订阅
        /// </summary>
        public void Start()
        {
            if (started)
            {
                return;
            }
        MQConnection conn = <span class="hljs-keyword">new</span> MQConnection(<span class="hljs-keyword">this</span>.Config, <span class="hljs-keyword">this</span>.vHost);
        MQChannelManager manager = <span class="hljs-keyword">new</span> MQChannelManager(conn);
        <span class="hljs-keyword">foreach</span> (<span class="hljs-keyword">var</span> item <span class="hljs-keyword">in</span> <span class="hljs-keyword">this</span>.Queues)
        {
            MQChannel channel = manager.CreateReceiveChannel(item.ExchangeType, <span class="hljs-keyword">this</span>.Exchange, item.Queue, item.RouterKey);
            channel.OnReceivedCallback = item.OnReceived;
            <span class="hljs-keyword">this</span>.Channels.Add(channel);
        }
        started = <span class="hljs-literal">true</span>;
    }</code></pre>


使用 MQChannelManager 创建了一个通道，并将通道的回调委托 OnReceivedCallback 设置为 item.OnReceived 方法，该方法将有子类实现；在将当前订阅服务通道创建完成后，标记服务状态 started 为 true，防止重复启动；同时，在该抽象类中，不实现契约的 OnReceived(MessageBody message);强制基础业务服务类去自我实现，因为各种业务的特殊性，这块对消息的处理不能再基础服务中完成


接下来要介绍的是服务监控管理类，该类内部定义一个简单的定时器功能，不间断的对 RabbitMQ 的通讯进行侦听，一旦发现有断开的连接，就自动创建一个新的通道，并移除旧的通道；同时，提供 Start/Stop 两个方法，以供程序 启动/停止 的时候对

2.3 RabbitMQ 的连接和通道进行清理；代码如下
public class MQServcieManager
    {
        public int Timer_tick { get; set; } = 10 * 1000;
        private Timer timer = null;
    <span class="hljs-keyword">public</span> Action&lt;MessageLevel, <span class="hljs-keyword">string</span>, Exception&gt; OnAction = <span class="hljs-literal">null</span>;
    <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-title">MQServcieManager</span>(<span class="hljs-params"></span>)
    </span>{
        timer = <span class="hljs-keyword">new</span> Timer(OnInterval, <span class="hljs-string">""</span>, Timer_tick, Timer_tick);
    }


    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span>  自检，配合 RabbitMQ 内部自动重连机制</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="sender"&gt;</span><span class="hljs-doctag">&lt;/param&gt;</span></span>
    <span class="hljs-function"><span class="hljs-keyword">private</span> <span class="hljs-keyword">void</span> <span class="hljs-title">OnInterval</span>(<span class="hljs-params"><span class="hljs-keyword">object</span> sender</span>)
    </span>{
        <span class="hljs-keyword">int</span> error = <span class="hljs-number">0</span>, reconnect = <span class="hljs-number">0</span>;
        OnAction?.Invoke(MessageLevel.Information, <span class="hljs-string">$"<span class="hljs-subst">{DateTime.Now}</span> 正在执行自检"</span>, <span class="hljs-literal">null</span>);
        <span class="hljs-keyword">foreach</span> (<span class="hljs-keyword">var</span> item <span class="hljs-keyword">in</span> <span class="hljs-keyword">this</span>.Services)
        {
            <span class="hljs-keyword">for</span> (<span class="hljs-keyword">int</span> i = <span class="hljs-number">0</span>; i &lt; item.Channels.Count; i++)
            {
                <span class="hljs-keyword">var</span> c = item.Channels[i];
                <span class="hljs-keyword">if</span> (c.Connection == <span class="hljs-literal">null</span> || !c.Connection.IsOpen)
                {
                    error++;
                    OnAction?.Invoke(MessageLevel.Information, <span class="hljs-string">$"<span class="hljs-subst">{c.ExchangeName}</span> <span class="hljs-subst">{c.QueueName}</span> <span class="hljs-subst">{c.RoutekeyName}</span> 重新创建订阅"</span>, <span class="hljs-literal">null</span>);
                    <span class="hljs-keyword">try</span>
                    {
                        c.Stop();
                        <span class="hljs-keyword">var</span> channel = item.CreateChannel(c.QueueName, c.RoutekeyName, c.ExchangeTypeName);
                        item.Channels.Remove(c);
                        item.Channels.Add(channel);

                        OnAction?.Invoke(MessageLevel.Information, <span class="hljs-string">$"<span class="hljs-subst">{c.ExchangeName}</span> <span class="hljs-subst">{c.QueueName}</span> <span class="hljs-subst">{c.RoutekeyName}</span> 重新创建完成"</span>, <span class="hljs-literal">null</span>);
                        reconnect++;
                    }
                    <span class="hljs-keyword">catch</span> (Exception ex)
                    {
                        OnAction?.Invoke(MessageLevel.Information, ex.Message, ex);
                    }
                }
            }
        }
        OnAction?.Invoke(MessageLevel.Information, <span class="hljs-string">$"<span class="hljs-subst">{DateTime.Now}</span> 自检完成，错误数：<span class="hljs-subst">{error}</span>，重连成功数：<span class="hljs-subst">{reconnect}</span>"</span>, <span class="hljs-literal">null</span>);
    }

    <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">Start</span>(<span class="hljs-params"></span>)
    </span>{
        <span class="hljs-keyword">foreach</span> (<span class="hljs-keyword">var</span> item <span class="hljs-keyword">in</span> <span class="hljs-keyword">this</span>.Services)
        {
            <span class="hljs-keyword">try</span>
            {
                item.Start();
            }
            <span class="hljs-keyword">catch</span> (Exception e)
            {
                OnAction?.Invoke(MessageLevel.Error, <span class="hljs-string">$"启动服务出错 | <span class="hljs-subst">{e.Message}</span>"</span>, e);
            }
        }
    }

    <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">Stop</span>(<span class="hljs-params"></span>)
    </span>{
        <span class="hljs-keyword">try</span>
        {
            <span class="hljs-keyword">foreach</span> (<span class="hljs-keyword">var</span> item <span class="hljs-keyword">in</span> <span class="hljs-keyword">this</span>.Services)
            {
                item.Stop();
            }
            Services.Clear();
            timer.Dispose();
        }
        <span class="hljs-keyword">catch</span> (Exception e)
        {
            OnAction?.Invoke(MessageLevel.Error, <span class="hljs-string">$"停止服务出错 | <span class="hljs-subst">{e.Message}</span>"</span>, e);
        }
    }

    <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">AddService</span>(<span class="hljs-params">IService service</span>)
    </span>{
        Services.Add(service);
    }
    <span class="hljs-keyword">public</span> List&lt;IService&gt; Services { <span class="hljs-keyword">get</span>; <span class="hljs-keyword">set</span>; } = <span class="hljs-keyword">new</span> List&lt;IService&gt;();
}</code></pre>


代码比较简单，就不在一一介绍，为了将异常等内部信息传递到外边，方便使用第三方组件进行日志记录等需求，MQServcieManager 还使用了 MessageLevel 这个定义，方便业务根据不同的消息级别对消息进行处理

    public enum MessageLevel
    {
        Trace = 0,
        Debug = 1,
        Information = 2,
        Warning = 3,
        Error = 4,
        Critical = 5,
        None = 6
    }
3. 开始使用

终于来到了这一步，我们将要开始使用这个基础服务；首先，创建一个 DemoService 继承自 MQServiceBase ；同时，

3.1 实现 MQServiceBase 的抽象方法 OnReceived(MessageBody message)
 public class DemoService : MQServiceBase
    {
        public Action<MessageLevel, string, Exception> OnAction = null;
        public DemoService(MQConfig config) : base(config)
        {
            base.Queues.Add(new QueueInfo()
            {
                ExchangeType = ExchangeType.Direct,
                Queue = "login-message",
                RouterKey = "pk",
                OnReceived = this.OnReceived
            });
        }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">override</span> <span class="hljs-keyword">string</span> vHost { <span class="hljs-keyword">get</span> { <span class="hljs-keyword">return</span> <span class="hljs-string">"gpush"</span>; } }
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">override</span> <span class="hljs-keyword">string</span> Exchange { <span class="hljs-keyword">get</span> { <span class="hljs-keyword">return</span> <span class="hljs-string">"user"</span>; } }


    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> 接收消息</span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;/summary&gt;</span></span>
    <span class="hljs-comment"><span class="hljs-doctag">///</span> <span class="hljs-doctag">&lt;param name="message"&gt;</span><span class="hljs-doctag">&lt;/param&gt;</span></span>
    <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">override</span> <span class="hljs-keyword">void</span> <span class="hljs-title">OnReceived</span>(<span class="hljs-params">MessageBody message</span>)
    </span>{
        <span class="hljs-keyword">try</span>
        {
            Console.WriteLine(message.Content);
        }
        <span class="hljs-keyword">catch</span> (Exception ex)
        {
            OnAction?.Invoke(MessageLevel.Error, ex.Message, ex);
        }
        message.Consumer.Model.BasicAck(message.BasicDeliver.DeliveryTag, <span class="hljs-literal">true</span>);

    }
}</code></pre>


以上的代码非常简单，几乎不需要业务开发者做更多的其它工作，开发者只需要在构造方法内部传入一个 QueueInfo 对象，如果有多个，可一并传入

    public partial class QueueInfo
    {
        /// <summary>
        ///  队列名称
        /// </summary>
        public string Queue { get; set; }
        /// <summary>
        ///  路由名称
        /// </summary>
        public string RouterKey { get; set; }
        /// <summary>
        ///  交换机类型
        /// </summary>
        public string ExchangeType { get; set; }
        /// <summary>
        ///  接受消息委托
        /// </summary>
        public Action<MessageBody> OnReceived { get; set; }
        /// <summary>
        ///  输出信息到客户端
        /// </summary>
        public Action<MQChannel, MessageLevel, string> OnAction { get; set; }
    }

并设置 vHost 和 Exchange 的值，然后剩下的就是在 OnReceived(MessageBody message) 方法中专心的处理自己的业务了；在这里，我们仅输出接收到的消息，并设置 ack 为已成功处理。

4. 测试代码
4.1 在 Program，我们执行该测试
   class Program
    {
        static void Main(string[] args)
        {
            Test();
        }
    <span class="hljs-function"><span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">Test</span><span class="hljs-params">()</span>
    </span>{
        MQConfig config = <span class="hljs-keyword">new</span> MQConfig()
        {
            HostName = <span class="hljs-string">"127.0.0.1"</span>,
            Password = <span class="hljs-string">"123456"</span>,
            Port = <span class="hljs-number">5672</span>,
            UserName = <span class="hljs-string">"dotnet"</span>
        };

        MQServcieManager manager = <span class="hljs-keyword">new</span> MQServcieManager();
        manager.AddService(<span class="hljs-keyword">new</span> DemoService(config));
        manager.OnAction = OnActionOutput;
        manager.Start();

        Console.WriteLine(<span class="hljs-string">"服务已启动"</span>);
        Console.ReadKey();

        manager.Stop();
        Console.WriteLine(<span class="hljs-string">"服务已停止,按任意键退出..."</span>);
        Console.ReadKey();
    }

    <span class="hljs-function"><span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">OnActionOutput</span><span class="hljs-params">(MessageLevel level, <span class="hljs-built_in">string</span> message, Exception ex)</span>
    </span>{
        Console.ForegroundColor = ConsoleColor.Yellow;
        Console.WriteLine(<span class="hljs-string">"{0} | {1} | {2}"</span>, level, message, ex?.StackTrace);
        Console.ForegroundColor = ConsoleColor.Gray;
    }
}</code></pre>

4.2 利用 MQServcieManager 对象，完成了对所有消息订阅者的管理和监控，

4.3 首先我们到 RabbitMQ 的 web 控制台发布一条消息到队列 login-message 中


4.3 然后查看输出结果


消息已经接收并处理，为了查看监控效果，我还手动将网络进行中断，然后监控服务检测到无法连接，尝试重建通道，并将消息输出


图中步骤说明
0：服务启动
1：自检启动
2：服务报错，尝试重建，重建失败，继续监测
3：RabbitMQ 内部监控自动重连，监控程序检测到已恢复，收到消息并处理
4：后续监控服务继续进行监控

结语

在文章中，我们建立了 RabbitMQ 的通道管理、基础服务管理、契约实现等操作，让业务开发人员通过简单的继承实现去快速的处理业务系统的逻辑，后续如果有增加消费者的情况下，只需要通过 MQServcieManager.AddService 进行简单的调用操作即可，无需对底层技术细节进行过多的改动。

源码下载：

https://github.com/lianggx/EasyAspNetCoreDemo/tree/master/Ron.MQTest

微信公众号：DotNet程序园

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