Web.config详解

* 读取App.config配置文件

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
 <connectionStrings>
  <add name="hxh" connectionString="Server=DESKTOP-OCGH29Q;database=xx;integrated security=true;Connection Timeout=30;" providerName="System.Data.SqlClient" />
 </connectionStrings>
 <appSettings>
  <add key="key1" value="value1" />
  <add key="key2" value="value2" />
 </appSettings>
</configuration>

App.config文件的特点：

　　- 有一个<configuration>...</configuration>节点，所有的配置都在里面；

　　- c#有一个内置的<connectionStrings>节点，用来存放数据库连接字符串；

using System.Configuration;

      // 按数字循环得到一个个ConnectionStringSettings对象
      // 每个ConnectionStringSettings对象有Name和ConnectionString属性
      for (int i = 0; i < ConfigurationManager.ConnectionStrings.Count; i++)
      {
        string name = ConfigurationManager.ConnectionStrings[i].Name;
        string connectionString = ConfigurationManager.ConnectionStrings[i].ConnectionString;
      }

     //也可以如下操作，使用ConnectionStringSettings类型来进行foreach遍历
      foreach (ConnectionStringSettings conn in ConfigurationManager.ConnectionStrings)
      {
        string name = conn.Name;
        string connectionString = conn.ConnectionString;
      }

    //直接获取conn的值
    ConfigurationManager.ConnectionStrings["conn"].ConnectionString；

//AppSettings是NameValueConnection类型，使用AllKeys返回一个所有Key组成的字符串数组；没有NameValuePair这样的对象，所以无法使用foreach来进行循环
string[] keys = ConfigurationManager.AppSettings.AllKeys;
      for (int i = 0; i < keys.Length; i++)
      {
        string key = keys[i];
        //通过Key来索引Value
        string value = ConfigurationManager.AppSettings[key];
      }

//直接获取key的值
ConfigurationManager.AppSettings["key1"]