环境变量(Environment Variable)那点事

阳光穿透心脏的1/2处 2022-04-01 14:27 229阅读 0赞

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);
                    }
    
                }
    
    
                
    
            }
        }
    }