如何在Java中获取System变量值？

public class SystemPropertiesExample {
    public static void main(String[] args) {
        String javaVersion = System.getProperty("java.version");
        String osName = System.getProperty("os.name");
        String osVersion = System.getProperty("os.version");

        System.out.println("Java Version: " + javaVersion);
        System.out.println("Operating System Name: " + osName);
        System.out.println("Operating System Version: " + osVersion);
    }
}