JavaWeb的邮件发送

采用了多线程的方式来发送
主要是以qq邮箱为例来写的，当然你需要生成qq的授权码
主要用到两个协议：
smtp：发送
pop3：接受

qq授权码如何生成

邮件发送需要依赖两个.jar包，分别是 activation-1.1.1.jar 和 mail-1.4.7.jar 这两个是我用的，当然你也可以去maven上下载

两个jar的网盘链接：https://pan.baidu.com/s/1N6GX1vEYlgh5Wa-w0UUj8g
提取码：6qas

邮件发送实体类

package com.zkw.untils;

//网站的3s原则
//多线程是为了优化用户的体验
import com.zkw.pojo.User;
import com.sun.mail.util.MailSSLSocketFactory;

import javax.activation.DataHandler;
import javax.activation.FileDataSource;
import javax.mail.*;
import javax.mail.internet.*;
import java.util.Properties;

public class SendMailThread extends Thread {
    private User user;

    //设置用于给用户发送邮件的用户名
    private String fromMail = "发送者的邮箱@qq.com";

    //邮箱的授权码
    private String emailPwd = "授权码";

    //发送邮件的服务器地址
    private String host = "smtp.qq.com";

    public SendMailThread(User user) {
        this.user = user;
    }

    @Override
    public void run() {
        try{
            Properties prop = new Properties();
            prop.setProperty("mail.host",host);//设置qq邮件服务器
            prop.setProperty("mail.transport.protocol","smtp");//邮件发送协议
            prop.setProperty("mail.smtp.auth","true");//需要验证用户名密码

            //关于QQ邮箱，换需要设置SSL加密（QQ邮箱特有的）
           MailSSLSocketFactory sf = new MailSSLSocketFactory();
           sf.setTrustAllHosts(true);
           prop.put("mail.smtp.ssl.enable","true");
           prop.put("mail.smtp.ssl.socketFactory",sf);

            //1.创建定义整个应用程序所需要的环境信息的session对象

            //qq特有的
            Session session = Session.getDefaultInstance(prop, new Authenticator() {
                @Override
                protected PasswordAuthentication getPasswordAuthentication() {
                    //发件人的用户名和授权码
                    return new PasswordAuthentication(fromMail,emailPwd);
                }
            });

            //开启session的debug模式，这样可以查看到程序发送的Email的运行状态
            session.setDebug(true);

            //2.通过session得到transport对象
            Transport ts = session.getTransport();

            //3.使用邮件的用户名和授权码连接上邮件服务器
            ts.connect(host,fromMail,emailPwd);

            //4.创建邮件对象
            //注意需要传递Session
            MimeMessage mimeMessage = imageMail(session,user,fromMail);

            //5.发送邮件
            ts.sendMessage(mimeMessage,mimeMessage.getAllRecipients());

            //6.关闭连接
            ts.close();
        }catch (Exception e){
            e.getMessage();
        }

    }
    public static MimeMessage imageMail(Session session,User user,String fromMail) throws Exception {

        //消息的固定信息
        MimeMessage mimeMessage = new MimeMessage(session);

        //邮件发送人
        mimeMessage.setFrom(new InternetAddress(fromMail));

        //邮件接收人
        mimeMessage.setRecipient(Message.RecipientType.TO,new InternetAddress(user.getEmailName()));

        //设置主题
        mimeMessage.setSubject("欢迎来到112青训课堂");

        /*
        编写邮件内容
        1.图片
        2.附件
        3.文本
         */

        //图片
        MimeBodyPart body1 = new MimeBodyPart();
        body1.setDataHandler(new DataHandler(new FileDataSource("C:\\Users\\10404\\Desktop\\123.png")));
        body1.setContentID("zkw.png");//设置图片的ID

        //文本
        MimeBodyPart body2 = new MimeBodyPart();
        body2.setContent("请注意，我不是广告<img src='cid:zkw.png'/>","text/html;charset=utf-8");

        //附件
        MimeBodyPart body3 = new MimeBodyPart();
        body3.setDataHandler(new DataHandler(new FileDataSource("C:\\Users\\10404\\Desktop\\12345.docx")));
        body3.setFileName("log4j.docx");//附件设置名字

        MimeBodyPart body4 = new MimeBodyPart();
        body4.setDataHandler(new DataHandler(new FileDataSource("C:\\Users\\10404\\Desktop\\123.txt")));
        body4.setFileName("log4j.txt");

        //拼接邮件正文内容
        MimeMultipart multipart1 = new MimeMultipart();
        multipart1.addBodyPart(body1);
        multipart1.addBodyPart(body2);
        multipart1.setSubType("related");//1.文本和图片内嵌成功

        //将拼接好的正文内容设置成主题
        MimeBodyPart contentText = new MimeBodyPart();
        contentText.setContent(multipart1);

        //拼接附件
        MimeMultipart allFile = new MimeMultipart();
        allFile.addBodyPart(body3);//附件
        allFile.addBodyPart(body4);//附件
        allFile.addBodyPart(contentText);//正文
        allFile.setSubType("mixed");//正文和附件都存在邮件中，所有类型设置为mixes

        //放到Message消息中
        mimeMessage.setContent(allFile);
        mimeMessage.saveChanges();//保存修改

        return mimeMessage;
    }
}

Servlet实体类

package com.zkw.servlet;

import com.zkw.pojo.User;
import com.zkw.untils.SendMailThread;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class MailServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        String emailName = req.getParameter("emailName");

        User user = new User();
        user.setUsername(username);
        user.setEmailName(emailName);

        //多线程启动邮件送
        new SendMailThread(user).start();

        req.setAttribute("massage","亲爱的用户："+username+"。"+"你在XXX网站上注册的账号为："+username+",密码为："+password+",请妥善保管。");
        req.getRequestDispatcher("info.jsp").forward(req,resp);
    }
}

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
  <head>
    <title>email</title>
  </head>
  <body>

  <form action="${pageContext.request.contextPath}/email.do" method="post">

    <p>用&nbsp;&nbsp;户&nbsp;&nbsp;名：<input type="text" name="username"></p>
    <p>密&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;码：<input type="password" name="password"></p>
    <p>邮&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp箱：<input type="text" name="emailName"></p>
    <p><input type="submit" value="注册"></p>
  </form>

  </body>
</html>

info.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<head>
    <title>Title</title>
</head>
<body>

<h1>XXX网站温馨提示我们已经给你发了一份邮件，因为网络原因你收到的邮件可能会有延迟，请注意查收。</h1>
${massage}

</body>
</html>

User类

package com.zkw.pojo;

public class User {
    private String username;
    private String password;
    private String emailName;

    public User() {
    }

    public User(String username, String password, String emailName) {
        this.username = username;
        this.password = password;
        this.emailName = emailName;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getEmailName() {
        return emailName;
    }

    public void setEmailName(String emailName) {
        this.emailName = emailName;
    }

    @Override
    public String toString() {
        return "user{" +
                "username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", emailName='" + emailName + '\'' +
                '}';
    }
}

整体的运行效果如下

如果你直接拿着这个代码去跑可能会出错，而且还是一个500的错误。
错误如下

原因也很简单，就是tomcat找不到这两个jar，只需要把这两个jar拷贝一份放到tomcat的lib目录就可以了。