Properties props = System.getProperties();
Enumeration<?> names = props.propertyNames();
while (names.hasMoreElements()) {
String name = (String) names.nextElement();
System.out.println(name + "=" + System.getProperty(name));
}
System.getProperties() 獲取所有系統屬性鍵值對propertyNames() 返回屬性名枚舉key=value 格式,包含 java.version、os.name、user.dir 等關鍵信息