自己用DOS写的。通过修改注册表来修改环境变量的程序。有三个文件，addenv.bat 用来添加环境变量、setenv.bat用来设置环境变量、delenv.bat用来删除环境变量-Own use DOS writes. Modify the registry to modify the program　s environment variables. There are three documents, addenv.bat to add environment variables, setenv.bat to set environment variables, delenv.bat to remove the environment variable