手把手教你写ORM（八）

最后我们来解决点遗留问题
首先是读取Attribute的问题

Type tp = target.GetType();
PropertyInfo pp = tp.GetProperty(s);
foreach (object o in pp.GetCustomAttributes(false))
{
    if (o.GetType().Equals(typeof(ParamAttribute)))
    {
        ParamAttribute p = (ParamAttribute)o;
        //这里P就是Attribute的对象啦
        break;
    }
}

大致的方法就是这样子。

还有就是如何通过“NChar”等字符串获取System.Data.SqlDBType这个枚举的类型的值
其实也不难，
SqlDbType ptype = (SqlDbType)System.Enum.Parse(typeof(SqlDbType), "VarChar");
这样子就可以了

最后我们实现一个数据库操作组件就可以把上面内容组合起来了，下面贴的代码是我自己写了个很粗糙的例子上的

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Collections;
using System.Reflection;
using Alexander.Xbase.ClassConfig;
using Alexander.Xbase.Xcache;
using Alexander.Xbase.Xresource;
using Alexander.Xbase.Interface;

namespace Alexander.Xbase.SqlExec
{
    public class Exec: Alexander.Xbase.Interface.IQueriable
    {

        private string ConnectionString;
        private SqlConnection conn;
        private SqlTransaction tran;
        private bool TransOpen;
        private string configpath;
        IQueriable 成员#region IQueriable 成员

        public void Init(string connstr,string configbase)
        {
            ConnectionString = connstr;
            configpath = configbase;
            conn = new SqlConnection(ConnectionString);
            if (conn.State.Equals(ConnectionState.Closed))
            {
                conn.Open();
            }
            
            //throw new Exception("The method or operation is not implemented.");
        }

        public void OpenTranscation()
        {
            TransOpen = true;
            tran = conn.BeginTransaction();
           // throw new Exception("The method or operation is not implemented.");
        }

        public void Commit()
        {
            TransOpen = false;
            tran.Commit();
            tran = null;
            //throw new Exception("The method or operation is not implemented.");
        }

        public void RollBack()
        {
            TransOpen = false;
            tran.Rollback();
            tran = null;
            //throw new Exception("The method or operation is not implemented.");
        }

        public object Query4Object(string action, object target)
        {
            object rs=new object();
            ConfigStruct config = new ConfigStruct(new Resource(configpath + target.GetType().Name+".xml").Data);
            string sql = config.GetSql(action);
            string execsql = MakeExecuteSql(sql);
            string storedsql = MakeValueSql(sql,target);
            string sKey = target.GetType().Name + ":" + storedsql;
            if (config.IsCache(action))
            {
                if (IsInCache(sKey, rs))
                {
                    return ObjCache.GetObject[sKey];
                }
            }
            SqlCommand comm = new SqlCommand(execsql, conn);
            PrepareCommand(comm, execsql, target);
            SqlDataReader sr = comm.ExecuteReader();
            while (sr.Read())
            {
                rs=FillObject(sr, target.GetType());
            }
            sr.Close();
            if (config.IsCache(action))
                ObjCache.Insert(sKey, rs);
            return rs;
            //throw new Exception("The method or operation is not implemented.");
        }

        public void Query4List(string action,ref IList target, object queryparam)
        {
            object rs=new object();
            //SortedList sl = new SortedList();
            ConfigStruct config = new ConfigStruct(new Resource(configpath + queryparam.GetType().Name + ".xml").Data);
            string sql = config.GetSql(action);
            string execsql = MakeExecuteSql(sql);
            string storedsql = MakeValueSql(sql,queryparam);
            string sKey = queryparam.GetType().Name + ":" + storedsql;
            if (config.IsCache(action))
            {
                if (IsInCache(sKey, rs))
                {
                    target = (IList)ObjCache.GetObject[sKey];
                    return;
                }
            }
            SqlCommand comm = new SqlCommand(execsql, conn);
            PrepareCommand(comm, sql, queryparam);
           
            SqlDataReader sr = comm.ExecuteReader();
            int i=0;
            while (sr.Read())
            {
                rs=FillObject(sr, queryparam.GetType());
                target.Add(rs);
            }
            sr.Close();
            if (config.IsCache(action))
            {
                ObjCache.Insert(sKey, target);
            }
            //return sl;
            //throw new Exception("The method or operation is not implemented.");
        }

        public int Query4Page(string action,ref IList target, object queryparam, int pageid, int pagesize,string sort,string direct)
        {
            object rs = new object();
            
            ConfigStruct config = new ConfigStruct(new Resource(configpath + queryparam.GetType().Name+".xml").Data);
            string sql = config.GetSql(action);
            string pagesql = DoPageSql(sql, pageid, pagesize, sort, direct);
            string execsql = MakeExecuteSql(pagesql);
            string storedsql = MakeValueSql(pagesql, queryparam);
            string sKey = queryparam.GetType().Name + ":" + storedsql;
            int count = (int)Count(action,DoCountSql(MakeExecuteSql(sql)), queryparam);
            if (config.IsCache(action))
            {
                if (IsInCache(sKey, rs))
                {
                    target = (IList)ObjCache.GetObject[sKey];
                    return count;
                }
            }
            SqlCommand comm = new SqlCommand(execsql, conn);
            PrepareCommand(comm, sql, queryparam);
           
            SqlDataReader sr = comm.ExecuteReader();
            int i = 0;
            while (sr.Read())
            {
                rs=FillObject(sr, queryparam.GetType());
                target.Add(rs);
            }
            sr.Close();
            if (config.IsCache(action))
            {
                ObjCache.Insert(sKey, target);
            }     
            return count;
            //throw new Exception("The method or operation is not implemented.");
        }

        public int Query4Update(string action, object target)
        {
            object rs = new object();
            ConfigStruct config = new ConfigStruct(new Resource(configpath + target.GetType().Name + ".xml").Data);
            string sql = config.GetSql(action);
            string execsql = MakeExecuteSql(sql);
            string storedsql = MakeValueSql(sql, target);
            string sKey = target.GetType().Name + ":" + storedsql;
            SqlCommand comm = new SqlCommand(execsql, conn);
            PrepareCommand(comm, sql, target);
            int ct=comm.ExecuteNonQuery();
            ObjCache.Flash(target.GetType().Name);
            return ct;
            //throw new Exception("The method or operation is not implemented.");
        }

        public object Query4Count(string action, object target)
        {
            ConfigStruct config = new ConfigStruct(new Resource(configpath + target.GetType().Name + ".xml").Data);
            string sql = config.GetSql(action);
            return Count(action,sql, target);
        }
        public void Close()
        {
            conn.Close();
            //throw new Exception("The method or operation is not implemented.");
        }

        #endregion

        private string DoPageSql(String command, int pageid, int pagesize, string sort, string direct)
        {
            int All = pagesize * pageid;
            StringBuilder PageSql = new StringBuilder("SELECT * FROM (SELECT TOP #PageSize * FROM (SELECT TOP #ALLCount * FROM (#SelectCommand) AS t0 ORDER BY #SortField DESC) AS t1 ORDER BY #SortField ASC) AS t2 ORDER BY #SortField " + direct);
            PageSql.Replace("#PageSize", pagesize.ToString());
            PageSql.Replace("#ALLCount", All.ToString());
            PageSql.Replace("#SelectCommand", command);
            PageSql.Replace("#SortField", sort);
            return PageSql.ToString();
        }

        private string DoCountSql(string command)
        {
            string work = command.ToLower();
            int startindex = work.IndexOf("select") + 7;
            int endindex = work.LastIndexOf("from") - 1;
            work = work.Remove(startindex, endindex - startindex);
            work = work.Insert(startindex, "count(*)");
            return work;
        }

        private object Count(string action,string sql, object target)
        {
            object rs = new object();
            ConfigStruct config = new ConfigStruct(new Resource(configpath + target.GetType().Name+".xml").Data);
            string execsql = MakeExecuteSql(sql);
            string storedsql = MakeValueSql(sql, target);
            string sKey = target.GetType().Name + ":" + storedsql;
            if (config.IsCache(action))
            {
                if (IsInCache(sKey, rs))
                {
                    return ObjCache.GetObject[sKey];
                }
            }
            SqlCommand comm = new SqlCommand(execsql, conn);
            PrepareCommand(comm, sql, target);
            rs = comm.ExecuteScalar();
            if (config.IsCache(action))
            {
                ObjCache.Insert(sKey, rs);
            }
            return rs;
        }

        private string MakeExecuteSql(string RawSql)
        {
            return RawSql.Replace("#", "@");
        }
        private string MakeValueSql(string RawSql,object target)
        {
            SortedList<string, object> paramlist = new SortedList<string, object>();
            string RS=RawSql;
            ConfigStruct.GetParam(RawSql, paramlist, target);
            foreach (string Key in paramlist.Keys)
            {
                RS = RS.Replace("#" + Key, paramlist[Key].ToString());
            }
            return RS;
        }

        private object FillObject(SqlDataReader rd,Type tp)
        {
            string Key=string.Empty;
            object rs = System.Activator.CreateInstance(tp);
            foreach (PropertyInfo pp in tp.GetProperties())
            {

                foreach (object o in pp.GetCustomAttributes(false))
                {
                    if (o.GetType().Equals(typeof(ParamAttribute)))
                    {
                        ParamAttribute p = (ParamAttribute)o;

                        if (p.Srccolumn != null)
                        {
                            Key = p.Srccolumn;
                        }
                        else
                        {
                            Key = pp.Name;
                        }
                        if (rd[Key] != null)
                        {
                            //rs = rd[Key];
                            pp.SetValue(rs, rd[Key], new object[] { });
                        }
                        break;
                    }
                }
            }
            return rs;
        }

        private void PrepareCommand(SqlCommand cmd, string sql, object tar)
        {
            SortedList<string, object> paramdata = new SortedList<string, object>();
            SortedList<string, ParamAttribute> paramstruct = new SortedList<string, ParamAttribute>();
            ConfigStruct.GetParam(sql, paramdata, tar);
            ConfigStruct.GetParamType(sql, paramstruct, tar);
            for (int i = 0; i < paramstruct.Count; i++)
            {
                SqlDbType ptype = (SqlDbType)System.Enum.Parse(typeof(SqlDbType), paramstruct.Values[i].ParameterType);
                cmd.Parameters.Add("@" + paramdata.Keys[i], ptype, paramstruct.Values[i].ParameterLength).Value = paramdata.Values[i];
            }
            if (this.TransOpen)
            {
                cmd.Transaction = this.tran;
            }
        }
        private bool IsInCache(string action, object rs)
        {
            if (ObjCache.GetObject.TryGetValue(action, out rs))
            {
                return true;
            }
            else
            {
                return false;
            }
        }
    }
}

细节上和之前几篇可能有点出入，不过思想是一致的

关于事务的问题我们以后再说
最后附上我穷一晚上功夫写的粗糙的例子作文本系列的结束
希望这两天来写下的问题能够带领菜菜鸟们走进ORM的一些看似神秘的实现细节，有些是我借鉴了其他的源码，有些是完全自己杜撰的，不管怎么说那个粗糙的例子运行还算良好，不过之前没有好好精细设计一下，有点凌乱的感觉。

http://www.81831.com/FileUpload/Xbase.rar 这是那个粗糙的例子
因为公司的测试服务器老挂，我在这里也放一个 https://files.cnblogs.com/Alexander-Lee/Xbase.rar