工厂示例

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Configuration;
using System.Reflection;

namespace Common.DALFactory
{
    /// <summary>
    /// 数据层对象实例创建
    /// </summary>
    public partial class DbFactory
    {
        /// <summary>
        /// 做缓存
        /// </summary>
        private static Dictionary<string, object> dic = new Dictionary<string, object>();

        #region 程序集配置 -static readonly string DALAssembly
        /// <summary>
        /// 程序集配置
        /// </summary>
        private static readonly string DALAssembly = ConfigurationManager.AppSettings["dalAssembly"]; 
        #endregion

        #region 命名空间配置 -static readonly string DALNameSpace
        /// <summary>
        /// 命名空间配置
        /// </summary>
        private static readonly string DALNameSpace = ConfigurationManager.AppSettings["dalNameSpace"]; 
        #endregion

        #region 创建对象实例 -static object CreateInstance(string fullName, string assemblyName)
        /// <summary>
        /// 创建对象实例
        /// </summary>
        /// <param name="fullName">全名称 命名空间.类名</param>
        /// <param name="assemblyName">程序集名称</param>
        /// <returns></returns>
        private static object CreateInstance(string fullName, string assemblyName)
        {
            string key = string.Format("{0}+{1}", assemblyName, fullName);
            if (!dic.ContainsKey(key))
            {
                Assembly assembly = Assembly.Load(assemblyName);    // 加载程序集
                object obj = assembly.CreateInstance(fullName);
                dic.Add(key, obj);
            }
            return dic[key];            
        } 
        #endregion
    }
}