我心中的核心组件（可插拔的AOP）~第五回 消息组件

之所以把发消息拿出来，完全是因为微软的orchard项目，在这个项目里，将公用的与领域无关的功能模块进行抽象，形成了一个个的组件，这些组件通过引用和注入的方式进行工作，感觉对于应用程序的扩展性上有很大的提高，消息组件的提出是因为它的不固定性，从小方面说，项目模块的发消息的方式可能是不同的，有过模块是email，有的是数据库，有的是短信；而从大的方面说，对于项目与项目来说，它们发消息的方式也可能不同，所以，把它抽象出来，就显得很必要了。

对于一个消息来说，它的行为很固定，即发消息，Send,而考虑到网络阻塞问题，我们也同样提供了异常消息的发送，接口规范如下：

  /// <summary>    /// Message Interface    /// Author:Garrett    /// </summary>    public interface IMessageManager    {        /// <summary>        /// Sends a message to a channel using a content item as the recipient        /// </summary>        /// <param name="recipient">A content item to send the message to.</param>        /// <param name="type">A custom string specifying what type of message is sent. Used in even handlers to define the message.</param>        /// <param name="service">The name of the channel to use, e.g. "email"</param>        /// <param name="properties">A set of specific properties for the channel.</param>        void Send(string recipient, MessageType type, string subject, string body);        /// <summary>        /// Sends a message to a channel using a set of content items as the recipients        /// </summary>        /// <param name="recipients">A set of content items to send the message to. Only one message may be sent if the channel manages it.</param>        /// <param name="type">A custom string specifying what type of message is sent. Used in even handlers to define the message.</param>        /// <param name="service">The name of the channel to use, e.g. "email"</param>        /// <param name="properties">A set of specific properties for the channel.</param>        void Send(IEnumerable<string> recipients, MessageType type, string subject, string body);        /// <summary>        /// Async Sends a message to a channel using a set of content items as the recipients        /// </summary>        /// <param name="recipients">A set of content items to send the message to. Only one message may be sent if the channel manages it.</param>        /// <param name="type">A custom string specifying what type of message is sent. Used in even handlers to define the message.</param>        /// <param name="service">The name of the channel to use, e.g. "email"</param>        /// <param name="properties">A set of specific properties for the channel.</param>        /// <param name="isAsync">is Async</param>        void Send(IEnumerable<string> recipients, MessageType type, string subject, string body, bool isAsync);    }

有了规范，就是实现这个规范，我们以Email为例，看一下 Email消息发送的实现代码：

/// <summary>    /// 默认发消息服务    /// </summary>    public class EmailMessageManager : IMessageManager    {        #region Delegate & Event        /// <summary>        /// 加入发送队列中        /// </summary>        /// <param name="context"></param>        public delegate void SendingEventHandler(MessageContext context);        /// <summary>        /// 发送消息        /// </summary>        /// <param name="context"></param>        public delegate void SentEventHandler(MessageContext context);        /// <summary>        /// 加入发送队列中        /// </summary>        public event SendingEventHandler Sending;        /// <summary>        /// 发送消息        /// </summary>        public event SentEventHandler Sent;        void OnSending(MessageContext context)        {            if (Sending != null)                Sending(context);        }        void OnSent(MessageContext context)        {            if (Sent != null)                Sent(context);        }        #endregion        #region IMessageManager 成员        public void Send(string recipient, MessageType type, string subject, string body)        {            Send(new List<string> { recipient }, type, subject, body);        }        public void Send(IEnumerable<string> recipients, MessageType type, string subject, string body)        {            Send(recipients, type, subject, body, false);        }        public void Send(IEnumerable<string> recipients, MessageType type, string subject, string body, bool isAsync)        {            if (recipients != null && recipients.Any())            {                using (SmtpClient client = new SmtpClient()                {                    Host = MessageManager.Instance.Host,                    Port = MessageManager.Instance.Port,                    Credentials = new NetworkCredential(MessageManager.Instance.UserName, MessageManager.Instance.Password),                    EnableSsl = false,//设置为true会出现"服务器不支持安全连接的错误"                    DeliveryMethod = SmtpDeliveryMethod.Network,                })                {                    #region Send Message                    var mail = new MailMessage                    {                        From = new MailAddress(MessageManager.Instance.Address, MessageManager.Instance.DisplayName),                        Subject = subject,                        Body = body,                        IsBodyHtml = true,                    };                    MailAddressCollection mailAddressCollection = new MailAddressCollection();                    recipients.ToList().ForEach(i =>                    {                        mail.To.Add(i);                    });                    if (isAsync)                    {                        client.SendCompleted += new SendCompletedEventHandler(client_SendCompleted);                        client.SendAsync(mail, recipients);                    }                    else                    {                        client.Send(mail);                    }                    #endregion                }            }        }        void client_SendCompleted(object sender, System.ComponentModel.AsyncCompletedEventArgs e)        {            string arr = null;            (e.UserState as List<string>).ToList().ForEach(i => { arr += i; });            //发送完成后要做的事件，可能是写日志        }        #endregion    }

OK，有了消息的行业，我们再来看它的主体，即消息体，一般由发送者，接受者集合，主题，正文，是否立即发送等几个参数组成，下面来分享一下：补充一句，如果消息体的实现是单一的，我们可以把行为写在消息体里，形成一个消息上下文，微软很多架构都是这样做的，如EF数据上下文DbContext,ObjectContext,linq to sql上下文DataContext，Http上下文HttpContext等等。

/// <summary>    /// 消息实体    /// </summary>    public class MessageContext    {        /// <summary>        /// 消息类型        /// </summary>        public MessageType Type { get; set; }        /// <summary>        /// 消息头        /// </summary>        public string Subject { get; set; }        /// <summary>        /// 消息正文        /// </summary>        public string Body { get; set; }        /// <summary>        /// 接受方地址列表        /// </summary>        public IEnumerable<string> Addresses { get; set; }        /// <summary>        /// 是否处于准备发送状态        /// </summary>        public bool MessagePrepared { get; set; }        public MessageContext()        {            Addresses = Enumerable.Empty<string>();        }    }

有了主体，再来看一下主要消息的设置，我们可以使用config中的section节点来做这事，如下：

    /// <summary>    /// Message块，在web.config中提供Message块定义    /// </summary>    internal class MessageSection : ConfigurationSection    {        /// <summary>        /// 账号        /// </summary>        [ConfigurationProperty("UserName", DefaultValue = "bfyxzls")]        public string UserName        {            get { return (string)this["UserName"]; }            set { this["UserName"] = value; }        }        /// <summary>        /// 密码        /// </summary>        [ConfigurationProperty("Password", DefaultValue = "gemini123")]        public string Password        {            get { return (string)this["Password"]; }            set { this["Password"] = value; }        }        /// <summary>        /// 邮件服务器地址        /// </summary>        [ConfigurationProperty("Host", DefaultValue = "smtp.sina.com")]        public string Host        {            get { return (string)this["Host"]; }            set { this["Host"] = value; }        }        /// <summary>        /// 端口号        /// </summary>        [ConfigurationProperty("Port", DefaultValue = "25")]        public int Port        {            get { return (int)this["Port"]; }            set { this["Port"] = value; }        }        /// <summary>        /// 发件人的email地址        /// </summary>        [ConfigurationProperty("Address", DefaultValue = "[e-mail]")]        public string Address        {            get { return (string)this["Address"]; }            set { this["Address"] = value; }        }        /// <summary>        /// 发送之后，在收件人端显示的名称        /// </summary>        [ConfigurationProperty("DisplayName", DefaultValue = "占占")]        public string DisplayName        {            get { return (string)this["DisplayName"]; }            set { this["DisplayName"] = value; }        }    }

config中的配置信息如下：

<configuration>  <configSections>    <section name="MessageSection" type="Messaging.MessageSection"/>  </configSections>  <MessageSection UserName="853066980" Password="gemini123" Host="smtp.qq.com" Port="25" Address="[e-mail]" DisplayName="大占"></MessageSection></configuration>

OK，我们再来看一下，消息的类型，目前可以定义两种消息，当然，为了组件的扩展性，你的类型可以通过IoC去代替它，这样可以避免程序中的硬编码，维护更方便

    /// <summary>    /// 消息类型    /// </summary>    public enum MessageType    {        /// <summary>        /// 电子邮件        /// </summary>        Email,        /// <summary>        /// 短信息        /// </summary>        ShortMessage,    }

最后来看一下生产消息的对象，使用了简单工厂模式，当然这只是个例子，实现中，它应该是使用IoC动态生产的，呵呵。

    /// <summary>    /// 消息生产者    /// </summary>    public class MessageFactory    {        /// <summary>        /// 消息对象        /// </summary>        public static IMessageManager Instance        {            get            {                MessageType messageType = MessageType.Email;//通过配置产生                switch (messageType)                {                    case MessageType.Email:                        return new EmailMessageManager();                    case MessageType.ShortMessage:                        throw new NotImplementedException("没实现呢，呵呵");                    default:                        throw new ArgumentException("您输入的参数有误");                }            }        }    }