Java 返回最有可能是外部地址的地址。
返回最有可能是外部地址的地址。
实例源码：
源代码：
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/*3
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* GNU GENERAL PUBLIC LICENSE5
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* Version 2, June 19917
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* 9
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* ADDITIONAL REQUIREMENT11
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* 13
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* 1. If PeerfactSim.KOM is used for the evaluation in research publications, 15
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* the following should be referenced: 17
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* 19
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* @techreport{ PWLS07,21
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* author = {Konstantin Pussep and Matthias Weinert and Nicolas Liebau and Ralf Steinmetz},23
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* title = {Flexible Framework for NAT Traversal in Peer-to-Peer Applications},25
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* month = {Nov},27
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* year = {2007},29
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* institution = {KOM - Multimedia Communications Lab, Technische Universit{\"a}t Darmstadt},31
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* address = {Merckstra{\ss}e 25, 64283 Darmstadt, Germany},33
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* number = {KOM-TR-2007-06},35
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* }37
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*/39
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//package com.nowjava;//来 自 n o w j a v a . c o m41
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import java.net.InetAddress;43
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import java.net.NetworkInterface;46
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import java.net.SocketException;48
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import java.util.ArrayList;50
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import java.util.Collection;52
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import java.util.Enumeration;54
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import java.util.Iterator;56
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public class Main {59
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public static void main(String[] argv) throws Exception {61
/*62
from nowjava - 时 代 Java 63
*/64
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System.out.println(getMostProbableExternalAddress());66
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}68
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/**71
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* Returns the address which is most likely the external address. The result does not have73
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* to be valid in the external network, since this method does not check for NAT-environments75
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* etc.77
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* 79
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* @param addresses list of addresses81
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* @return the address which is most probably the external address83
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*/85
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public static InetAddress getMostProbableExternalAddress() {87
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// get network interfaces89
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Collection<NetworkInterface> activeIfs = getNetworkInterfaces();91
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// get non-internal addresses94
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ArrayList<InetAddress> localAddr = new ArrayList<InetAddress>();96
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ArrayList<InetAddress> nonLocalAddr = new ArrayList<InetAddress>();98
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for (NetworkInterface ni : activeIfs) {100
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Enumeration<InetAddress> addresses = ni.getInetAddresses();102
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while (addresses.hasMoreElements()) {104
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InetAddress addr = addresses.nextElement();106
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if (hasLocalScope(addr))108
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localAddr.add(addr);110
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else112
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nonLocalAddr.add(addr);114
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}116
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}118
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// have nonlocal addresses? then return the "best"121
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if (!nonLocalAddr.isEmpty()) {123
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String removeAddrPrefixes[] = { "5.", "10.", "192." };125
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for (String s : removeAddrPrefixes) {127
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InetAddress last = nonLocalAddr.get(0);129
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if (nonLocalAddr.size() == 1)131
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return last;133
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removeAddressesWith(nonLocalAddr, s);135
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if (nonLocalAddr.size() == 0)137
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return last;139
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else if (nonLocalAddr.size() == 1)141
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return nonLocalAddr.get(0);143
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}145
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// we tried to get the right one, but more than one are left.. return first entree148
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return nonLocalAddr.get(0);150
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}152
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// we dont want to return (link-)local addresses, throw exception155
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throw new IllegalStateException("No external address found!");157
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}159
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/**162
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* Returns all network interfaces of this host.164
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* @return all network interfaces of this host166
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*/168
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public static Collection<NetworkInterface> getNetworkInterfaces() {170
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// get network interfaces172
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ArrayList<NetworkInterface> result = new ArrayList<NetworkInterface>();174
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Enumeration<NetworkInterface> ifs = null;176
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try {178
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ifs = NetworkInterface.getNetworkInterfaces();180
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} catch (SocketException e1) {182
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throw new IllegalStateException(184
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"Could not enumerate network interfaces!");186
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}188
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while (ifs.hasMoreElements()) {190
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result.add(ifs.nextElement());192
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}194
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return result;196
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}198
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/**201
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* Returns true when the given address is a local address.203
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* @param addr address205
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