使用静态工厂模式，通过传入枚举型参数，动态创建访问实例
实现模式上采用基本实现接口，派生类继承基类的虚函数，从而实现代码的耦合较低，有很好的扩展性。
publicenum DBType
...{
Access,
SQL,
DB2,
Oracle,
MySQL
}
publicstaticclass DBAccessFactory
...{
publicstatic IDBAccess Create(DBType type)
...{
IDBAccess IRet = null;
switch (type)
...{
case DBType.Access:
IRet = new Access(type);
break;
case DBType.SQL:
IRet = new SQL(type);
break;
default:
break;
}
return IRet;
}
privateabstractclass DBAccess : IDBAccess
...{
protected DbConnection m_oConn = null;
protectedconststring CON_strServer = "Server";
protectedconststring CON_strDataBase = "Data Source";
protectedconststring CON_strUser = "UID";
protectedconststring CON_strPwd = "PWD";
protectedconststring CON_strConnTimeOut = "Connect Timeout = 2";
private DBType m_eDBType = DBType.Access;
protected DBAccess(DBType type)
...{
this.m_eDBType = type;
}
public DBType DBType
...{
get...{ returnthis.m_eDBType; }
}
publicvoid Init(string strServer, string strDataBase, string strUser, string strPwd)
...{
this.InitConn(strServer, strDataBase, strUser, strPwd);
}
publicvoid Open()
...{
if (this.m_oConn != null)
...{
this.m_oConn.Open();
}
}
publicint RunNoQuery(string strCmd)
...{
int iRet = 0;
try
...{
DbCommand oCmd = this.GetCmd(strCmd);
if (oCmd != null)
...{
iRet = oCmd.ExecuteNonQuery();
}
}
catch (Exception ex)
...{
throw (new Exception(ex.Message));
}
return iRet;
}
publicint GetFiledMax(string strTable, string strField)
...{
int iRet = -1;
DataTable dt = this.RunQuery("Select Max(" + strField + ") From " + strTable);
if (dt != null && dt.Rows.Count == 1)
...{
iRet = dt.Rows[0][0] is DBNull ? 0 : Convert.ToInt32(dt.Rows[0][0]);
}
return iRet;
}
public DataTable RunQuery(string strCmd)
...{
DataTable dt = new DataTable();
DbDataAdapter adp = this.DbAdp;
adp.SelectCommand = this.GetCmd(strCmd);
adp.Fill(dt);
return dt;
}
publicvoid Close()
...{
if (this.m_oConn != null && this.m_oConn.State == System.Data.ConnectionState.Open)
...{
this.m_oConn.Close();
}
}
publicbool TestConn()
...{
bool bRet = true;
try
...{
if (this.m_oConn.State != System.Data.ConnectionState.Open)
...{
this.m_oConn.Open();
}
bRet = this.m_oConn.State == System.Data.ConnectionState.Open;
}
catch
...{
bRet = false;
}
this.Close();
return bRet;
}
publicabstract DataTable Tables ...{ get; }
publicabstract DataTable GetColumns();
publicabstract DataTable GetColumns(string strTable);
protectedabstractvoid InitConn(string strServer, string strDataBase, string strUser, string strPwd);
protectedabstract DbCommand GetCmd(string strCmd);
protectedabstract DbDataAdapter DbAdp ...{ get;}
}
}
