环境变量(Environment Variable)那点事

在Windows编程中，我们可能经常需要用到环境变量。它其实相当于是操作系统级别的一个配置文件。

.NET编程中可以很方便地访问到这些环境变量，下面的代码就演示了这个过程

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;



using System.Collections;



namespace ConsoleApplication1

{

    class Program

    {

        static void Main(string[] args)

        {

            //依次打印三种级别的环境变量



            Console.WriteLine("计算机的环境变量");

            foreach (DictionaryEntry item in Environment.GetEnvironmentVariables(EnvironmentVariableTarget.Machine))

            {

                Console.WriteLine("{0}:{1}",item.Key,item.Value);

            }

            Console.WriteLine();





            Console.WriteLine("用户的环境变量");



            foreach (DictionaryEntry item in Environment.GetEnvironmentVariables(EnvironmentVariableTarget.User))

            {

                Console.WriteLine("{0}:{1}", item.Key, item.Value);

            }

            Console.WriteLine();



            Console.WriteLine("进程的环境变量");



            foreach (DictionaryEntry item in Environment.GetEnvironmentVariables())

            {

                Console.WriteLine("{0}:{1}", item.Key, item.Value);

            }



            //一次性打印所有三种环境变量（直接利用枚举器的遍历



            var targets = Enum.GetNames(typeof(EnvironmentVariableTarget));

            foreach (var target in targets)

            {

                Console.WriteLine("{0}级别的环境变量", target);

                EnvironmentVariableTarget t =(EnvironmentVariableTarget) Enum.Parse(typeof(EnvironmentVariableTarget), target);



                foreach (DictionaryEntry item in Environment.GetEnvironmentVariables(t))

                {

                    Console.WriteLine("{0}:{1}", item.Key, item.Value);

                }



            }





            



        }

    }

}