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[英]Java Sockets over the Internet: ConnectException (operation timed out)
[英]ConnectException: operation timed out
我有以下类打开套接字连接来查询WHOIS服务器。 不幸的是,每次我运行它(例如java WHOIS google.com)时,它总是抛出异常:
Contacting the WHOIS server for 'google.com' at whois.internic.net:43
Exception in thread "main" java.net.ConnectException: Operation timed out
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:432)
at java.net.Socket.connect(Socket.java:529)
at java.net.Socket.connect(Socket.java:478)
at java.net.Socket.<init>(Socket.java:375)
at java.net.Socket.<init>(Socket.java:189)
at WHOIS.performWhoisQuery(WHOIS.java:11)
at WHOIS.main(WHOIS.java:28)
问题似乎是连接超时,我尝试将超时设置为更长的值(例如5000)并且它不起作用。 它与代理和/或防火墙有关吗? 我整天都陷入困境。
public class WHOIS {
public static void performWhoisQuery(String host, int port, String query) throws Exception {
System.out.println(" Contacting the WHOIS server for '" + query + "' at " + host + ":" + port);
Socket socket = new Socket(host, port);
InputStreamReader isr = new InputStreamReader(socket.getInputStream());
BufferedReader br = new BufferedReader(isr);
PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
out.println(query);
String aLine = "";
while ((aLine = br.readLine()) != null) {
System.out.println(aLine);
}
}
public static void main(String[] args) throws Exception {
String domainNameToCheck = args[0];
performWhoisQuery("whois.internic.net", 43, domainNameToCheck);
}
}
检查是否是防火墙问题的一种简单方法是使用telnet
从同一台计算机连接到目标主机/端口。
例如,在我的Linux机器上:
aix@aix:~$ telnet whois.internic.net 43 Trying 199.7.57.74... Connected to whois.internic.net. Escape character is '^]'.
如果您能够连接,那么问题在于您的Java程序。 否则问题出在其他地方(防火墙等)。
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