System类

String javaVersion = System.getProperty("java.version");

System.out.println("java的version:" + javaVersion);    //java的version:1.8.0_271

String javaHome = System.getProperty("java.home");

System.out.println("java的home:" + javaHome);    //jre的路径****

String osName = System.getProperty("os.name");

System.out.println("os的name:" + osName);    //os的name:Mac OS X

String osVersion = System.getProperty("os.version");

System.out.println("os的version:" + osVersion);    //os的version:10.16

String userName = System.getProperty("user.name");

System.out.println("user的name:" + userName);    //user的name:blackdob

String userHome = System.getProperty("user.home");

System.out.println("user的home:" + userHome);    //user的home:/Users/blackdob

String userDir = System.getProperty("user.dir");

System.out.println("user的dir:" + userDir);    //user的dir路径****