.NET 读取配置文件中的连接字符串

 using System;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

namespace FirseCase.DAL
{
    /// <summary>
    /// DataBase 的摘要说明  用于连接数据库的类
    /// </summary>
    public class DataBase
    {
        protected string ConnectionString;//连接数据库的字符串
        protected SqlConnection Connection; //数据库连接对象
        public DataBase()
        {
            //
            // TODO: 在此处添加构造函数逻辑
            //
          /// Configuration.Configuration rootWebConfig =
          //  Configuration.WebConfigurationManager.OpenWebConfiguration("/FirstCase");
         //   System.Configuration.ConnectionStringSettings ConnectionString;
        //    ConnectionString =
         //   rootWebConfig.ConnectionStrings.ConnectionStrings["DBConnection"];

            //ConnectionString = ConfigurationManager.ConnectionStrings["DBConnection"].ConnectionString;
          // ConnectionString= ConfigurationManager.ConnectionStrings["DBConnection"].ConnectionString;
            ConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings["DBConnectionString"].ConnectionString;

           // ConnectionString = setting.ConnectionString;

        }
        /// <summary>
        /// 析构函数，关闭数据库
        /// </summary>
        ~DataBase()
        {
            try
            {
                if (Connection != null)
                {
                    Connection.Close();
                }
            }
            catch { }
        }
        /// <summary>
        /// 打开数据库连接
        /// </summary>
        protected void Open()
        {
            if (Connection == null)
            {
                Connection = new SqlConnection(ConnectionString);
            }
            if (Connection.State.Equals(ConnectionState.Closed)) {
                Connection.Open();
            }
          
        }
        /// <summary>
        /// 关闭数据库
        /// </summary>
        public void Close()
        {
            if (Connection != null)
            {
                Connection.Close();
            }
        }
        /// <summary>
        /// 获取数据，返回一个DataSet
        /// </summary>
        /// <param name="sqlString"></param>
        /// <returns></returns>
        public DataSet GetDataSet(string sqlString)
        {
            Open();
            SqlDataAdapter adapter = new SqlDataAdapter(sqlString, Connection);
            DataSet dataSet = new DataSet();
            adapter.Fill(dataSet);
            Close();
            return dataSet;
        }
      
    }
}

 

 

 

 

配置文件：

<connectionStrings>
  <add name="DBConnectionString" connectionString="Data Source=(local);Initial Catalog=sss;Integrated Security=True" providerName="System.Data.SqlClient"/>
 </connectionStrings>