<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <connectionStrings>
    <add name="strCon" connectionString="server=127.0.0.1;user id=sa; password=csw; database=testDB;"/>
  </connectionStrings>
  <appSettings>
    <add key="ConnectionString" value="server=127.0.0.1;user id=sa; password=csw; database=testDB;"/>
    <add key="ConStringEncrypt" value="true"/>
  </appSettings>
</configuration>

方法一：         string connStr= System.Configuration.ConfigurationManager.ConnectionStrings["strCon"].ToString();


方法二：          string connStr= ConfigurationManager.AppSettings["ConnectionString"];