反射+泛型+缓存 ASP.NET的数据层通用类

using System;
using System.Collections.Generic;
using System.Text;
using System.Reflection ;
using System.Data ;
using BaiChang.HealBlog.Model ;
using System.Data.SqlClient;
using BaiChang.SqlDBUtility;

namespace BaiChang.Middle.Front
{
    public  class DataAccess<T>where T:new()
    {
        #region Main Part

        public static DataAccess<T> GetDataAccess()
        {
            string name = "DataAccess" + typeof(T).Name;
            DataAccess<T> tObj = Utils.CurrentPage.Cache[name] as DataAccess<T>;

            object obj = new object();
            if (tObj == null)
            {
                Utils.CurrentPage.Cache[name] = typeof(DataAccess < T>).Assembly.CreateInstance(typeof(DataAccess<T>).Name);
                tObj = Utils.CurrentPage.Cache[name] as DataAccess<T>;
            }
            return tObj;
        }

        public static string ToSetString(string name)
        {
            string formate = "{0}={1}";
            return string.Format(formate, name, name);
        }

        public static List<T> ToModel(SqlDataReader reader)
        {
            Dictionary<string, PropertyInfo> ps = new Dictionary<string, PropertyInfo>();
            foreach (PropertyInfo p in typeof (T).GetProperties ())
            {
                ps.Add(p.Name, p);
            }

            List<T> ms=new List<T> ();
            while (reader.Read())
            {
                T m = new T();
                object[] objs = null;
                int count = reader.GetValues(objs);
                int i = 0;
                foreach (object o in objs)
                {
                    ps[reader.GetName(i)].SetValue(m, o, null);
                    i++;
                }
                ms.Add(m);
            }
            return ms;
        }
        #region Properties
        //当前实体类型
        Type entityType;
        Type type
        {
            get
            {
                if(entityType ==null)
                entityType = typeof(T);
                return entityType;
            }
        }

        //实体的所有属性
        PropertyInfo[] propertyInfos;
        PropertyInfo[] pros
        {
            get
            {
                if (propertyInfos == null) propertyInfos = this.type.GetProperties();
                return propertyInfos;
            }
        }

        //相对应的表名
        string _tableName=string.Empty ;
        string tableName
        {
            get
            {
                if (_tableName == string.Empty)
                {
                    string className = typeof(T).Name;

                    switch (className)
                    {
                        case "Users":
                        case "Role_Node_Permissions":
                            _tableName = "PE_" + className;
                        default:
                            _tableName = "HB_" + className;
                    }
                }
            }
        }
        #endregion
        #endregion


        #region  成员方法

        /// <summary>
        /// 得到最大ID
        /// </summary>
        public int GetMaxId()
        {
            return DbHelperSQL.GetMaxID(pros[0].Name , tableName);
        }

        /// <summary>
        /// 得到最大值
        /// </summary>

        /// <summary>
        /// 是否存在该记录
        /// </summary>
        public bool Exists(int ID)
        {
            StringBuilder strSql = new StringBuilder();
            strSql.Append("select count(1) from ");
            strSql.Append(tableName);
            strSql.Append(" where ");
            strSql.Append(ToSetString(pros[0].Name));
            SqlParameter[] parameters = {
                    new SqlParameter("@"+pros[0].Name, SqlDbType.Int,4)};
            parameters[0].Value = ID;

            return DbHelperSQL.Exists(strSql.ToString(), parameters);
        }


        /// <summary>
        /// 增加一条数据
        /// </summary>
        public int Add(T model)
        {
            StringBuilder strSql = new StringBuilder();

            strSql .Append ("insert into ");
            strSql .Append (tableName );
            strSql.Append(" (");

            //生成XXXvalues(XXX)
            int i=1;
            foreach (PropertyInfo p in pros)
            {
                strSql .Append (p.Name );
                if (i != pros.Length)
                    strSql.Append(",");
                i++;
            }
            strSql.Append(") values (");
            i = 1;
            foreach (PropertyInfo p in pros)
            {
                strSql.Append("@");
                strSql.Append(p.Name);
                if (i != pros.Length)
                    strSql.Append(",");
                i++;
            }
            strSql.Append(");select @@IDENTITY");
            
            //生成sqlparameters
            List<SqlParameter> sqlpars = new List<SqlParameter>();
            foreach (PropertyInfo p in pros)
            {
                SqlParameter sp = new SqlParameter("@" + p.Name, p.GetValue(model, null));
                sqlpars.Add(sp);
            }
            object obj = DbHelperSQL.GetSingle(strSql.ToString(), sqlpars .ToArray ());
            if (obj == null)
            {
                return 1;
            }
            else
            {
                return Convert.ToInt32(obj);
            }
        }

        /// <summary>
        /// 更新一条数据
        /// </summary>
        public void Update(T model)
        {
            StringBuilder strSql = new StringBuilder();
            strSql.Append("update ");
            strSql .Append (tableName );
            strSql .Append (" set ");
            int i=1;
            foreach (PropertyInfo p in pros)
            {
                strSql.Append(ToSetString(p.Name));
                if(i!=pros.Length )
                    strSql .Append (",");
                i++;
            }
            strSql.Append(" where ");
            strSql.Append(ToSetString(pros[0].Name));
            //生成sqlparameters
            List<SqlParameter> sqlpars = new List<SqlParameter>();
            foreach (PropertyInfo p in pros)
            {
                SqlParameter sp = new SqlParameter("@" + p.Name, p.GetValue(model, null));
                sqlpars.Add(sp);
            }

            DbHelperSQL.ExecuteSql(strSql.ToString(), sqlpars .ToArray());
        }

        /// <summary>
        /// 删除一条数据
        /// </summary>
        public void Delete(int ID)
        {

            StringBuilder strSql = new StringBuilder();
            strSql.Append("delete from ");
            strSql.Append(tableName);
            strSql.Append(" where ");
            strSql.Append(ToSetString(pros[0].Name));
            SqlParameter[] parameters = {
                    new SqlParameter("@"+pros [0].Name, SqlDbType.Int,4)};
            parameters[0].Value = ID;

            DbHelperSQL.ExecuteSql(strSql.ToString(), parameters);
        }


        /// <summary>
        /// 得到一个对象实体
        /// </summary>
        public T GetModel(int ID)
        {

            StringBuilder strSql = new StringBuilder();
            strSql.Append("select  top 1 ");
            int i=1;
            foreach (PropertyInfo p in pros)
            {
                strSql.Append(ToSetString(p.Name));
                if(i!=pros.Length )
                    strSql .Append (",");
            }
            strSql .Append (tableName );
            strSql.Append(" where  ");
            strSql.Append(ToSetString(pros[0].Name));
            SqlParameter[] parameters = {
                    new SqlParameter("@"+pros[0].Name, SqlDbType.Int,4)};
            parameters[0].Value = ID;
            List<T> ms;
            using (SqlDataReader reader = DbHelperSQL.ExecuteReader(strSql.ToString (), parameters))
            {
                 ms= ToModel(reader);
                reader.Close();
            }
            if (ms.Count > 0) return ms[0];
            else return default (T);
        }

        /// <summary>
        /// 获得数据列表
        /// </summary>
        public List<T> GetList(string strWhere)
        {
            StringBuilder strSql = new StringBuilder();
            strSql.Append("select * ");
            strSql.Append(" FROM ");
            strSql.Append(tableName);
            if (strWhere.Trim() != "")
            {
                strSql.Append(" where " + strWhere);
            }

            List<T> ms;
            using (SqlDataReader reader = DbHelperSQL.ExecuteReader(strSql.ToString ()))
            {
                ms = ToModel(reader);
                reader.Close();
            }
            if (ms.Count > 0) return ms;
            else return null;
        }

        /// <summary>
        /// 获得前几行数据
        /// </summary>
        public List<T> GetList(int Top, string strWhere, string filedOrder)
        {
            StringBuilder strSql = new StringBuilder();
            strSql.Append("select ");
            if (Top > 0)
            {
                strSql.Append(" top " + Top.ToString());
            }
            strSql.Append(" * ");
            strSql.Append(" FROM  ");
            strSql.Append(tableName);
            if (strWhere.Trim() != "")
            {
                strSql.Append(" where " + strWhere);
            }
            strSql.Append(" order by " + filedOrder);
                        List<T> ms;
            using (SqlDataReader reader = DbHelperSQL.ExecuteReader(strSql.ToString ()))
            {
                ms = ToModel(reader);
                reader.Close();
            }
            if (ms.Count > 0) return ms;
            else return null;
        }
        


         ///<summary>
         ///分页获取数据列表
         ///</summary>
        public List<T> GetList(int PageSize,int PageIndex,string strWhere)
        {
            List<T> ms=GetList(strWhere);
            int startIndex=0, endIndex=0;
            Utils.GetPageArea(ref startIndex, ref endIndex, PageIndex, PageSize, ms.Count);
            List<T> result = new List<T>();
            for (int i = startIndex; i <= endIndex; i++)
            {
                result.Add(ms[i]);
            }
            return result;
        }

        #endregion  成员方法


    }
}

一点想法+一点尝试
还有些问题有待解决^_^

作者：today4king

转载：http://www.cnblogs.com/jinzhao/archive/2009/07/24/1530213.html