发送JavaMail时发生MailConnectException

我正在尝试从servlet发送JavaMail。servlet的代码如下所示：

package com.lsp.web;

import com.lsp.service.Mailer;
import org.springframework.beans.factory.annotation.Autowired;

import javax.mail.MessagingException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet(name = "contact", urlPatterns = {"/contact"})
public class ContactServlet extends SpringInjectedServlet {
    @Autowired
    private Mailer mailer;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.getRequestDispatcher("contact.jsp").forward(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String customerEmail = req.getParameter("email");
        String subject = req.getParameter("subject");
        String body = req.getParameter("message");

        String error = null;
        String succMess = null;

        try {
            javax.mail.internet.InternetAddress ia = new javax.mail.internet.InternetAddress(customerEmail);
            ia.validate();
            mailer.send(customerEmail, subject, body); //Maler class send method
            req.setAttribute("succMessage", succMess);
            req.getRequestDispatcher("sent.jsp").forward(req, resp);

        } catch (javax.mail.internet.AddressException ae) {
            error = "您指出的邮箱地址不存在";
            req.setAttribute("errorMessage", error);
            req.getRequestDispatcher("contact.jsp").forward(req, resp);
        }
        catch (MessagingException mex) {
            error = "发送失败";
            req.setAttribute("errorMessage", error);
            req.getRequestDispatcher("contact.jsp").forward(req, resp);
        }
    }
}

那么我的邮件类是：

package com.lsp.service;

import org.apache.log4j.Logger;
import org.springframework.stereotype.Component;

import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import java.util.Properties;

@Component
public class Mailer {
    private static final Logger log = Logger.getLogger(Mailer.class);

    public Mailer() {
        log.info("I'm newed.");
    }

    public void send(String from, String subject, String body) {
        String to = "jshao745@gmail.com";
        String host = "localhost";

        Properties properties = System.getProperties();
        properties.setProperty("mail.smtp.host", host);

        Session session = Session.getDefaultInstance(properties);

        try{
            // Create a default MimeMessage object.
            MimeMessage message = new MimeMessage(session);

            // Set From: header field of the header.
            message.setFrom(new InternetAddress(from));

            // Set To: header field of the header.
            message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));

            // Set Subject: header field
            message.setSubject(subject);

            // Send the actual HTML message, as big as you like
            message.setText(body);

            // Send message
            Transport.send(message);
            System.out.println("Sent message successfully....");
        }catch (MessagingException mex) {
            mex.printStackTrace();
        }
    }
}

在点击jsp页面的提交表单上的提交（或发送）按钮后，我得到一个异常，说：

com.sun.mail.util.MailConnectException: Couldn't connect to host, port: localhost, 25; timeout -1;
nested exception is:java.net.SocketException: Network is unreachable: connect

25号端口是从哪里来的？为什么我会遇到这个异常，如何解决它

如果有人能帮助我，我将不胜感激。

---

谢谢。

解决这个问题的方法是：

1.）设置smtp服务，以便会话可以连接到某些内容并将smtp邮件排队。在Windows上很容易使用，只需下载、解压缩并执行run.bat。将有一个服务在localhost:25上运行

2.）使用

getDefaultInstance

设置一些默认属性，而

getInstance

会敦促您创建一组属性，以便客户端可以连接到SMTP服务。看看哪一个更适合你

---

3.）阅读有关SMTP的信息。如果您希望您的代码只使用客户端发送消息，那么您确实需要提高这方面的知识。

我将getDefaultInstance（属性）更改为getInstance（属性），但仍然给了我相同的异常。1）您的问题的答案是：您没有在代码中设置端口，如链接的问题所示。2.）您确定在localhost:25中运行sendmail/apache james/其他smtp服务吗？？？如何检查第二部分？检查清单：1.）是否安装了smtp服务？2）您使用的是什么操作系统？--如果使用Windows，几乎可以肯定您不会这样做，您的测试将永远无法工作；如果是Unix/Linux，请在终端中键入“sendmail-h”以检查它是否可用。不过，我正在运行Tomcat。Tomcat是一个web容器。它不提供smtp中继服务。谢谢。我将继续下载ApacheJames，但我也想要我的TomcatRuuning。