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Programmatic Access to Network Parameters
Network Interface Parameters
You can access network parameters about a network interface beyond the
name and IP addresses assigned to it
You can discover if a network interface is “up” (that is,
running) with the isUP() method. The following methods
indicate the network interface type:
-
isLoopback() indicates if the network interface is a loopback interface.
-
isPointToPoint() indicates if the interface is a point-to-point interface.
-
isVirtual() indicates if the interface is a virtual interface.
The supportsMulticast() method indicates whether the network interface supports multicasting.
The getHardwareAddress() method returns the network interface's
physical hardware address, usually called MAC address, when it is available. The
getMTU() method returns the Maximum Transmission Unit (MTU), which is
the largest packet size.
The following example expands on the example in
Listing Network Interface Addresses by adding the additional network parameters described on this page:
import java.io.*;
import java.net.*;
import java.util.*;
import static java.lang.System.out;
public class ListNetsEx
{
public static void main(String args[]) throws SocketException {
Enumeration<NetworkInterface> nets = NetworkInterface.getNetworkInterfaces();
for (NetworkInterface netint : Collections.list(nets))
displayInterfaceInformation(netint);
}
static void displayInterfaceInformation(NetworkInterface netint) throws SocketException {
out.printf("Display name: %s\n", netint.getDisplayName());
out.printf("Name: %s\n", netint.getName());
Enumeration<InetAddress> inetAddresses = netint.getInetAddresses();
for (InetAddress inetAddress : Collections.list(inetAddresses)) {
out.printf("InetAddress: %s\n", inetAddress);
}
out.printf("Up? %s\n", netint.isUp());
out.printf("Loopback? %s\n", netint.isLoopback());
out.printf("PointToPoint? %s\n", netint.isPointToPoint());
out.printf("Supports multicast? %s\n", netint.supportsMulticast());
out.printf("Virtual? %s\n", netint.isVirtual());
out.printf("Hardware address: %s\n",
Arrays.toString(netint.getHardwareAddress()));
out.printf("MTU: %s\n", netint.getMTU());
out.printf("\n");
}
}
The following is sample output from the example program:
Display name: bge0
Name: bge0
InetAddress: /fe80:0:0:0:203:baff:fef2:e99d%2
InetAddress: /129.156.225.59
Up? true
Loopback? false
PointToPoint? false
Supports multicast? false
Virtual? false
Hardware address: [0, 3, 4, 5, 6, 7]
MTU: 1500
Display name: lo0
Name: lo0
InetAddress: /0:0:0:0:0:0:0:1%1
InetAddress: /127.0.0.1
Up? true
Loopback? true
PointToPoint? false
Supports multicast? false
Virtual? false
Hardware address: null
MTU: 8232
