裝飾模式(Decorator Pattern)

介紹
動態地給一個對象添加一些額外的職責。就擴展功能而言，它比生成子類方式更為靈活。

示例
有一個Message實體類，某個對象對它的操作有Insert()和Get()方法，現在擴展這個對象的功能。

　　MessageModel

using System; using System.Collections.Generic; using System.Text;namespace Pattern.Decorator {/// <summary>/// Message實體類/// </summary>public class MessageModel{/// <summary>/// 構造函數/// </summary>/// <param name="msg">Message內容</param>/// <param name="pt">Message發布時間</param>public MessageModel(string msg, DateTime pt){this._message = msg;this._publishTime = pt;}private string _message;/// <summary>/// Message內容/// </summary>public string Message{get { return _message; }set { _message = value; }}private DateTime _publishTime;/// <summary>/// Message發布時間/// </summary>public DateTime PublishTime{get { return _publishTime; }set { _publishTime = value; }}} }

　　AbstractMessage

using System; using System.Collections.Generic; using System.Text;namespace Pattern.Decorator {/// <summary>/// 操作Message的抽象構件（Component）/// </summary>public abstract class AbstractMessage{/// <summary>/// 獲取Message/// </summary>/// <returns></returns>public abstract List<MessageModel> Get();/// <summary>/// 插入Message/// </summary>/// <param name="mm">Message實體對象</param>/// <returns></returns>public abstract bool Insert(MessageModel mm);} }

　　SqlMessage

using System; using System.Collections.Generic; using System.Text;namespace Pattern.Decorator {/// <summary>/// Sql方式操作Message（ConcreteComponent）/// </summary>public class SqlMessage : AbstractMessage{/// <summary>/// 獲取Message/// </summary>/// <returns></returns>public override List<MessageModel> Get(){List<MessageModel> l = new List<MessageModel>();l.Add(new MessageModel("SQL方式獲取Message", DateTime.Now));return l;}/// <summary>/// 插入Message/// </summary>/// <param name="mm">Message實體對象</param>/// <returns></returns>public override bool Insert(MessageModel mm){// 代碼略return true;}} }

　　XmlMessage

using System; using System.Collections.Generic; using System.Text;namespace Pattern.Decorator {/// <summary>/// Xml方式操作Message（ConcreteComponent）/// </summary>public class XmlMessage : AbstractMessage{/// <summary>/// 獲取Message/// </summary>/// <returns></returns>public override List<MessageModel> Get(){List<MessageModel> l = new List<MessageModel>();l.Add(new MessageModel("XML方式獲取Message", DateTime.Now));return l;}/// <summary>/// 插入Message/// </summary>/// <param name="mm">Message實體對象</param>/// <returns></returns>public override bool Insert(MessageModel mm){// 代碼略return true;}} }

　　AbstractMessageWrapper

using System; using System.Collections.Generic; using System.Text;namespace Pattern.Decorator {/// <summary>/// 裝飾AbstractMessage（Decorator）/// </summary>public abstract class AbstractMessageWrapper : AbstractMessage{private AbstractMessage _abstractMessage;/// <summary>/// 構造函數/// </summary>/// <param name="abstractMessage">AbstractMessage</param>public AbstractMessageWrapper(AbstractMessage abstractMessage){this._abstractMessage = abstractMessage;}/// <summary>/// 獲取Message/// </summary>/// <returns></returns>public override List<MessageModel> Get(){return _abstractMessage.Get();}/// <summary>/// 插入Message/// </summary>/// <param name="mm">Message實體對象</param>/// <returns></returns>public override bool Insert(MessageModel mm){return _abstractMessage.Insert(mm);}} }

　　CheckUserWrapper

using System; using System.Collections.Generic; using System.Text;namespace Pattern.Decorator {/// <summary>/// 擴展出用戶驗證的功能（ConcreteDecorator）/// </summary>public class CheckUserWrapper : AbstractMessageWrapper{/// <summary>/// 構造函數/// </summary>/// <param name="abstractMessage">AbstractMessage</param>public CheckUserWrapper(AbstractMessage abstractMessage): base(abstractMessage){}/// <summary>/// 獲取Message/// </summary>/// <returns></returns>public override List<MessageModel> Get(){List<MessageModel> l = base.Get();foreach (MessageModel mm in l){mm.Message += "（經過用戶驗證）";}return l;}/// <summary>/// 插入Message/// </summary>/// <param name="mm">Message實體對象</param>/// <returns></returns>public override bool Insert(MessageModel mm){// 在這里擴展功能return base.Insert(mm);}} }

　　CheckInputWrapper

using System; using System.Collections.Generic; using System.Text;namespace Pattern.Decorator {/// <summary>/// 擴展出輸入驗證的功能（ConcreteDecorator）/// </summary>public class CheckInputWrapper : AbstractMessageWrapper{/// <summary>/// 構造函數/// </summary>/// <param name="abstractMessage">AbstractMessage</param>public CheckInputWrapper(AbstractMessage abstractMessage): base(abstractMessage){}/// <summary>/// 獲取Message/// </summary>/// <returns></returns>public override List<MessageModel> Get(){List<MessageModel> l = base.Get();foreach (MessageModel mm in l){mm.Message += "（經過輸入驗證）";}return l;}/// <summary>/// 插入Message/// </summary>/// <param name="mm">Message實體對象</param>/// <returns></returns>public override bool Insert(MessageModel mm){// 在這里擴展功能return base.Insert(mm);}} }

　　Test

using System; 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.Decorator;public partial class Decorator : System.Web.UI.Page {protected void Page_Load(object sender, EventArgs e){AbstractMessage message = new SqlMessage();AbstractMessageWrapper amr = new CheckUserWrapper(message);Response.Write(amr.Get()[0].Message + " " + amr.Get()[0].PublishTime.ToString());Response.Write("<br />");AbstractMessageWrapper amr2 = new CheckInputWrapper(message);Response.Write(amr2.Get()[0].Message + " " + amr2.Get()[0].PublishTime.ToString());Response.Write("<br />");AbstractMessageWrapper amr3 = new CheckUserWrapper(message);AbstractMessageWrapper amr4 = new CheckInputWrapper(amr3);Response.Write(amr4.Get()[0].Message + " " + amr4.Get()[0].PublishTime.ToString());Response.Write("<br />");} }

　　運行結果
　　SQL方式獲取Message（經過用戶驗證） 2007-5-13 19:34:01
　　SQL方式獲取Message（經過輸入驗證） 2007-5-13 19:34:01
　　SQL方式獲取Message（經過用戶驗證）（經過輸入驗證） 2007-5-13 19:34:01

轉載于:https://www.cnblogs.com/taotaodetuer/p/6183041.html

總結

以上是生活随笔為你收集整理的二十四种设计模式：装饰模式(Decorator Pattern)的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。