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。
The NetworkInterface class has no public constructor. Therefore, you cannot just create a new instance of this class with the new operator. Instead, the following static methods are available so that you can retrieve the interface details from the system: getByInetAddress(), getByName(), and getNetworkInterfaces(). The first two methods are used when you already know the IP address or the name of the particular interface. The third method, getNetworkInterfaces() returns the complete list of interfaces on the machine.
Network interfaces can be hierarchically organized. The NetworkInterface class includes two methods, getParent() and getSubInterfaces(), that are pertinent to a network interface hierarchy. The getParent() method returns the parent NetworkInterface of an interface. If a network interface is a subinterface, getParent() returns a non-null value. The getSubInterfaces() method returns all the subinterfaces of a network interface.
The following example program lists the name of all the network interfaces and subinterfaces (if any exist) on a machine.
import java.io.*;
import java.net.*;
import java.util.*;
import static java.lang.System.out;
public class ListNIFs
{
public static void main(String args[]) throws SocketException {
Enumeration<NetworkInterface> nets = NetworkInterface.getNetworkInterfaces();
for (NetworkInterface netIf : Collections.list(nets)) {
out.printf("Display name: %s\n", netIf.getDisplayName());
out.printf("Name: %s\n", netIf.getName());
displaySubInterfaces(netIf);
out.printf("\n");
}
}
static void displaySubInterfaces(NetworkInterface netIf) throws SocketException {
Enumeration<NetworkInterface> subIfs = netIf.getSubInterfaces();
for (NetworkInterface subIf : Collections.list(subIfs)) {
out.printf("\tSub Interface Display name: %s\n", subIf.getDisplayName());
out.printf("\tSub Interface Name: %s\n", subIf.getName());
}
}
}The following is sample output from the example program:
Display name: bge0
Name: bge0
Sub Interface Display name: bge0:3
Sub Interface Name: bge0:3
Sub Interface Display name: bge0:2
Sub Interface Name: bge0:2
Sub Interface Display name: bge0:1
Sub Interface Name: bge0:1
Display name: lo0
Name: lo0