.net用工厂模式开发多数据库连接类

用工厂模式开发多数据库连接类，是工厂模式最好的应用方式，也是很多初级使用设计模式的程序员都会涉及到的，下面是具体代码：
A、创建一个类库，里面有如下这些类
一、设计一个抽象类

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Configuration;

//工厂模式连接数据库
namespace DBAccess
{
    //数据连接的工厂模式抽象类
    public abstract class DBabstract
    {
        //构造函数
        public DBabstract()
        { 
        }

        //打开一个连接
        public abstract void Open();

        //关闭一个连接
        public abstract void Close();

        //数据读取的公共数
        public abstract void PublicClass(string procname, object[] parmas);

        //执行无返回DataSet的函数
        public abstract string Execsql(string procname, object[] parmas);

        //执行有返回DataSet的函数
        public abstract DataSet ExecSqlReturnDataSet(string tablename, string procname, object[] parmas);

    }
}

二、定义一个Oracle连接类

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.OracleClient;
using System.Configuration;

//工厂模式连接数据库中的ORACLE数据库连接
namespace DBAccess
{
    //数据连接的工厂模式ORACLE连接类
    internal class DBOracle : DBabstract
    {
        private OracleConnection conn = null;  //数据连接
        private OracleCommand cmd = null;      //连接命令

        //构造函数
        public DBOracle(string constring)
        {
            this.conn = new OracleConnection(constring);
        }

        //打开一个连接
        public override void Open()
        {
            if (this.conn != null && this.conn.State == ConnectionState.Closed)
            {
                this.conn.Open();
            }
        }

        //关闭一个连接
        public override void Close()
        {
            if (this.conn != null && this.conn.State == ConnectionState.Open)
            {
                this.conn.Close();
            }
        }

        //数据读取的公共数
        public override void PublicClass(string procname, object[] parmas)
        {
            OracleParameter[] Oracleparmas = (OracleParameter[])parmas;
            this.cmd = new OracleCommand();
            this.cmd.Connection = this.conn;
            this.cmd.CommandType = CommandType.StoredProcedure;
            this.cmd.CommandText = procname;
            if (this.cmd.Parameters.Count > 0)
            {
                this.cmd.Parameters.Clear();
            }
            if (Oracleparmas != null && Oracleparmas.Length > 0)
            {
                foreach (OracleParameter p in Oracleparmas)
                {
                    this.cmd.Parameters.Add(p);
                }
            }
        }

        //执行无返回DataSet的函数
        //<param name="procname">存储过程名</param>
        //<param name="parmas">参数数组</param>
        public override string Execsql(string procname, object[] parmas)
        {
            try
            {
                OracleParameter[] Oracleparmas = (OracleParameter[])parmas;
                this.Open();
                this.PublicClass(procname, Oracleparmas);
                int var = this.cmd.ExecuteNonQuery();
                this.cmd.Parameters.Clear();
                this.Close();
                return Convert.ToString(var);
            }
            catch(Exception ex)
            {
                string e = ex.Message;
                this.Close();
                throw;
            }
        }

        //执行有返回DataSet的函数
        //<param name="tablename">DataSet表名</param>
        //<param name="procname">存储过程名</param>
        //<param name="parmas">参数数组</param>
        public override DataSet ExecSqlReturnDataSet(string tablename, string procname, object[] parmas)
        {
            try
            {
                OracleParameter[] Oracleparmas = (OracleParameter[])parmas;
                this.PublicClass(procname, Oracleparmas);
                DataSet ds = new DataSet();
                using (OracleDataAdapter da = new OracleDataAdapter())
                {
                    da.SelectCommand = this.cmd;
                    da.Fill(ds, tablename);
                }
                return ds;

            }
            catch (Exception ex)
            {
                string e = ex.Message;
                throw;
            }
        }
    }
}

三、定义一个SQLSERVER连接类

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

//工厂模式连接数据库中的SQLSERVER数据库连接
namespace DBAccess
{
    //数据连接的工厂模式SQLSERVER连接类
    internal class DBMSSOLServer : DBabstract
    {
        private SqlConnection conn = null;
        private SqlCommand cmd = null;

        //构造函数
        public DBMSSOLServer(string constring)
        {
            this.conn = new SqlConnection(constring);
        }

        //打开一个连接
        public override void Open()
        {
            if (this.conn != null && this.conn.State == ConnectionState.Closed)
            {
                this.conn.Open();
            }
        }

        //关闭一个连接
        public override void Close()
        {
            if (this.conn != null && this.conn.State == ConnectionState.Open)
            {
                this.conn.Close();
            }
        }

        //数据读取的公共数
        public override void PublicClass(string procname, object[] parmas)
        {
            SqlParameter[] SQLparmas = (SqlParameter[])parmas;
            this.cmd = new SqlCommand();
            this.cmd.Connection = this.conn;
            this.cmd.CommandType = CommandType.StoredProcedure;
            this.cmd.CommandText = procname;
            if (this.cmd.Parameters.Count > 0)
            {
                this.cmd.Parameters.Clear();
            }
            if(SQLparmas != null && SQLparmas.Length > 0 )
            {
                foreach (SqlParameter p in SQLparmas)
                {
                    this.cmd.Parameters.Add(p);
                }
            }
        }

        //执行无返回DataSet的函数
        public override string Execsql(string procname, object[] parmas)
        {
            try
            {
                SqlParameter[] SQLparmas = (SqlParameter[])parmas;
                this.Open();
                this.PublicClass(procname, SQLparmas);
                int var = this.cmd.ExecuteNonQuery();
                this.cmd.Parameters.Clear();
                this.Close();
                return Convert.ToString(var);
            }
            catch (Exception ex)
            {
                string e = ex.Message;
                this.Close();
                throw;
            }
        }

        //执行有返回DataSet的函数
        public override DataSet ExecSqlReturnDataSet(string tablename, string procname, object[] parmas)
        {
            try
            {
                SqlParameter[] SQLparmas = (SqlParameter[])parmas;
                this.PublicClass(procname, SQLparmas);
                DataSet ds = new DataSet();
                using (SqlDataAdapter da = new SqlDataAdapter())
                {
                    da.SelectCommand = this.cmd;
                    da.Fill(ds, tablename);
                }
                return ds;

            }
            catch (Exception ex)
            {
                string e = ex.Message;
                throw;
            }
        }
    }
}

四、创建工厂

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;

//工厂类,数据连接类生成器
namespace DBAccess
{
    public class FactoryClass
    {
        //数据库连接工厂生成器
        //<param name="constring">数据库连接字符串</param>
        public DBabstract GetDB(string constring,string MyDBType)
        {
            if (MyDBType == "Oracle")
            {
                return new DBOracle(constring);
            }
            else if (MyDBType == "MSSQLSERVER")
            {
                return new DBMSSOLServer(constring);
            }
            else if (MyDBType == "ACCESS")
            {
                return new DBMSAccess(constring);
            }
            else
            {
                return null;
            }
        }
    }
}

B、生成解决方案，产生DLL
C、在另外的工程中引用上面产生的DLL
D、使用DLL连接数据库，输入数据

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.OracleClient;

namespace FeatureInfo
{
    public partial class frmRead : Form
    {
        public frmRead()
        {
            InitializeComponent();
        }

        private DBAccess.FactoryClass fac = null;
        private DBAccess.DBabstract dba = null;

        private void frmRead_Load(object sender, EventArgs e)
        {
            fac = new DBAccess.FactoryClass();

            dba = fac.GetDB(System.Configuration.ConfigurationSettings.AppSettings["Oracle"], "Oracle");
        }

        private void GetClient(MapXLib.Feature ftr)   //因是针对MapX开发，所以有这个参数
        {
            MapXLib.Feature fftr = ftr;                   //定义一个MapX图元对象
            string ftrid = fftr.KeyValue;                   //取值
            map.Layers[this.layername].KeyField = "EquipID";
            MapXLib.Feature eftr = ftr;
            string eqid = eftr.KeyValue;
            map.Layers[this.layername].KeyField = "ShortName";
            MapXLib.Feature sftr = ftr;
            string shortname = sftr.KeyValue;
            map.Layers[this.layername].KeyField = "FtrID";

            //创建OracleParameter数组
            OracleParameter[] parmas = new OracleParameter[3] {
                        new OracleParameter("nftr",OracleType.VarChar,13),
                        new OracleParameter("neqid",OracleType.VarChar,50),
                        new OracleParameter("nshortname",OracleType.VarChar,14)
                    };
            if (ftrid != null)
            {
                parmas[0].Value = ftrid;
            }
            else
            {
                parmas[0].Value = DBNull.Value;
            }
            if (eqid != null)
            {
                parmas[1].Value = eqid;
            }
            else
            {
                parmas[1].Value = DBNull.Value;
            }
            if (shortname != null)
            {
                parmas[2].Value = shortname;
            }
            else
            {
                parmas[2].Value = DBNull.Value;
            }

            string t = dba.Execsql("pro_insertClient", (object[])parmas);  
//执行输入操作，将OracleParameter数组强制转换成Object数组做为参数传入函数
        }
    }
}