The Java Tutorials have been written for JDK 8.Java教程是为JDK 8编写的。Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.本页中描述的示例和实践没有利用后续版本中引入的改进，并且可能使用不再可用的技术。See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.有关Java SE 9及其后续版本中更新的语言特性的摘要，请参阅Java语言更改。
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.有关所有JDK版本的新功能、增强功能以及已删除或不推荐的选项的信息，请参阅JDK发行说明。
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