在 Java 中返回 IPv6
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Return IPv6 in Java
提问by Nick
Is there a way in Java to tell it to return IPv6 only? I've tried everything and can't get it to work.
Java 中有没有办法告诉它只返回 IPv6？我已经尝试了一切，但无法正常工作。
try
{
InetAddress inet = InetAddress.getByName(hostName);
boolean status = inet.isReachable(5000);
if (status)
{
System.out.println(inet.getCanonicalHostName() + " Host Reached\t" + java.net.Inet6Address.getByName(hostName).getHostAddress());
}
else
{
System.out.println(inet.getCanonicalHostName() + " Host Unreachable");
}
}
catch (UnknownHostException e)
{
System.err.println("Host does not exists");
}
catch (IOException e)
{
System.err.println("Error in reaching the Host");
}
The line I use to try to return IPv6 only:
我用来尝试仅返回 IPv6 的行：
System.out.println(inet.getCanonicalHostName() + " Host Reached\t" + java.net.Inet6Address.getByName(hostName).getHostAddress());
This keeps returning IPv4. Anyone have any idea of why its doing this?
这会不断返回 IPv4。任何人都知道为什么这样做？
回答by Pr0gr4mm3r
java.net.Inet6Addressdoes not override getByName()
so it will always return the specific IPv4-Address,
unless your parameter itself is in the form of an valid IPv6-Address, in this case this method will return an Inet6Address-Object.
java.net.Inet6Address不会覆盖，getByName()
因此它将始终返回特定的 IPv4 地址，除非您的参数本身采用有效 IPv6 地址的形式，在这种情况下，此方法将返回 Inet6Address 对象。
For example:getByName("stackoverflow.com")--> Inet4AddressgetByName("2001:0db8:85a3:08d3:1319:8a2e:0370:7344")--> Inet6Address
例如：getByName("stackoverflow.com")--> Inet4Address getByName("2001:0db8:85a3:08d3:1319:8a2e:0370:7344")--> Inet6Address
InetAddress.getByName()-Documentation
InetAddress.getByName()-文档
Determines the IP address of a host, given the host's name. The host name can either be a machine name, such as "java.sun.com", or a textual representation of its IP address. If a literal IP address is supplied, only the validity of the address format is checked.
> For host specified in literal IPv6 address, either the form defined in RFC 2732 or the literal IPv6 address format defined in RFC 2373 is accepted.<
根据主机名确定主机的 IP 地址。主机名可以是机器名称，例如“java.sun.com”，也可以是其 IP 地址的文本表示。如果提供了文字 IP 地址，则仅检查地址格式的有效性。
> 对于以文字 IPv6 地址指定的主机，接受 RFC 2732 中定义的格式或 RFC 2373 中定义的文字 IPv6 地址格式。<
So if you want to get an IPv6-Address you need to define it within your parameter, or configure a DNS-Server to return the IPv6-Address instead of the IPv4-Address.
因此，如果您想获得 IPv6 地址，则需要在参数中定义它，或者配置 DNS 服务器以返回 IPv6 地址而不是 IPv4 地址。
Another way to retrieve the IPv6-Address is using InetAddress.getAllByName("www.google.at")which returns all known IP-Addresses of the host.
另一种检索 IPv6 地址的方法是使用InetAddress.getAllByName("www.google.at")它返回主机的所有已知 IP 地址。
For example you can use this method to filter the returned array, which return the first IPv6-Address or nullif the host don't have one:
例如，您可以使用此方法过滤返回的数组，该数组返回第一个 IPv6 地址，或者null如果主机没有：
public Inet6Address getIPv6Addresses(InetAddress[] addresses) {
for (InetAddress addr : addresses) {
if (addr instanceof Inet6Address) {
return (Inet6Address) addr;
}
}
return null;
}
UPDATE:For more functions, especially those affecting DNS-Servers, I recommend using the external library DNSJava, because the plain Java implementation of DNS support is poor.
http://www.dnsjava.org/
更新：对于更多功能，尤其是影响 DNS 服务器的功能，我建议使用外部库 DNSJava，因为 DNS 支持的纯 Java 实现很差。
http://www.dnsjava.org/
Current Code:
当前代码：
public class Ping
{
public void pingHost (String hostName)
{
try
{
InetAddress[] inet = InetAddress.getAllByName(hostName);
String address = this.getIPv4Addresses(inet).getHostAddress();
boolean status = this.getIPv6Addresses(inet).isReachable(5000);
if (status)
{
System.out.println(reverseDns(address) + " Host Reached\t" + this.getIPv6Addresses(inet).getHostAddress());
}
else
{
System.out.println(this.getIPv6Addresses(inet).getCanonicalHostName() + " Host Unreachable");
}
}
catch (UnknownHostException e)
{
System.err.println("Host does not exists");
}
catch (IOException e)
{
System.err.println("Error in reaching the Host");
}
}
public Inet6Address getIPv6Addresses(InetAddress[] addresses)
{
for (InetAddress addr : addresses)
{
if (addr instanceof Inet6Address)
{
return (Inet6Address) addr;
}
}
return null;
}
public Inet4Address getIPv4Addresses(InetAddress[] addresses)
{
for (InetAddress addr : addresses)
{
if (addr instanceof Inet4Address)
{
return (Inet4Address) addr;
}
}
return null;
}
public static String reverseDns(String hostIp) throws IOException
{
Resolver res = new ExtendedResolver();
Name name = ReverseMap.fromAddress(hostIp);
int type = Type.PTR;
int dclass = DClass.IN;
Record rec = Record.newRecord(name, type, dclass);
Message query = Message.newQuery(rec);
Message response = res.send(query);
Record[] answers = response.getSectionArray(Section.ANSWER);
if (answers.length == 0)
return hostIp;
else
return answers[0].rdataToString();
}
}
回答by lanwen
You could try to define JVM_ARGS
您可以尝试定义 JVM_ARGS
-Djava.net.preferIPv4Stack=false -Djava.net.preferIPv6Addresses=true
-Djava.net.preferIPv4Stack=false -Djava.net.preferIPv6Addresses=true
with that props it will prefer IPv6 addr on InetAddress#getByName
有了这个道具，它会更喜欢 IPv6 地址 InetAddress#getByName
More info: https://docs.oracle.com/javase/8/docs/technotes/guides/net/ipv6_guide/
更多信息：https: //docs.oracle.com/javase/8/docs/technotes/guides/net/ipv6_guide/
