数据库层抽象工厂解决方案归档[不断升级版]

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    简单工厂模式就是根据提供给它的数据,返回几个可能类中的一个类的实例.通常它返回的类都有一个共同的父类和共同的方法,但是每个方法执行的任务不同,而且根据不同的数据进行了优化。比如X是一个基类,xy和xz是从它派生出来的,XFactory类根据给出的参数决定返回那一个子类,返回那一个类的实例与程序员无关,因为这些类有同样的方法,只是实现不同,返回那个类的实例取决于工厂,工厂功能可能很复杂,但通常都是相当简间的.

    接下来我们用一个例子来说明这个简单的工厂模式.假如我们要输入一个人的姓名,

    有两个方式,一种是“firstname lastname” 和“fristname,lastname”形式.我们的任务就是要确定lastname和firstname是否是逗号来确定姓名的先后.

第一步,设计一个父类:

    public class CName
    {
        protected  string frName ,lName;
        public string getFristName() { return frName;}
       
public string getLastName() { return lName;}
    }

第二步,设计两个子类,它是由类CName的派生的。它们现实了接口,并在构造function中将名字分成了两部分.在CFirstFirst类中,做了一个简单的假设:最后一个空格前面的所有部分都属与firstname.

    public class CFirstFirst : CName 
    {
        public CFirstFirst (string sName) 
        {
            int i = sName.Trim().Indexof(” “);
            if ( i >0 ) 
            { 
                frName  = name.Substring(0,i).Trim();
               
lName = name.Substring(i+1).Trim();
           
}
           
else  
            {
                lName = sName;
                frName = “”;
            }
        }
    }

     在LastFist类中,用逗号给lastname划分界限.当空格或逗号不存在时,两个类都提供了错误校正处理.

    public class LastFrist  :CName  
    {
        public LastFrist(string sName) 
        {
            int i = sName.Indexof(”,”);
            if ( i>0 ) 
            {
                if ( i >0 ) 
                { 
                    lName = name.Substring(0,i).Trim();
                    frName = name.Substring(i+1).Trim();
                }
                else  
                {
                    lName = sName;
                    frName = “”;
                }
            }
        }
    }

两种情况下,都把分开的名字保存在基类的CName中保护变量中.所以在派生类中根本不需要任何getFirstName和getLastName方法,因为基类中已给出.

第三步: 构造简单工厂.

     现在很容易给出简单工厂类.只检查逗号来决定返回那个类的实例

    public class NameFactory ()
    { 
        public CName  getName(string sname)   
        {
            int i = sname.Indexof(”,”);
            if ( i >0 )
            {
                return new LastFrist  (sname);
            }
            else
            {
                return new CFirstFirst (sname);
            }
        }
    }

第四步。使用工厂类:

    string sName = “cedy hao”;
    NameFactory  nf = new NameFactory ();
    CName  name = nf.getName(sName);
    string sFristName = name.getFristName();
    string sLastName = name.getLastName();

    这种方法把和数据相关的问题与类的其它的方法分隔开来。采用抽象工厂模式设计出的系统类图如下:




数据库层抽象工厂解决方案归档:


(1)AbstractDbFactory.cs

using System;
using System.Data;

namespace DbService
{
    /// <summary>
    /// 数据库抽象工厂接口
    /// </summary>

    public interface AbstractDbFactory
    {
        /// <summary>
        /// 建立默认连接
        /// </summary>
        /// <returns>数据库连接</returns>

        IDbConnection CreateConnection();

        /// <summary>
        /// 根据连接字符串建立Connection对象
        /// </summary>
        /// <param name="strConn">连接字符串</param>
        /// <returns>Connection对象</returns>

        IDbConnection CreateConnection(string strConn);

        /// <summary>
        /// 建立Command对象
        /// </summary>
        /// <returns>Command对象</returns>

        IDbCommand CreateCommand();

        /// <summary>
        /// 建立DataAdapter对象
        /// </summary>
        /// <returns>DataAdapter对象</returns>

        IDbDataAdapter CreateDataAdapter();

        /// <summary>
        /// 根据Connection建立Transaction
        /// </summary>
        /// <param name="myDbConnection">Connection对象</param>
        /// <returns>Transaction对象</returns>

        IDbTransaction CreateTransaction(IDbConnection myDbConnection);

        /// <summary>
        /// 根据Command建立DataReader
        /// </summary>
        /// <param name="myDbCommand">Command对象</param>
        /// <returns>DataReader对象</returns>

        IDataReader CreateDataReader(IDbCommand myDbCommand);

        /// <summary>
        /// 获得连接字符串
        /// </summary>
        /// <returns>连接字符串</returns>

        string GetConnectionString();
    }
}

(2)Factory.cs

using System;
using System.Configuration;

namespace DbService
{
    /// <summary>
    /// Factory类
    /// </summary>

    public sealed class Factory
    {
        private static volatile Factory singleFactory = null;
        private static object syncObj = new object();
        
       
/// <summary>
        /// Factory类构造函数
        /// </summary>

        private Factory()
        {
        }

        /// <summary>
        /// 获得Factory类的实例
        /// </summary>
        /// <returns>Factory类实例</returns>

        public static Factory GetInstance()
        {
            if(singleFactory == null)
            {
                lock(syncObj)
                {
                    if(singleFactory == null)
                    {
                        singleFactory = new Factory();
                    }
                }
            }
            return singleFactory;
        }

        /// <summary>
        /// 建立Factory类实例
        /// </summary>
        /// <returns>Factory类实例</returns>

        public AbstractDbFactory CreateInstance()
        {
            AbstractDbFactory abstractDbFactory = null;
            switch(ConfigurationSettings.AppSettings["DatabaseType"].ToLower())
            {
                case "sqlserver":
                {
                    abstractDbFactory = new SqlFactory();
                    break;
                }
                case "oledb":
                {
                    abstractDbFactory = new OleDbFactory();
                    break;
                }
                case "odbc":
                {
                    abstractDbFactory = new OdbcFactory();
                    break;
                }
            }   
            return abstractDbFactory;
        }
    }
}

     以下3个类分别是Factory针对SqlServer专用连接、OleDb连接和Odbc连接时的具体实现:

(3)SqlFactory.cs

using System;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

namespace DbService
{
    /// <summary>
    /// 针对SqlServer专用连接的工厂
    /// </summary>

    public class SqlFactory : AbstractDbFactory
    {
        /// <summary>
        /// 构造函数
        /// </summary>

        public SqlFactory()
        {
        }

        /// <summary>
        /// 建立默认Connection对象
        /// </summary>
        /// <returns>Connection对象</returns>
        public IDbConnection CreateConnection()
        {
            return new SqlConnection();
        }

        /// <summary>
        /// 根据连接字符串建立Connection对象
        /// </summary>
        /// <param name="strConn">连接字符串</param>
        /// <returns>Connection对象</returns>

        public IDbConnection CreateConnection(string strConn)
        {
            return new SqlConnection(strConn);
        }

        /// <summary>
        /// 建立Command对象
        /// </summary>
        /// <returns>Command对象</returns>

        public IDbCommand CreateCommand()
        {
            return new SqlCommand();
        }

        /// <summary>
        /// 建立DataAdapter对象
        /// </summary>
        /// <returns>DataAdapter对象</returns>

        public IDbDataAdapter CreateDataAdapter()
        {
            return new SqlDataAdapter();
        }

        /// <summary>
        /// 根据Connection建立Transaction
        /// </summary>
        /// <param name="myDbConnection">Connection对象</param>
        /// <returns>Transaction对象</returns>

        public IDbTransaction CreateTransaction(IDbConnection myDbConnection)
        {
            return myDbConnection.BeginTransaction();
        }

        /// <summary>
        /// 根据Command建立DataReader
        /// </summary>
        /// <param name="myDbCommand">Command对象</param>
        /// <returns>DataReader对象</returns>

        public IDataReader CreateDataReader(IDbCommand myDbCommand)
        {
            return myDbCommand.ExecuteReader();
        }

        /// <summary>
        /// 获得连接字符串
        /// </summary>
        /// <returns>连接字符串</returns>

        public string GetConnectionString()
        {
            string strServer = ConfigurationSettings.AppSettings["SqlServerServer"];
            string strDatabase = ConfigurationSettings.AppSettings["SqlServerDatabase"];
            string strUid = ConfigurationSettings.AppSettings["SqlServerUid"];
            string strPwd = ConfigurationSettings.AppSettings["SqlServerPwd"];
            string strConnectionString = "Server = " + strServer + "; Database = " + strDatabase + "; Uid = " + strUid + "; Pwd = " + strPwd + ";";
            return strConnectionString;
        }
    }
}

(4)OleDbFactory.cs

using System;
using System.Data;
using System.Data.OleDb;
using System.Configuration;

namespace DbService
{
    /// <summary>
    /// 针对OleDb连接的工厂
    /// </summary>

    public class OleDbFactory : AbstractDbFactory
    {
        /// <summary>
        /// 构造函数
        /// </summary>

        public OleDbFactory()
        {
        }

        /// <summary>
        /// 建立默认Connection对象
        /// </summary>
        /// <returns>Connection对象</returns>

        public IDbConnection CreateConnection()
        {
            return new OleDbConnection();
        }

        /// <summary>
        /// 根据连接字符串建立Connection对象
        /// </summary>
        /// <param name="strConn">连接字符串</param>
        /// <returns>Connection对象</returns>

        public IDbConnection CreateConnection(string strConn)
        {
            return new OleDbConnection(strConn);
        }

        /// <summary>
        /// 建立Command对象
        /// </summary>
        /// <returns>Command对象</returns>

        public IDbCommand CreateCommand()
        {
            return new OleDbCommand();
        }

        /// <summary>
        /// 建立DataAdapter对象
        /// </summary>
        /// <returns>DataAdapter对象</returns>

        public IDbDataAdapter CreateDataAdapter()
        {
            return new OleDbDataAdapter();
        }

        /// <summary>
        /// 根据Connection建立Transaction
        /// </summary>
        /// <param name="myDbConnection">Connection对象</param>
        /// <returns>Transaction对象</returns>

        public IDbTransaction CreateTransaction(IDbConnection myDbConnection)
        {
            return myDbConnection.BeginTransaction();   
        }

        /// <summary>
        /// 根据Command建立DataReader
        /// </summary>
        /// <param name="myDbCommand">Command对象</param>
        /// <returns>DataReader对象</returns>

        public IDataReader CreateDataReader(IDbCommand myDbCommand)
        {
            return myDbCommand.ExecuteReader();
        }

        /// <summary>
        /// 获得连接字符串
        /// </summary>
        /// <returns>连接字符串</returns>

        public string GetConnectionString()
        {
            string strProvider = ConfigurationSettings.AppSettings["OleDbProvider"];
            string strDataSource = ConfigurationSettings.AppSettings["OleDbDataSource"];
            string strConnectionString = "Provider = " + strProvider + ";Data Source = " + strDataSource + ";";
            return strConnectionString;
        }
    }
}

(5)OdbcFactory.cs

using System;
using System.Data;
using System.Data.Odbc;
using System.Configuration;

namespace DbService
{
    /// <summary>
    /// 针对Odbc连接的工厂
    /// </summary>

    public class OdbcFactory : AbstractDbFactory
    {
        /// <summary>
        /// 构造函数
        /// </summary>

        public OdbcFactory()
        {
        }

        /// <summary>
        /// 建立默认Connection对象
        /// </summary>
        /// <returns>Connection对象</returns>

        public IDbConnection CreateConnection()
        {
            return new OdbcConnection();
        }

        /// <summary>
        /// 根据连接字符串建立Connection对象
        /// </summary>
        /// <param name="strConn">连接字符串</param>
        /// <returns>Connection对象</returns>

        public IDbConnection CreateConnection(string strConn)
        {
            return new OdbcConnection(strConn);
        }

        /// <summary>
        /// 建立Command对象
        /// </summary>
        /// <returns>Command对象</returns>

        public IDbCommand CreateCommand()
        {
            return new OdbcCommand();
        }

        /// <summary>
        /// 建立DataAdapter对象
        /// </summary>
        /// <returns>DataAdapter对象</returns>

        public IDbDataAdapter CreateDataAdapter()
        {
            return new OdbcDataAdapter();
        }

        /// <summary>
        /// 根据Connection建立Transaction
        /// </summary>
        /// <param name="myDbConnection">Connection对象</param>
        /// <returns>Transaction对象</returns>

        public IDbTransaction CreateTransaction(IDbConnection myDbConnection)
        {
            return myDbConnection.BeginTransaction();
        }

        /// <summary>
        /// 根据Command建立DataReader
        /// </summary>
        /// <param name="myDbCommand">Command对象</param>
        /// <returns>DataReader对象</returns>

        public IDataReader CreateDataReader(IDbCommand myDbCommand)
        {
            return myDbCommand.ExecuteReader();
        }

        /// <summary>
        /// 获得连接字符串
        /// </summary>
        /// <returns></returns>

        public string GetConnectionString()
        {
            string strDriver = ConfigurationSettings.AppSettings["OdbcDriver"];
            string strDBQ = ConfigurationSettings.AppSettings["OdbcDBQ"];
            string strConnectionString = "Driver={" + strDriver + "}; DBQ=" + strDBQ + ";";
            return strConnectionString;   
        }
    }
}

 

用C#实现的数据库抽象工厂(三)

     以下是在应用时真正要调用到的类:

(6)DbAccess.cs

using System;
using System.Data;

namespace DbService
{
    /// <summary>
    /// DbAccess类,即进行数据库访问时需要调用的类
    /// </summary>

    public sealed class DbAccess
    {
        /// <summary>
        /// DbAccess构造函数
        /// </summary>

        private DbAccess()
        {
        }

        /// <summary>
        /// 无条件查询操作,即查询表中所有记录
        /// </summary>
        /// <param name="strTableName">表名</param>
        /// <param name="strColumn">列名组</param>
        /// <returns>无条件查询结果</returns>

        public static DataSet SelectAll(string strTableName, string[] strColumn)
        {
            DataSet ds = new DataSet();
            Factory factory = Factory.GetInstance();
            AbstractDbFactory abstractDbFactory = factory.CreateInstance();
            IDbConnection concreteDbConn = abstractDbFactory.CreateConnection();
            concreteDbConn.ConnectionString = abstractDbFactory.GetConnectionString();
            concreteDbConn.Open();
            IDbCommand concreteDbCommand = abstractDbFactory.CreateCommand();
            IDbTransaction concreteDbTrans = abstractDbFactory.CreateTransaction(concreteDbConn);
            concreteDbCommand.Connection = concreteDbConn;
            concreteDbCommand.Transaction = concreteDbTrans;
            IDbDataAdapter concreteDbAdapter = abstractDbFactory.CreateDataAdapter();
            try
            {
                string strSql = "SELECT ";
                for(int i = 0; i < strColumn.Length - 1; i++)
                {
                    strSql += (strColumn[i] + ", ");
                }
                strSql += (strColumn[strColumn.Length - 1] + " FROM " + strTableName);
                concreteDbCommand.CommandText = strSql;
                concreteDbAdapter.SelectCommand = concreteDbCommand;    
                concreteDbAdapter.Fill(ds);
                concreteDbTrans.Commit();
            }
            catch
            {
                concreteDbTrans.Rollback();
                ds.Clear();
                throw;
            }
            finally
            {
                concreteDbConn.Close();
            }  
            return ds;
        }

        /// <summary>
        /// 条件查询操作
        /// </summary>
        /// <param name="strTableName">表名</param>
        /// <param name="strColumn">列名组</param>
        /// <param name="strCondition">条件</param>
        /// <returns>条件查询结果</returns>

        public static DataSet Select(string strTableName, string[] strColumn, string strCondition)
        {
            DataSet ds = new DataSet();
            Factory factory = Factory.GetInstance();
            AbstractDbFactory abstractDbFactory = factory.CreateInstance();
            IDbConnection concreteDbConn = abstractDbFactory.CreateConnection();
            concreteDbConn.ConnectionString = abstractDbFactory.GetConnectionString();
            concreteDbConn.Open();
            IDbCommand concreteDbCommand = abstractDbFactory.CreateCommand();
            IDbTransaction concreteDbTrans = abstractDbFactory.CreateTransaction(concreteDbConn);
            concreteDbCommand.Connection = concreteDbConn;
            concreteDbCommand.Transaction = concreteDbTrans;
            IDbDataAdapter concreteDbAdapter = abstractDbFactory.CreateDataAdapter();
            try
            {
                string strSql = "SELECT ";
                for(int i = 0; i < strColumn.Length - 1; i++)
                {
                    strSql += (strColumn[i] + ", ");
                }
                strSql += (strColumn[strColumn.Length - 1] + " FROM " + strTableName + " WHERE " + strCondition);
                concreteDbCommand.CommandText = strSql;
                concreteDbAdapter.SelectCommand = concreteDbCommand;    
                concreteDbAdapter.Fill(ds);
                concreteDbTrans.Commit();
            }
            catch
            {
                concreteDbTrans.Rollback();
                ds.Clear();
                throw;
            }
            finally
            {
                concreteDbConn.Close();
            }
            return ds;
        }

        /// <summary>
        /// 单条记录的插入操作
        /// </summary>
        /// <param name="strTableName">表名</param>
        /// <param name="strColumn">列名组</param>
        /// <param name="strValue">值组</param>

        public static void Insert(string strTableName, string[] strColumn, object[] strValue)
        {
            Factory factory = Factory.GetInstance();
            AbstractDbFactory abstractDbFactory = factory.CreateInstance();
            IDbConnection concreteDbConn = abstractDbFactory.CreateConnection();
            concreteDbConn.ConnectionString = abstractDbFactory.GetConnectionString();   
            concreteDbConn.Open();
            IDbCommand concreteDbCommand = abstractDbFactory.CreateCommand();
            IDbTransaction concreteDbTrans = abstractDbFactory.CreateTransaction(concreteDbConn);
            concreteDbCommand.Connection = concreteDbConn;
            concreteDbCommand.Transaction = concreteDbTrans;
            try
            {
                string strSql = "INSERT INTO " + strTableName + " (";
                for(int i = 0; i < strColumn.Length - 1; i++)
                {
                    strSql += (strColumn[i] + ", ");
                }
                strSql += (strColumn[strColumn.Length - 1] + ") VALUES ('");
                for(int i = 0; i < strValue.Length - 1; i++)
                {
                    strSql += (strValue[i] + "', '");
                }
                strSql += (strValue[strValue.Length - 1] + "')");
                concreteDbCommand.CommandText = strSql;
                concreteDbCommand.ExecuteNonQuery();
                concreteDbTrans.Commit();
            }
            catch
            {
                concreteDbTrans.Rollback();
                throw;
            }
            finally
            {
                concreteDbConn.Close();
            }   
        }

        /// <summary>
        /// 批量记录的插入操作,即可一次向多张表中插入不同的批量记录
        /// </summary>
        /// <param name="ds">批量记录组成的DataSet,DataSet中的各个DataTable名为表名,各DataTable中的DataColumn名为列名</param>

        public static void InsertSet(ref DataSet ds)
        {
            Factory factory = Factory.GetInstance();
            AbstractDbFactory abstractDbFactory = factory.CreateInstance();
            IDbConnection concreteDbConn = abstractDbFactory.CreateConnection();
            concreteDbConn.ConnectionString = abstractDbFactory.GetConnectionString();   
            concreteDbConn.Open();
            IDbCommand concreteDbCommand = abstractDbFactory.CreateCommand();
            IDbTransaction concreteDbTrans = abstractDbFactory.CreateTransaction(concreteDbConn);
            concreteDbCommand.Connection = concreteDbConn;
            concreteDbCommand.Transaction = concreteDbTrans;
            try
            {
                foreach(DataTable dt in ds.Tables)
                {
                    foreach(DataRow dr in dt.Rows)
                    {
                        string strSql = "INSERT INTO " + dt.TableName + " (";
                        for(int i = 0; i < dt.Columns.Count - 1; i++)
                        {
                            strSql += (dt.Columns[i].Caption + ", ");
                        }
                        strSql += (dt.Columns[dt.Columns.Count - 1].Caption + ") VALUES ('");
                        for(int i = 0; i < dt.Columns.Count - 1; i++)
                        {
                            strSql += (dr[i] + "', '");
                        }
                        strSql += (dr[dt.Columns.Count - 1] + "')");
                        concreteDbCommand.CommandText = strSql;
                        concreteDbCommand.ExecuteNonQuery();
                    }
                }
                concreteDbTrans.Commit();
            }

            catch
            {
                concreteDbTrans.Rollback();
                throw;
            }

            finally
            {
                concreteDbConn.Close();
            }   
        }

        /// <summary>
        /// 无条件删除操作,即删除表中所有记录
        /// </summary>
        /// <param name="strTableName">表名</param>

        public static void DeleteAll(string strTableName)
        {
            Factory factory = Factory.GetInstance();
            AbstractDbFactory abstractDbFactory = factory.CreateInstance();
            IDbConnection concreteDbConn = abstractDbFactory.CreateConnection();
            concreteDbConn.ConnectionString = abstractDbFactory.GetConnectionString();
            concreteDbConn.Open();
            IDbCommand concreteDbCommand = abstractDbFactory.CreateCommand();
            IDbTransaction concreteDbTrans = abstractDbFactory.CreateTransaction(concreteDbConn);
            concreteDbCommand.Connection = concreteDbConn;
            concreteDbCommand.Transaction = concreteDbTrans;
            try
            {
                string strSql = "DELETE FROM " + strTableName;
                concreteDbCommand.CommandText = strSql;
                concreteDbCommand.ExecuteNonQuery();
                concreteDbTrans.Commit();
            }
            catch
            {
                concreteDbTrans.Rollback();
                throw;
            }
            finally
            {
                concreteDbConn.Close();
            }   
        }

        /// <summary>
        /// 条件删除操作
        /// </summary>
        /// <param name="strTableName">表名</param>
        /// <param name="strCondition">条件</param>

        public static void Delete(string strTableName, string strCondition)
        {
            Factory factory = Factory.GetInstance();
            AbstractDbFactory abstractDbFactory = factory.CreateInstance();
            IDbConnection concreteDbConn = abstractDbFactory.CreateConnection();
            concreteDbConn.ConnectionString = abstractDbFactory.GetConnectionString();
            concreteDbConn.Open();
            IDbCommand concreteDbCommand = abstractDbFactory.CreateCommand();
            IDbTransaction concreteDbTrans = abstractDbFactory.CreateTransaction(concreteDbConn);
            concreteDbCommand.Connection = concreteDbConn;
            concreteDbCommand.Transaction = concreteDbTrans;
            try
            {
                string strSql = "DELETE FROM " + strTableName + " WHERE " + strCondition;
                concreteDbCommand.CommandText = strSql;
                concreteDbCommand.ExecuteNonQuery();
                concreteDbTrans.Commit();
            }
            catch
            {
                concreteDbTrans.Rollback();
                throw;
            }
            finally
            {
                concreteDbConn.Close();
            }   
        }

        /// <summary>
        /// 无条件更新操作,即更新表中所有记录
        /// </summary>
        /// <param name="strTableName">表名</param>
        /// <param name="strColumn">列名组</param>
        /// <param name="strValue">值组</param>

        public static void UpdateAll(string strTableName, string[] strColumn, object[] strValue)
        {
            Factory factory = Factory.GetInstance();
            AbstractDbFactory abstractDbFactory = factory.CreateInstance();   
            IDbConnection concreteDbConn = abstractDbFactory.CreateConnection();
            concreteDbConn.ConnectionString = abstractDbFactory.GetConnectionString();
            concreteDbConn.Open();
            IDbCommand concreteDbCommand = abstractDbFactory.CreateCommand();
            IDbTransaction concreteDbTrans = abstractDbFactory.CreateTransaction(concreteDbConn);
            concreteDbCommand.Connection = concreteDbConn;
            concreteDbCommand.Transaction = concreteDbTrans;
            try
            {
                string strSql = "UPDATE " + strTableName + " SET ";
                for(int i = 0; i < strColumn.Length - 1; i++)
                {
                    strSql += (strColumn[i] + " = '" + strValue[i] + "', ");
                }
                strSql += (strColumn[strColumn.Length - 1] + " = '" + strValue[strValue.Length - 1] + "' ");
                concreteDbCommand.CommandText = strSql;
                concreteDbCommand.ExecuteNonQuery();
                concreteDbTrans.Commit();
            }
            catch
            {
                concreteDbTrans.Rollback();
                throw;
            }
            finally
            {
                concreteDbConn.Close();
            }
        }

        /// <summary>
        /// 条件更新操作
        /// </summary>
        /// <param name="strTableName">表名</param>
        /// <param name="strColumn">列名组</param>
        /// <param name="strValue">值组</param>
        /// <param name="strCondition">条件</param>
        public static void Update(string strTableName, string[] strColumn, object[] strValue, string strCondition)
        {
            Factory factory = Factory.GetInstance();
            AbstractDbFactory abstractDbFactory = factory.CreateInstance();   
            IDbConnection concreteDbConn = abstractDbFactory.CreateConnection();
            concreteDbConn.ConnectionString = abstractDbFactory.GetConnectionString();
            concreteDbConn.Open();
            IDbCommand concreteDbCommand = abstractDbFactory.CreateCommand();
            IDbTransaction concreteDbTrans = abstractDbFactory.CreateTransaction(concreteDbConn);
            concreteDbCommand.Connection = concreteDbConn;
            concreteDbCommand.Transaction = concreteDbTrans;
            try
            {
                string strSql = "UPDATE " + strTableName + " SET ";
                for(int i = 0; i < strColumn.Length - 1; i++)
                {
                    strSql += (strColumn[i] + " = '" + strValue[i] + "', ");
                }
                strSql += (strColumn[strColumn.Length - 1] + " = '" + strValue[strValue.Length - 1] + "' " + " WHERE " + strCondition);
                concreteDbCommand.CommandText = strSql;
                concreteDbCommand.ExecuteNonQuery();
                concreteDbTrans.Commit();
            }
            catch
            {
                concreteDbTrans.Rollback();
                throw;
            }
            finally
            {
                concreteDbConn.Close();
            }
        }
    }
}

最后一步,在Web.config中的根结点configuration下增加一些关于数据库连接字符串的变量:

<appSettings>
 
    <add key="DatabaseType" value="SqlServer" />
 
    <add key="SqlServerServer" value="flyingyoko" />
    <add key="SqlServerDatabase" value="test" />
    <add key="SqlServerUid" value="sa" />
    <add key="SqlServerPwd" value="****" />
 
    <add key="OleDbProvider" value="Microsoft.jet.oledb.4.0" />
    <add key="OleDbDataSource" value="D:\test.mdb" />
 
    <add key="OdbcDriver" value="Microsoft Access Driver (*.mdb)" />
    <add key="OdbcDBQ" value="d:\test.mdb" />
      
</appSettings>

     现在一切OK,大家可以通过改变Web.config中的变量来使用不同的数据库连接方式(SqlServer专用连接、OleDb连接和Odbc连接)连接不同的数据库,同时整个使用仍通过DbAccess,不受任何影响。

    attention:(原始资料出自何处已忘V_V)

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