二十四种设计模式：代理模式(Proxy Pattern)

代理模式(Proxy Pattern)

介绍
为其他对象提供一个代理以控制对这个对象的访问。

示例
有一个Message实体类，某对象对它的操作有Insert()和Get()方法，用一个代理来控制对这个对象的访问。

　　MessageModel

using System;
using System.Collections.Generic;
using System.Text;

namespace Pattern.Proxy
{
    /// <summary>
    /// Message实体类
    /// </summary>
    public class MessageModel
    {
        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="msg">Message内容</param>
        /// <param name="pt">Message发布时间</param>
        public MessageModel(string msg, DateTime pt)
        {
            this._message = msg;
            this._publishTime = pt;
        }

        private string _message;
        /// <summary>
        /// Message内容
        /// </summary>
        public string Message
        {
            get { return _message; }
            set { _message = value; }
        }

        private DateTime _publishTime;
        /// <summary>
        /// Message发布时间
        /// </summary>
        public DateTime PublishTime
        {
            get { return _publishTime; }
            set { _publishTime = value; }
        }
    }
}

　　IMessage

using System;
using System.Collections.Generic;
using System.Text;

namespace Pattern.Proxy
{
    /// <summary>
    /// 对Message操作的接口
    /// </summary>
    public interface IMessage
    {
        /// <summary>
        /// 获取Message
        /// </summary>
        /// <returns></returns>
        List<MessageModel> Get();

        /// <summary>
        /// 插入Message
        /// </summary>
        /// <param name="mm">Message实体对象</param>
        /// <returns></returns>
        bool Insert(MessageModel mm);
    }
}

　　SqlMessage

using System;
using System.Collections.Generic;
using System.Text;

namespace Pattern.Proxy
{
    /// <summary>
    /// Sql方式操作Message
    /// </summary>
    public class SqlMessage : IMessage
    {
        /// <summary>
        /// 获取Message
        /// </summary>
        /// <returns></returns>
        public List<MessageModel> Get()
        {
            List<MessageModel> l = new List<MessageModel>();
            l.Add(new MessageModel("SQL方式获取Message", DateTime.Now));

            return l;
        }

        /// <summary>
        /// 插入Message
        /// </summary>
        /// <param name="mm">Message实体对象</param>
        /// <returns></returns>
        public bool Insert(MessageModel mm)
        {
            // 代码略
            return true;
        }
    }
}

　　MessageProxy

using System;
using System.Collections.Generic;
using System.Text;

namespace Pattern.Proxy
{
    /// <summary>
    /// 代理类
    /// </summary>
    public class MessageProxy : IMessage
    {
        SqlMessage _sqlMessage;

        /// <summary>
        /// 构造函数
        /// </summary>
        public MessageProxy()
        {
            _sqlMessage = new SqlMessage();
        }

        /// <summary>
        /// 获取Message
        /// </summary>
        /// <returns></returns>
        public List<MessageModel> Get()
        {
            return _sqlMessage.Get();
        }

        /// <summary>
        /// 插入Message
        /// </summary>
        /// <param name="mm">Message实体对象</param>
        /// <returns></returns>
        public bool Insert(MessageModel mm)
        {
            return _sqlMessage.Insert(mm);
        }
    }
}

　　Client

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.Proxy;

public partial class Proxy : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        MessageProxy m = new MessageProxy();
        Response.Write(m.Insert(new MessageModel("插入", DateTime.Now)));
        Response.Write("<br />");
        Response.Write(m.Get()[0].Message + " " + m.Get()[0].PublishTime.ToString());
    }
}

　　运行结果
　　True
　　SQL方式获取Message 2007-4-1 16:31:24