加载的DAL数据访问层的类型

using System;
using System.Collections;
using System.Reflection;
using CSFrameworkV4_5.Core;
using CSFrameworkV4_5.Core.CodeGenerator;
using CSFrameworkV4_5.Server.DataAccess.DAL_Base;

namespace CSFrameworkV4_5.Server.DataAccess
{

    /// <summary>
    /// 加载的DAL数据访问层的类型，注意：此类必须放在数据访问层模块
    /// </summary>
    public static class DALTypeLoader
    {
        //哈希表, 保存已加载的DAL类的引用地址
        private static Hashtable _LoadedDalTypes = null;

        //数据访问层的程序集
        private static Assembly _DALAssembly = null;

        /// <summary>
        /// 数据访问层的程序集
        /// </summary>
        public static Assembly DALAssembly
        {
            get
            {
                if (DALTypeLoader._DALAssembly == null)
                    DALTypeLoader._DALAssembly = typeof(DALTypeLoader).Assembly;

                return DALTypeLoader._DALAssembly;
            }
        }

        static DALTypeLoader()
        {
            _LoadedDalTypes = new Hashtable();
        }

        /// <summary>
        /// 跟据DAL类名创建数据层实例
        /// </summary>
        /// <param name="derivedClassName">DAL类名，如：CSFrameworkV4_5.Server.DataAccess.DAL_Business.dalSO</param>
        /// <returns></returns>
        internal static Type GetDALTypeByClassName(string derivedClassName)
        {
            Type T = DALTypeLoader.DALAssembly.GetType(derivedClassName, true, true);
            return T;
        }

        /// <summary>
        /// 根据表名获取对应的DAL层
        /// </summary>
        /// <param name="tableName">表名</param>
        /// <returns></returns>
        internal static Type GetDALTypeByTableName(string tableName)
        {
            Type _DAL_Type = null;

            #region 获取DAL的Type类型

            //哈希表存在该类,从哈希表取出.
            if (_LoadedDalTypes.ContainsKey(tableName))
                _DAL_Type = _LoadedDalTypes[tableName] as Type;
            else
            {
                //获取DataAccess程序集中所有Public类  
                Type[] types = DALTypeLoader.DALAssembly.GetExportedTypes();

                //枚举程序集中所有Public类  
                foreach (Type T in types)
                {
                    //只查找dalBaseDataDict的子类
                    if (false == T.IsSubclassOf(typeof(dalBaseDataDict))) continue;

                    //查找DefaultORM_UpdateMode特性
                    object[] atts = T.GetCustomAttributes(typeof(DefaultORM_UpdateMode), false);
                    if ((atts == null) || (atts.Length == 0)) continue;

                    //该类有定义DefaultORM_UpdateMode特性
                    DefaultORM_UpdateMode att = atts[0] as DefaultORM_UpdateMode;
                    if (ORM_Tools.GetTableName(att.ORM) == tableName)
                    {
                        _DAL_Type = T;
                        break;
                    }
                }

                //第一次加载后添加到哈希表中, 基于性能优化.
                if (_DAL_Type != null) _LoadedDalTypes.Add(tableName, _DAL_Type);
            }
            #endregion

            return _DAL_Type;
        }

        /// <summary>
        /// 根据ORM模型类全名获取对应的DAL层
        /// </summary>
        /// <param name="ORM_TypeName"></param>
        /// <returns></returns>
        internal static Type GetDALTypeByORM(string ORM_TypeName)
        {
            Type _DAL_Type = null;

            #region 获取_DAL_Type
            //哈希表存在该类,从哈希表取出.
            if (_LoadedDalTypes.ContainsKey(ORM_TypeName))
                _DAL_Type = _LoadedDalTypes[ORM_TypeName] as Type;
            else
            {
                //
                //哈希表不存在,表示第一次加载,需要从CSFrameworkV4_5.Server.DataAccess程序集中查询该类                
                //
                //获取DataAccess程序集中所有Public类  
                Type[] types = DALTypeLoader.DALAssembly.GetExportedTypes();

                //枚举程序集中所有Public类  
                foreach (Type T in types)
                {
                    //只查找dalBaseDataDict的子类
                    if (false == T.IsSubclassOf(typeof(dalBaseDataDict))) continue;

                    //查找DefaultORM_UpdateMode特性
                    object[] atts = T.GetCustomAttributes(typeof(DefaultORM_UpdateMode), false);
                    if ((atts == null) || (atts.Length == 0)) continue;

                    //该类有定义DefaultORM_UpdateMode特性
                    DefaultORM_UpdateMode att = atts[0] as DefaultORM_UpdateMode;
                    if (false == att.IsOverrideClass) continue; //仅查找具体类(子类)

                    //比较ORM的全名是否相同
                    if (att.ORM.FullName.ToUpper() == ORM_TypeName.ToUpper())
                    {
                        _DAL_Type = T;
                        break;
                    }
                }

                //第一次加载后添加到哈希表中, 基于性能优化.
                if (_DAL_Type != null) _LoadedDalTypes.Add(ORM_TypeName, _DAL_Type);
            }
            #endregion

            return _DAL_Type;
        }

    }

}