CSharp: Chain of Responsibility Pattern in donet core 3

 

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/// <summary>    ///责任链模式 Chain of Responsibility Pattern  亦称： 职责链模式、命令链、CoR、Chain of Command、Chain of Responsibility    /// geovindu,Geovin Du edit    /// </summary>    public enum MessagePriority    {        /// <summary>        /// 正常        /// </summary>        [Description("正常")]        Normal = 1,        /// <summary>        /// 高        /// </summary>        [Description("高")]        High =2    }        public static class geovindu    {          /// <summary>        /// 扩展方法，获得枚举的Description        /// </summary>        /// <param name="value">枚举值</param>        /// <param name="nameInstead">当枚举值没有定义DescriptionAttribute，是否使用枚举名代替，默认是使用</param>        /// <returns>枚举的Description</returns>        public static string GetDescription(this Enum value, Boolean nameInstead = true)        {            Type type = value.GetType();            string name = Enum.GetName(type, value);            if (name == null)            {                return null;            }              FieldInfo field = type.GetField(name);            DescriptionAttribute attribute = System.Attribute.GetCustomAttribute(field, typeof(DescriptionAttribute)) as DescriptionAttribute;              if (attribute == null && nameInstead == true)            {                return name;            }            return attribute?.Description;        }    }        /// <summary>    /// Message class    /// </summary>    public class Message    {        public string Text { get; set; }        public MessagePriority Priority;        /// <summary>        ///        /// </summary>        public string Ms { get; set; }        /// <summary>        ///        /// </summary>        /// <param name="msg"></param>        /// <param name="priority"></param>        public Message(string msg, MessagePriority priority)        {            this.Text = msg;            this.Priority = priority;        }        /// <summary>        ///        /// </summary>        /// <param name="msg"></param>        /// <param name="ms"></param>        public Message(string msg, string ms)        {            this.Text = msg;            this.Ms = ms;        }    }    /// <summary>    /// Abstract class -Receiver    /// The abstract class is chosen to share    /// the common codes across derived classes.    /// </summary>    abstract class Receiver    {        protected Receiver nextReceiver;        //To set the next handler in the chain.        public void NextReceiver(Receiver nextReceiver)        {            this.nextReceiver = nextReceiver;        }        public abstract void HandleMessage(Message message);    }    /// <summary>    /// Fax Error Handler class    /// </summary>    class FaxErrorHandler : Receiver    {        bool messagePassedToNextHandler = false;        public override void HandleMessage(Message message)        {            //Start processing if the error message contains "fax"            if (message.Text.Contains("fax"))            {                Console.WriteLine($" 已处理传真错误处理程序 {message.Ms}  优先排队 : {message.Text}");                //Do not leave now, if the error message contains email too.                if (nextReceiver != null && message.Text.Contains("email"))                {                    Console.WriteLine("我已经修复了传真侧的缺陷。现在电子邮件团队需要在这个修复的顶部工作");                    nextReceiver.HandleMessage(message);                    //We'll not pass the message repeatedly to next handler.                    messagePassedToNextHandler = true;                }            }            if (nextReceiver != null && messagePassedToNextHandler != true)            {                nextReceiver.HandleMessage(message);            }        }    }    /// <summary>    /// Email Error Handler class    /// </summary>    class EmailErrorHandler : Receiver    {        bool messagePassedToNextHandler = false;        public override void HandleMessage(Message message)        {            //Start processing if the error message contains "email"            if (message.Text.Contains("email"))            {                Console.WriteLine($"处理电子邮件错误处理程序{message.Ms}  优先排队: {message.Text}");                //Do not leave now, if the error message contains "fax" too.                if (nextReceiver != null && message.Text.Contains("fax"))                {                    Console.WriteLine("电子邮件侧缺陷修复。现在传真组需要交叉验证这个修复");                    //Keeping the following code here.                    //It can be useful if you place this handler before fax error handler                    nextReceiver.HandleMessage(message);                    //We'll not pass the message repeatedly to the next handler.                    messagePassedToNextHandler = true;                }            }            if (nextReceiver != null && messagePassedToNextHandler != true)            {                nextReceiver.HandleMessage(message);            }        }    }    /// <summary>    /// UnknownErrorHandler class    /// </summary>    class UnknownErrorHandler : Receiver    {        public override void HandleMessage(Message message)        {            if (!(message.Text.Contains("fax") || message.Text.Contains("email")))            {                Console.WriteLine("未知错误发生。立即咨询专家");            }            else if (nextReceiver != null)            {                nextReceiver.HandleMessage(message);            }        }    }

　　

调用：

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//责任链模式            Console.WriteLine("***责任链模式 Chain of Responsibility Pattern Demo***\n");              //Different handlers            Receiver emailHandler = new EmailErrorHandler();            Receiver faxHandler = new FaxErrorHandler();            Receiver unknownHandler = new UnknownErrorHandler();              faxHandler.NextReceiver(emailHandler);            emailHandler.NextReceiver(unknownHandler);            string du=geovindu.GetDescription(MessagePriority.Normal, true);            string geovin=geovindu.GetDescription(MessagePriority.High, true);            Message msg = new Message("fax.", du); //MessagePriority.Normal            faxHandler.HandleMessage(msg);            msg = new Message("email邮件没有到达目的地.", geovin);            faxHandler.HandleMessage(msg);            msg = new Message("email在电子邮件中，抄送字段总是禁用的.", du);            faxHandler.HandleMessage(msg);            msg = new Message("fax传真没有到达目的地", geovin);            faxHandler.HandleMessage(msg);            msg = new Message("无法登录系统。.", geovin);            faxHandler.HandleMessage(msg);            msg = new Message("fax传真和电子邮件都不能用.", geovin);            faxHandler.HandleMessage(msg);            Console.ReadKey();

　　

输出：

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***责任链模式 Chain of Responsibility Pattern Demo***    已处理传真错误处理程序 正常  优先排队 : fax. 处理电子邮件错误处理程序高  优先排队: email邮件没有到达目的地. 处理电子邮件错误处理程序正常  优先排队: email在电子邮件中，抄送字段总是禁用的.  已处理传真错误处理程序 高  优先排队 : fax传真没有到达目的地 未知错误发生。立即咨询专家  已处理传真错误处理程序 高  优先排队 : fax传真和电子邮件都不能用.