求运行中打印JVM系统属性的java代码

Question

//package com.cn-java;import java.lang.System;
import java.util.Properties;
import java.util.Hashtable;
import java.util.Enumeration;public class SystemInfo{
        //存放JVM获得的系统属性
        static private Properties _property;  
        
        //Main function
        public static void main(String[] args){
                getSystemProperty();
                
                Hashtable hashKey;
                hashKey=new Hashtable();
                //将系统信息的关键字和标题放到hashtable
                hashKey.put("java.home",                        "Java安装目录          ");
                hashKey.put("java.class.path",                  "装载类的路径          ");
                hashKey.put("java.specification.version",       "Java API 规范的版本   ");
                hashKey.put("java.specification.vendor",        "Java API 规范的厂商   ");
                hashKey.put("java.specification.name",          "Java API 规范的名称   ");
                hashKey.put("java.version",                     "Java API 实现的版本   ");
                hashKey.put("java.vendor",                      "Java API 实现的厂商   ");
                hashKey.put("java.vendor.url",                  "Java API 规范厂商的URL");
                hashKey.put("java.vm.specification.version",    "Java虚拟机规范的版本  ");
                hashKey.put("java.vm.specification.vendor",     "Java虚拟机规范的厂商  ");
                hashKey.put("java.vm.specification.name",       "Java虚拟机规范的名称  ");
                hashKey.put("java.vm.version",                  "Java虚拟机实现的版本  ");
                hashKey.put("java.vm.vendor",                   "Java虚拟机实现的厂商  ");
                hashKey.put("java.vm.name",                     "Java虚拟机实现的名称  ");
                hashKey.put("java.class.version",               "Java类文件格式的版本  ");
                hashKey.put("os.name",                          "主机操作系统的名称    ");
                hashKey.put("os.arch",                          "主机操作系统的体系结构");
                hashKey.put("os.version",                       "主机操作系统的版本    ");
                hashKey.put("file.separator",                   "平台目录的分隔符      ");
                hashKey.put("path.separator",                   "平台路径的分隔符      ");
                hashKey.put("line.separator",                   "平台文本行的分隔符    ");
                hashKey.put("user.name",                        "当前用户的帐户名称    ");
                hashKey.put("user.home",                        "当前用户的根目录      ");
                hashKey.put("user.dir",                         "当前工作目录          ");                
                Enumeration enum;
                String propertyKey;
                enum=hashKey.keys();
                while(enum.hasMoreElements()){
                        propertyKey=(String)enum.nextElement();                         System.out.println((String)hashKey.get(propertyKey)
+":"+_property.getProperty(propertyKey));
                }                                                
        }
        /**
         * 获得系统属性列表
         * @return Properties
        */
        static public Properties getSystemProperty(){
                _property=System.getProperties();
                return _property;
        }
}