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Java 返回最有可能是外部地址的地址。

欢马劈雪

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返回最有可能是外部地址的地址。

实例源码：

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*           GNU GENERAL PUBLIC LICENSE

*              Version 2, June 1991

*          ADDITIONAL REQUIREMENT

* 1. If PeerfactSim.KOM is used for the evaluation in research publications,

* the following should be referenced:

* @techreport{   PWLS07,

*    author = {Konstantin Pussep and Matthias Weinert and Nicolas Liebau and Ralf Steinmetz},

*    title = {Flexible Framework for NAT Traversal in Peer-to-Peer Applications},

*    month = {Nov},

*    year = {2007},

*    institution = {KOM - Multimedia Communications Lab, Technische Universit{\"a}t Darmstadt},

*    address = {Merckstra{\ss}e 25, 64283 Darmstadt, Germany},

*    number = {KOM-TR-2007-06},

* }

//package com.nowjava;//来 自 n o w j a v a . c o m

import java.net.InetAddress;

import java.net.NetworkInterface;

import java.net.SocketException;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Enumeration;

import java.util.Iterator;

public class Main {

public static void main(String[] argv) throws Exception {
    /*
     from nowjava - 时  代  Java 
    */

System.out.println(getMostProbableExternalAddress());

}

/**

* Returns the address which is most likely the external address. The result does not have

* to be valid in the external network, since this method does not check for NAT-environments

* etc.

* @param addresses list of addresses

* @return the address which is most probably the external address

public static InetAddress getMostProbableExternalAddress() {

// get network interfaces

Collection<NetworkInterface> activeIfs = getNetworkInterfaces();

// get non-internal addresses

ArrayList<InetAddress> localAddr = new ArrayList<InetAddress>();

ArrayList<InetAddress> nonLocalAddr = new ArrayList<InetAddress>();

for (NetworkInterface ni : activeIfs) {

Enumeration<InetAddress> addresses = ni.getInetAddresses();

while (addresses.hasMoreElements()) {

InetAddress addr = addresses.nextElement();

if (hasLocalScope(addr))

localAddr.add(addr);

else

nonLocalAddr.add(addr);

}

// have nonlocal addresses? then return the "best"

if (!nonLocalAddr.isEmpty()) {

String removeAddrPrefixes[] = { "5.", "10.", "192." };

for (String s : removeAddrPrefixes) {

InetAddress last = nonLocalAddr.get(0);

if (nonLocalAddr.size() == 1)

return last;

removeAddressesWith(nonLocalAddr, s);

if (nonLocalAddr.size() == 0)

return last;

else if (nonLocalAddr.size() == 1)

return nonLocalAddr.get(0);

}

// we tried to get the right one, but more than one are left.. return first entree

return nonLocalAddr.get(0);

}

// we dont want to return (link-)local addresses, throw exception

throw new IllegalStateException("No external address found!");

}

/**

* Returns all network interfaces of this host.

* @return all network interfaces of this host

public static Collection<NetworkInterface> getNetworkInterfaces() {

// get network interfaces

ArrayList<NetworkInterface> result = new ArrayList<NetworkInterface>();

Enumeration<NetworkInterface> ifs = null;

try {

ifs = NetworkInterface.getNetworkInterfaces();

} catch (SocketException e1) {

throw new IllegalStateException(

"Could not enumerate network interfaces!");

}

while (ifs.hasMoreElements()) {

result.add(ifs.nextElement());

}

return result;

}

/**

* Returns true when the given address is a local address.

* @param addr address
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编辑于 2020-03-26 09:23:272020-03-26 09:23:27

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