Question

这是我从Java Complete Reference: 7th Edition获得的一个程序。稍作修改：

import java.net.*;
import java.io.*;

public class WhoIs {
    public static void main(String[] args) throws Exception{
        Socket s = new Socket("internic.net",43);

        OutputStream os = s.getOutputStream();
        String domain = "facebook.com"+"\n";
        byte[] stringToByte = domain.getBytes();
        os.write(stringToByte);

        InputStream is = s.getInputStream();
        InputStreamReader reader = new InputStreamReader(is);
        BufferedReader buf = new BufferedReader(reader);

        String temp;
        while((temp=buf.readLine())!="\n"){
            System.out.println(temp);
        }
    }
}

它只是联系internic.net并获取有关Facebook的信息。但是，套接字将无法连接。我得到如下例外：

Exception in thread "main" java.net.ConnectException: Connection refused: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.<init>(Unknown Source)
    at java.net.Socket.<init>(Unknown Source)
    at javacomplete.WhoIs.main(WhoIs.java:8)

所有内容与中的内容完全相同，只有读取数据。我使用了BufferedReader，而本书使用InputStream来读取单个字符。

帮助！为什么不连接？

Answer 1

正确的主机名是whois.internic.net而不是internic.net：

$ telnet internic.net 43
Trying 192.0.43.9...
telnet: connect to address 192.0.43.9: Connection refused
Trying 2001:500:88:200::9...
telnet: connect to address 2001:500:88:200::9: No route to host
telnet: Unable to connect to remote host

$ telnet whois.internic.net 43
Trying 199.7.56.74...
Connected to whois.internic.net.
Escape character is '^]'.

Answer 2

从“拒绝连接”错误中可以清楚地看到，internic.net端口43上没有运行WHOIS服务器。

您想联系哪个WHOIS服务器？大多数域名注册商运行WHOIS服务器，许多ccTLD运营商也运行一个（例如whois.cira.ca ccTLK ca），所有RIR（ARIN，RIPE等）运行一个， gTLD注册管理机构等whois.internic.net有一个等等......

创建一个使用whois的套接字

2 个答案: