获取系统属性值

public static void main(String[] args) {

    Properties properties = System.getProperties();
    Set<String> keys = properties.stringPropertyNames();
    Object[] objects = keys.toArray();
    for (int i = 0; i <objects.length ; i++) {

        String key=(String) objects[i];
        String value = properties.getProperty(key);
        System.out.println(key+"===="+value);


    }
    String javaHome = properties.getProperty("java.home");
    System.out.println("java_home目录是  "+javaHome);

    String osName = properties.getProperty("os.name");
    String osVersion = properties.getProperty("os.version");
    System.out.println("系统版本："+osName+" "+osVersion+" 版 ");



public static void main(String[] args) {

    Properties properties = System.getProperties();
    Set<String> keys = properties.stringPropertyNames();

    for(String key:keys){
        String value = properties.getProperty(key);
        System.out.println(key+"--------="+value);

    }
    String javaHome = properties.getProperty("java.home");
    System.out.println("java_home目录是  "+javaHome);

    String osname = properties.getProperty("os.name");
    String osVer = properties.getProperty("os.version");
    System.out.println("系统版本："+osname+" "+osVer+" 版 ");


}