C#中读取App.config配置文件代码实例

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
 <connectionStrings>
  <add name="conn" connectionString="this is connection string"/>
 </connectionStrings>
 <appSettings>
  <add key="key1" value="value1" />
  <add key="key2" value="value2" />
 </appSettings>
</configuration>

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

namespace AppConfig
{
  class Program
  {
    static void Main(string[] args)
    {
      Console.WriteLine("ConnectionStrings:");
      // ConfigurationManager.ConnectionStrings是一个ConnectionStringSettingsCollection对象
      // 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;
        Console.WriteLine(i.ToString() + ". " + name + " = " + 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;
        Console.WriteLine(name + " = " + connectionString);
      }
      //直接获取conn的值
      Console.WriteLine("\r\nGet the value of the node named \"conn\":");
      Console.WriteLine(ConfigurationManager.ConnectionStrings["conn"].ConnectionString);
      Console.WriteLine("");

      Console.WriteLine("AppSettings:");
      //AppSettings是NameValueConnection类型，使用AllKeys返回一个所有Key组成的字符串数组
      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];
        Console.WriteLine(i.ToString() + ". " + key + " = " + value);
      }
      // 没有NameValuePair这样的对象，所以无法使用foreach来进行循环

      //直接获取key1的值
      Console.WriteLine("\r\nGet the value of the key named \"key1\":");
      Console.WriteLine(ConfigurationManager.AppSettings["key1"]);

      //pause the process
      Console.ReadKey();
    }
  }
}