java网络编程1-查询Internet地址

//通过dns查询后的结果会缓存起来，成功结果永久缓存，失败结果会缓存10s，经过下面的方法设置成功和失败的缓存时间
// 0为不缓存，-1为永不过时，其它单位为s
Security.setProperty("networkaddress.cache.ttl", "10");
Security.setProperty("networkaddress.cache.negative.ttl", "3");

//若是传入的是ip地址，则不会进行dns查询
InetAddress address=InetAddress.getByName("www.baidu.com");
//InetAddress.getByName()传入ip地址，再调用getHostName()不会由于查询dns失败而异常
System.out.println(address.getHostName());//www.baidu.com
System.out.println(address.getHostAddress());//180.97.33.107
System.out.println(Arrays.toString(address.getAddress()));//[-76, 97, 33, 107]
System.out.println(address.toString());//www.baidu.com/180.97.33.107

//equals()有相同的ip地址则相等；hashCode()根据ip地址计算

//System.out.println(address.equals(address2));
//System.out.println(address.hashCode());

//经过echo端口测试机器是否是能够访问
address.isReachable(1000);

//获取硬件网络口的信息
NetworkInterface inter=NetworkInterface.getByName("eth3");
System.out.println(inter.getDisplayName());
System.out.println(inter.getName());