java - 客户端代码中的套接字连接被拒绝

Question

以下程序导致此问题

编辑:

import java.io.*;
import java.net.*;
public class smtpClient {
    public static void main(String[] args) {
// declaration section:
// smtpClient: our client socket
// os: output stream
// is: input stream
        Socket smtpSocket = null;  
        DataOutputStream os = null;
        DataInputStream is = null;
// Initialization section:
// Try to open a socket on port 25 : step 1
// Try to open input and output streams: step 2
        try {
            smtpSocket = new Socket("192.168.1.2", 1024);
            os = new DataOutputStream(smtpSocket.getOutputStream());
            is = new DataInputStream(smtpSocket.getInputStream());
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host: hostname");
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to: hostname");
        }
// If everything has been initialized then we want to write some data
// to the socket we have opened a connection to on port 25
    if (smtpSocket != null && os != null && is != null) {
            try {
// The capital string before each colon has a special meaning to SMTP
// you may want to read the SMTP specification, RFC1822/3
        os.writeBytes("HELO\n");    
                os.writeBytes("MAIL From: k3is@fundy.csd.unbsj.ca\n");
                os.writeBytes("RCPT To: k3is@fundy.csd.unbsj.ca\n");
                os.writeBytes("DATA\n");
                os.writeBytes("From: k3is@fundy.csd.unbsj.ca\n");
                os.writeBytes("Subject: testing\n");
                os.writeBytes("Hi there\n"); // message body
                os.writeBytes("\n.\n");
        os.writeBytes("QUIT");
// keep on reading from/to the socket till we receive the "Ok" from SMTP,
// once we received that then we want to break.
                String responseLine;
                while ((responseLine = is.readLine()) != null) {
                    System.out.println("Server: " + responseLine);
                    if (responseLine.indexOf("Ok") != -1) {
                      break;
                    }
                }
// clean up:
// close the output stream
// close the input stream
// close the socket
                os.close();
                is.close();
                smtpSocket.close();   
            } catch (UnknownHostException e) {
                System.err.println("Trying to connect to unknown host: " + e);
            } catch (IOException e) {
                System.err.println("IOException:  " + e);
            }
        }
    }           
}

控制台日志:

Couldn't get I/O for the connection to: hostname

我采取的程序来自: http://www.javaworld.com/jw-12-1996/jw-12-sockets.html?page=4

我已经尝试将端口从 25 修改为 1024
我在本地 PC 上运行它，所以我是该系统的管理员，但不确定是否存在任何默认防火墙问题(在 Windows 7 上的 Eclipse 中运行此)

根据您下面的评论:我需要创建一个监听器，这意味着一个服务器套接字，它将监听 smtp 客户端请求

Answer 1

答案是:根据您提供的详细信息，没有正在运行的监听器或指定IP和端口号的机器。

UPD:那么您尝试连接到某个地方时，您必须确保有东西在另一端监听，要么编写您自己的服务器代码，要么使用第 3 方服务器/代码在某个服务器上提供某些服务。您尝试访问的端口号。

为什么您会期望在您提供的地址的计算机上运行邮件服务器？