System.out.println(System.getenv("JAVA_HOME"));

System.out.println(System.getenv("Path"));

System.out.println(System.getenv("PATH"));//不区分大小写

System.out.println(System.getenv("Tmp"));  

System.out.println("-------------------------------------");

System.out.println(System.getProperty("os.name"));

System.out.println(System.getProperty("OS.NAME"));//区分大小写

System.out.println(System.getProperty("temp"));

System.out.println(System.getProperties());