[转]抽象工厂模式：实现ASP.NET访问不同数据库

在ASP.NET网站开发中可能会遇到要更换数据库，如将Aceess换为SQL Server ，由于Aceess引用System.Data.OleDb命名空间，SQL Server引用System.Data.SqlClient命名空间。在一般程序代码中我们需要更改连接字符串，ADO.NET数据访问命令对象，最麻烦的是不同数据库有各自不同Sql命令。我们可以使用抽象工厂模式实现ASP.NET访问不同数据库。

 

1、抽象工厂模式（Abstract Factory）：提供一个创建一系列相互依赖对象的接 口，而无需指定他们的具体类。

2、一般组成：抽象 产品接口，具体产品类，抽象工厂接口，具体工厂类，客户端代码

3、作用：易于交换 产品系列，在一个应用中只需在初始化的时候出现一次，这就使得改变一个应用的具体工厂的具体工厂变得非常容易，只需改变具体工厂即可使用不同的产品配置

让具体的创建实例过程与客户端分离，客户端是通过他们的抽象 类接口操纵实例，产品的具体类名也被具体工厂是实现分离，不会出现在客户代码中。

 

 

网上提供的代码基本是为了讲解说 明C#设计模式，由C#控制台程序代码实现，并没有真正实现访问数据库。我这里通过建立一个ASP.NET网站，实现访问Access与SQL Server数据库。主要参考《大话设计模式》

具体步骤代码如下：

1、 分别在Access和SQL Server建立数据库DaHua与数据库表User(ID,Name)，Department（ID,DepartName）

2、 启动Visual Studio 2005/2008新建网站

3、 到web.config添加数据库连接

4、 在网站解决方案右键新建类库ClassLibrary1，新建类文件，包 括：

AbstractUser抽象类，SqlserverUser类，AccessUser类

AbstractDepartment抽象类，SqlserverDepartment类，AccessDepartment 类

DataAccess类

生成dll

5、到项目添加引用，项目-右键-添加引用-项目-ClassLibrary1

6、前台代码：添加一个GridView控件，三个Button控件，2个TextBox控件

用于查询表User和Department表内容，插入User表数据

 

 

using System;

using System.Configuration;

using System.Data;

using System.Linq;

using System.Web;

using System.Xml.Linq;

using System.Data.SqlClient;

using System.Data.OleDb;

using System.Reflection;

 

namespace ClassLibrary1

{

    /// <summary>

    ///AbstractUser抽象类

    /// </summary>

    public abstract class AbstractUser

    {

        public abstract DataSet GetUser();

        public abstract void InsertUser(string userID, string userName);

    }

 

    /// <summary>

    /// SqlserverUser类

    /// </summary>

    public class SqlserverUser : AbstractUser

    {

        string constr = ConfigurationManager.ConnectionStrings["constrSQLDahua"].ConnectionString;

 

        public override DataSet GetUser()

        {

            SqlConnection conn = new SqlConnection(constr);

            if (conn.State == ConnectionState.Closed)

                conn.Open();

 

            SqlCommand cmd = new SqlCommand("select * from [User]", conn);

            SqlDataAdapter sda = new SqlDataAdapter();

            sda.SelectCommand = cmd;

            DataSet ds = new DataSet();

            sda.Fill(ds);

            return ds;

        }

 

        public override void InsertUser(string userID, string userName)

        {

            SqlConnection conn = new SqlConnection(constr);

            if (conn.State == ConnectionState.Closed)

                conn.Open();

            SqlCommand cmd = new SqlCommand();

            cmd.Connection = conn;

            cmd.CommandText = "insert into [User] values('" + Int32.Parse(userID) + "','" + userName + "') ";

            cmd.ExecuteNonQuery();

            conn.Close();

 

        }

    }

 

    /// <summary>

    /// AccessUser类

    /// </summary>

    public class AccessUser : AbstractUser

    {

        string constr = ConfigurationManager.ConnectionStrings["constrAccessDaHua"].ConnectionString;

 

        public override DataSet GetUser()

        {

            OleDbConnection conn = new OleDbConnection(constr);

            if (conn.State == ConnectionState.Closed)

                conn.Open();

 

            OleDbCommand cmd = new OleDbCommand("select * from [User]", conn);

            OleDbDataAdapter sda = new OleDbDataAdapter();

            sda.SelectCommand = cmd;

            DataSet ds = new DataSet();

            sda.Fill(ds);

            return ds;

        }

 

        public override void InsertUser(string userID, string userName)

        {

            OleDbConnection conn = new OleDbConnection(constr);

            if (conn.State == ConnectionState.Closed)

                conn.Open();

            OleDbCommand cmd = new OleDbCommand();

            cmd.Connection = conn;

            cmd.CommandText = "insert into [User] values('" + Int32.Parse(userID) + "','" + userName + "') ";

            cmd.ExecuteNonQuery();

            conn.Close();

        }

}

 

/// <summary>

    ///AbstractDepartment抽象类

    /// </summary>

    public abstract class AbstractDepartment

    {

        public abstract DataSet GetDepartment();

        // void InsertDepartment(string depID, string depName);

    }

 

    /// <summary>

    /// SqlserverDepartment类

    /// </summary>

    public class SqlserverDepartment : AbstractDepartment

    {

        string constr = ConfigurationManager.ConnectionStrings["constrSQLDahua"].ConnectionString;

 

        public override DataSet GetDepartment()

        {

            SqlConnection conn = new SqlConnection(constr);

            if (conn.State == ConnectionState.Closed)

                conn.Open();

 

            SqlCommand cmd = new SqlCommand("select * from [Department]", conn);

            SqlDataAdapter sda = new SqlDataAdapter();

            sda.SelectCommand = cmd;

            DataSet ds = new DataSet();

            sda.Fill(ds);

            return ds;

 

        }

    }

 

    /// <summary>

    /// AccessDepartment 类

    /// </summary>

    public class AccessDepartment : AbstractDepartment

    {

        string constr = ConfigurationManager.ConnectionStrings["constrAccessDaHua"].ConnectionString;

 

        public override DataSet GetDepartment()

        {

            OleDbConnection conn = new OleDbConnection(constr);

            if (conn.State == ConnectionState.Closed)

                conn.Open();

 

            OleDbCommand cmd = new OleDbCommand("select * from [Department]", conn);

            OleDbDataAdapter sda = new OleDbDataAdapter();

            sda.SelectCommand = cmd;

            DataSet ds = new DataSet();

            sda.Fill(ds);

            return ds;

        }

 }

 

/// <summary>

    ///DataAccess类

    ///使用反射

    /// </summary>

    public class DataAccess

    {

        private static readonly string AssemblyName = "ClassLibrary1"; //程序集名称

        private static readonly string db = "Sqlserver"; //数据库类型名，要更改访问的数据 库，只需更改这里

 

        public static AbstractUser CreateUser()

        {

            string className = AssemblyName + "." + db + "User"; //命名空间.要实例化的类名

            return (AbstractUser)Assembly.Load(AssemblyName).CreateInstance(className);

        }

 

        public static AbstractDepartment CreateDepartment()

        {

            string className = AssemblyName + "." + db + "Department";

            return (AbstractDepartment)Assembly.Load(AssemblyName).CreateInstance(className);

        }

 }

}

 

前台代码：

public partial class _Default : System.Web.UI.Page 

{

    ClassLibrary1.AbstractUser au = null;

    ClassLibrary1.AbstractDepartment ad = null;

 

    protected void Page_Load(object sender, EventArgs e)

    {

        

       

    }

    protected void Button1_Click(object sender, EventArgs e)

    {

        au =ClassLibrary1.DataAccess.CreateUser();

        DataSet ds = au.GetUser();

        GridView1.DataSource = ds;

        GridView1.DataBind();

 

    }

    protected void Button2_Click(object sender, EventArgs e)

    {        

        string userID = txtID.Text;

        string userName = txtName.Text ;

        au = ClassLibrary1.DataAccess.CreateUser();

        au.InsertUser(userID,userName);

    }

 

    //部门查询

    protected void Button3_Click(object sender, EventArgs e)

    {

        ad = ClassLibrary1.DataAccess.CreateDepartment();

        DataSet ds = ad.GetDepartment();

        GridView1.DataSource = ds;

        GridView1.DataBind();

    }

}

 

转自：http://blog.csdn.net/canhui87/archive/2009/10/20/4704781.aspx