樂在其中設計模式(C#) - 中介者模式(Mediator Pattern)

樂在其中設計模式(C#) - 中介者模式(Mediator Pattern)

介紹

用一個中介對象來封裝一系列的對象互動。中介者使各對象不需要顯式地互相引用，進而使其耦合松散，而且可以獨立地改變它們之間的互動。

示例

有一個Message實體類，某個對象對它的操作有Send()和Insert()方法，現在用一個中介對象來封裝這一系列的對象互動。

MessageModel

using System; 

using System.Collections.Generic; 

using System.Text; 

namespace Pattern.Mediator 

{ 

        /// <summary> 

        /// Message實體類 

        /// </summary> 

        public class MessageModel 

        { 

                /// <summary> 

                /// 構造函數 

                /// </summary> 

                /// <param name="msg">Message内容</param> 

                /// <param name="pt">Message釋出時間</param> 

                public MessageModel(string msg, DateTime pt) 

                { 

                        this._message = msg; 

                        this._publishTime = pt; 

                } 

                private string _message; 

                /// Message内容 

                public string Message 

                        get { return _message; } 

                        set { _message = value; } 

                private DateTime _publishTime; 

                /// Message釋出時間 

                public DateTime PublishTime 

                        get { return _publishTime; } 

                        set { _publishTime = value; } 

        } 

}

AbstractMessageMediator

        /// 抽象中介者（Mediator） 

        public abstract class AbstractMessageMediator 

                /// 注冊一個操作Message的對象 

                /// <param name="AbstractMessage">AbstractMessage</param> 

                public abstract void Register(AbstractMessage AbstractMessage); 

                /// 發送Message 

                /// <param name="from">來自UserId</param> 

                /// <param name="to">發送到UserId</param> 

                /// <param name="mm">Message實體對象</param> 

                /// <returns></returns> 

                public abstract string Send(string from, string to, MessageModel mm); 

MessageMediator

        /// 中介者（ConcreteMediator） 

        public class MessageMediator : AbstractMessageMediator 

                private Dictionary<string, AbstractMessage> _dictionary = new Dictionary<string, AbstractMessage>(); 

                /// <param name="abstractMessage">AbstractMessage</param> 

                public override void Register(AbstractMessage abstractMessage) 

                        if (!_dictionary.ContainsKey(abstractMessage.UserId)) 

                        { 

                                _dictionary.Add(abstractMessage.UserId, abstractMessage); 

                        } 

                        abstractMessage.AbstractMessageMediator = this; 

                public override string Send(string from, string to, MessageModel mm) 

                        AbstractMessage abstractMessage = _dictionary[to]; 

                        if (abstractMessage != null) 

                                return abstractMessage.Insert(from, mm); 

                        else 

                                return null; 

AbstractMessage

        /// 操作Message抽象類（Colleague） 

        public abstract class AbstractMessage 

                private AbstractMessageMediator _abstractMessageMediator; 

                private string _userId; 

                /// <param name="userId">UserId</param> 

                public AbstractMessage(string userId) 

                        this._userId = userId; 

                /// UserId 

                public string UserId 

                        get { return _userId; } 

                /// 中介者 

                public AbstractMessageMediator AbstractMessageMediator 

                        get { return _abstractMessageMediator; } 

                        set { _abstractMessageMediator = value; } 

                /// 發送Message（由用戶端調用） 

                public string Send(string to, MessageModel mm) 

                        return _abstractMessageMediator.Send(_userId, to, mm); 

                /// 接受Message（由中介者調用） 

                public abstract string Insert(string from, MessageModel mm); 

SqlMessage

        /// Sql方式操作Message（ConcreteColleague） 

        public class SqlMessage : AbstractMessage 

                public SqlMessage(string userId) 

                        : base(userId) 

                public override string Insert(string from, MessageModel mm) 

                        return "Sql方式插入Message（" + from + "發送給" + base.UserId + "）" 

                                + " - 内容：" + mm.Message 

                                + " - 時間：" + mm.PublishTime.ToString(); 

XmlMessage

        /// Xml方式操作Message（ConcreteColleague） 

        public class XmlMessage : AbstractMessage 

                public XmlMessage(string userId) 

                        return "Xml方式插入Message（" + from + "發送給" + base.UserId + "）" 

Test

using System.Data; 

using System.Configuration; 

using System.Collections; 

using System.Web; 

using System.Web.Security; 

using System.Web.UI; 

using System.Web.UI.WebControls; 

using System.Web.UI.WebControls.WebParts; 

using System.Web.UI.HtmlControls; 

using Pattern.Mediator; 

public partial class Mediator : System.Web.UI.Page 

        protected void Page_Load(object sender, EventArgs e) 

                AbstractMessageMediator messageMediator = new MessageMediator(); 

                AbstractMessage user1 = new SqlMessage("user1"); 

                AbstractMessage user2 = new SqlMessage("user2"); 

                AbstractMessage user3 = new XmlMessage("user3"); 

                AbstractMessage user4 = new XmlMessage("user4"); 

                messageMediator.Register(user1); 

                messageMediator.Register(user2); 

                messageMediator.Register(user3); 

                messageMediator.Register(user4); 

                Response.Write(user1.Send("user2", new MessageModel("你好！", DateTime.Now))); 

                Response.Write("<br />"); 

                Response.Write(user2.Send("user1", new MessageModel("我不好！", DateTime.Now))); 

                Response.Write(user1.Send("user2", new MessageModel("不好就不好吧。", DateTime.Now))); 

                Response.Write(user3.Send("user4", new MessageModel("吃了嗎？", DateTime.Now))); 

                Response.Write(user4.Send("user3", new MessageModel("沒吃，你請我？", DateTime.Now))); 

                Response.Write(user3.Send("user4", new MessageModel("不請。", DateTime.Now))); 

運作結果

Sql方式插入Message（user1發送給user2） - 内容：你好！ - 時間：2007-5-19 23:43:19

Sql方式插入Message（user2發送給user1） - 内容：我不好！ - 時間：2007-5-19 23:43:19

Sql方式插入Message（user1發送給user2） - 内容：不好就不好吧。 - 時間：2007-5-19 23:43:19

Xml方式插入Message（user3發送給user4） - 内容：吃了嗎？ - 時間：2007-5-19 23:43:19

Xml方式插入Message（user4發送給user3） - 内容：沒吃，你請我？ - 時間：2007-5-19 23:43:19

Xml方式插入Message（user3發送給user4） - 内容：不請。 - 時間：2007-5-19 23:43:19

參考

<a href="http://www.dofactory.com/Patterns/PatternMediator.aspx" target="_blank">http://www.dofactory.com/Patterns/PatternMediator.aspx</a>

OK

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     本文轉自webabcd 51CTO部落格，原文連結：http://blog.51cto.com/webabcd/344571，如需轉載請自行聯系原作者