Java6学习笔记62——显示IP

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.io.IOException;

public class ShowIP {
public static void main(String arg[]) {
InetAddress address;

try {
address = InetAddress.getByName("g.cn");
showAddress(address);
address = InetAddress.getLocalHost();
showAddress(address);
byte a[] = { 127,0,0,1 };
address = InetAddress.getByAddress(a);
showAddress(address);
} catch(UnknownHostException e) {
System.out.println(e);
}

}
static void showAddress(InetAddress address) {
byte a[] = address.getAddress();
System.out.println(address.getHostName() +
": " + (a[0] & 0xFF) + "." + (a[1] & 0xFF) +
"." + (a[2] & 0xFF) + "." + (a[3] & 0xFF));//与0xFF做与运算，把符号位剔除
if(address.isLoopbackAddress())
System.out.println(" (the loopback address)");
try {
if(address.isReachable(30000))
System.out.println(" (is reachable)");
} catch(IOException e) {
}
}
}