Java 获取本机的ip和主机名

public class SystemProperties {    public static void main(String [] args){          InetAddress netAddress = getInetAddress();          System.out.println("host ip:" + getHostIp(netAddress));          System.out.println("host name:" + getHostName(netAddress));          Properties properties = System.getProperties();          Set<String> set = properties.stringPropertyNames();         //获取java虚拟机和系统的信息。          for(String name : set){              System.out.println(name + ":" + properties.getProperty(name));          }      }      public static InetAddress getInetAddress(){          try{              return InetAddress.getLocalHost();          }catch(UnknownHostException e){              System.out.println("unknown host!");          }          return null;      }      public static String getHostIp(InetAddress netAddress){          if(null == netAddress){              return null;          }   //get the ip address          return ip;      }      public static String getHostName(InetAddress netAddress){          if(null == netAddress){              return null;          }          String name = netAddress.getHostName();  //get the host address          return name;      }  }