域名解析在Ubuntu64 9.04机器上的Java应用程序中不起作用.所有其他软件都能正确解析DNS

Question

我在Ubuntu64 9.04 PC上安装了许多Java应用程序,但没有一个可以解析域名(也有多个JRE - 其中一些是IBM产品).如果我将域名与其关联的IP地址放在hosts文件中,那么Java应用程序仅适用于这些域.所有其他非Java程序 - 如ping,firefox等 - 在域解析时工作得很好.我试图在java.security文件中禁用DNS缓存 - 对于我的所有JRE - 但这也不起作用.我会很感激帮助你解决这个问题.谢谢!

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更新:我确信我家或办公室里没有代理服务器. - 我感谢你们在这里帮助我.我真的想要使用Linux而不是Windows,因为我正在再次进行Java开发.

jgreenwood@jeg-ubuntu64:~$ cat /etc/resolv.conf
# Generated by NetworkManager
domain hsd1.in.comcast.net.
search hsd1.in.comcast.net.
nameserver 192.168.0.1
jgreenwood@jeg-ubuntu64:~$ env | grep -i proxy
jgreenwood@jeg-ubuntu64:~$ dig google.com

; <<>> DiG 9.5.1-P2 <<>> google.com
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 56845
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;google.com.            IN  A

;; ANSWER SECTION:
google.com.     58  IN  A   74.125.53.100
google.com.     58  IN  A   74.125.45.100
google.com.     58  IN  A   74.125.67.100

;; Query time: 35 msec
;; SERVER: 192.168.0.1#53(192.168.0.1)
;; WHEN: Thu Oct 22 13:37:26 2009
;; MSG SIZE  rcvd: 76

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更新:我在RAD中编写了这个java程序:

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.io.PrintWriter;
import java.io.StringWriter;

public class DomainResolutionTest {

    public static void main(String[] args) {
        if (args.length == 0) args = new String[] { "www.google.com" };

        try {
            InetAddress ip = InetAddress.getByName(args[0]);
            System.out.println(ip.toString());
        }catch (UnknownHostException uhx) {
            System.out.println("ERROR: " + uhx.getMessage() + "\n" + getStackTrace(uhx));
            Throwable cause = uhx.getCause();
            if (cause != null) System.out.println("CAUSE: " + cause.getMessage());
        }

    }

    public static String getStackTrace(Throwable t)
    {
        StringWriter sw = new StringWriter();
        PrintWriter pw = new PrintWriter(sw, true);
        t.printStackTrace(pw);
        pw.flush();
        sw.flush();
        return sw.toString();
    }

}

输出是:

ERROR: www.google.com
java.net.UnknownHostException: www.google.com
    at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
    at java.net.InetAddress$1.lookupAllHostAddr(InetAddress.java:862)
    at java.net.InetAddress.getAddressFromNameService(InetAddress.java:1213)
    at java.net.InetAddress.getAllByName0(InetAddress.java:1166)
    at java.net.InetAddress.getAllByName(InetAddress.java:1096)
    at java.net.InetAddress.getAllByName(InetAddress.java:1032)
    at java.net.InetAddress.getByName(InetAddress.java:982)
    at DomainResolutionTest.main(DomainResolutionTest.java:12)

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从命令行:(相同的结果)

jgreenwood@jeg-ubuntu64:~$ javac DomainResolutionTest.java
jgreenwood@jeg-ubuntu64:~$ java DomainResolutionTest 
ERROR: www.google.com
java.net.UnknownHostException: www.google.com
    at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
    at java.net.InetAddress$1.lookupAllHostAddr(InetAddress.java:849)
    at java.net.InetAddress.getAddressFromNameService(InetAddress.java:1200)
    at java.net.InetAddress.getAllByName0(InetAddress.java:1153)
    at java.net.InetAddress.getAllByName(InetAddress.java:1083)
    at java.net.InetAddress.getAllByName(InetAddress.java:1019)
    at java.net.InetAddress.getByName(InetAddress.java:969)
    at DomainResolutionTest.main(DomainResolutionTest.java:12)
jgreenwood@jeg-ubuntu64:~$ java -version
java version "1.6.0_16"
Java(TM) SE Runtime Environment (build 1.6.0_16-b01)
Java HotSpot(TM) Server VM (build 14.2-b01, mixed mode)
jgreenwood@jeg-ubuntu64:~$ 

Answer 1

再次,感谢这里的人们的指导,我找到了答案.上面的Java程序在我执行以下操作时起作用:

java -Djava.net.preferIPv4Stack=true DomainResolutionTest

细节:

jgreenwood@jeg-ubuntu64:~$ java -Djava.net.preferIPv4Stack=true DomainResolutionTest 
www.google.com/209.85.225.106
jgreenwood@jeg-ubuntu64:~$ java DomainResolutionTest ERROR: www.google.com
java.net.UnknownHostException: www.google.com
    at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
    at java.net.InetAddress$1.lookupAllHostAddr(InetAddress.java:849)
    at java.net.InetAddress.getAddressFromNameService(InetAddress.java:1200)
    at java.net.InetAddress.getAllByName0(InetAddress.java:1153)
    at java.net.InetAddress.getAllByName(InetAddress.java:1083)
    at java.net.InetAddress.getAllByName(InetAddress.java:1019)
    at java.net.InetAddress.getByName(InetAddress.java:969)
    at DomainResolutionTest.main(DomainResolutionTest.java:12)

事实证明,IPv6堆栈中存在一个错误.有几篇帖子让我得出这样的结论:

http://uclue.com/?xq=2127

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=477211

https://answers.launchpad.net/ubuntu/+question/23024

我确定希望每次运行Java应用程序时都不必添加IPv4垃圾.最终解决方案可能在第二个链接 - 缺少包.我们会看到.

Debian Bug报告日志 - #477211 ia32-sun-java6-bin:需要依赖于lib32nss-mdns ...无法解析域名.在系统的其余部分解决很好,没有与其他JDK测试过.从包安装并使用update-java-alternatives进行设置.

DNS适用于我系统上的其他所有内容.在Debian 2.6.23-AMD64上运行.尝试过Lenny软件包和Sid软件包.使用sun-java6-bin按预期工作,使用ia32-sun-java6-bin失败.精氨酸....如果你用strace命中java,你会发现它正在尝试使用libnss_mdns4_minimal.so.2,它可以在包lib32nss-mdns中找到.您应该添加一个依赖项来修复错误.

对于sun-java6-bin也会发生同样的事情 - 这里使用了libnss-mdns.

我的机器上确实缺少包装:

jgreenwood@jeg-ubuntu64:~$ dpkg -L lib32nss-mdns
Package `lib32nss-mdns' is not installed.
Use dpkg --info (= dpkg-deb --info) to examine archive files,
and dpkg --contents (= dpkg-deb --contents) to list their contents.

无论哪种方式,我希望这篇文章可以帮助其他人,因为这是一个重要的PITA.