java邮件发送

2、邮件发送

温馨提示：

下面没使用框架发送邮件，有利于理解源码，以后用SpringBoot比这个简单多了，框架都帮你封装好了

发送邮件前必须要开启下图协议：这里拿QQ邮箱举例，其他的也都在设置里面

下面是封装的发送邮件工具类

在前端接收到邮件然后再后端发送邮件

注意：这里为了用户体验好要领开一个线程，这样就不会等到发送完邮件才跳转了！

servlet：

protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    String username = req.getParameter("username");
    String pwd = req.getParameter("pwd");
    String email = req.getParameter("email");
    User user = new User(username, pwd, email);
    EmailUtil emailUtil = new EmailUtil(user);
    //开启这个线程
    emailUtil.start();
    req.setAttribute("message", user.getUsername()+":h欢迎你的到来！");
    req.getRequestDispatcher("success.jsp").forward(req, resp);
}

package com.bing.utils;

import com.bing.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;

/**
 *    邮件授权码
 *
 * @author zhangbingbing
 * @version 1.0
 * @date 2020/5/13 18:54
 */
public class EmailUtil extends Thread {
    //发送方
    private String from = "1479461930@qq.com";
    //发送方邮箱的用户名
    private String username = "1479461930@qq.com";
    //发送方邮箱的授权码或者密码
    private String pwd = "邮件授权码";
    //发送邮件的服务器地址
    private String host = "smtp.qq.com";

    private User user;
    public EmailUtil(User user) {
        this.user = user;
    }
    @Override
    public void run() {
        try {
            Properties properties = new Properties();
            properties.setProperty("mail.host","smtp.qq.com"); //设置qq服务器发送
            properties.setProperty("mail.transport.protocol","smtp");  //邮件发送协议
            properties.setProperty("mail.smtp.auth","true");   //要验证用户名和密码

            //QQ邮箱还设置了ssl加密，这个有点像MySQL的安全连接，一般大厂才会有
            MailSSLSocketFactory sf = new MailSSLSocketFactory();
            sf.setTrustAllHosts(true);
            properties.put("mail.smtp.ssl.enable","true");
            properties.put("mail.smtp.ssl.socketFactory",sf);


            //以上准备工作完成，下面是使用java发送文件的五个步骤
            //1、创建整个应用程序才需要的session对象，QQ这种大厂才有
            Session session = Session.getDefaultInstance(properties, new Authenticator() {
                @Override
                protected javax.mail.PasswordAuthentication getPasswordAuthentication() {
                    //发送邮件的地址和授权码
                    return new PasswordAuthentication(username, pwd);
                }
            });

            //2、通过session获取transport对象
            Transport transport = session.getTransport();

            session.setDebug(true);
            //3、使用邮件的用户名和授权码连接上服务器, 这三个参数可以根据邮箱的不同进行改变
            transport.connect(host,user.getEmail(),pwd);
            MimeMessage message = getMimeMessage2(session);

            //5、发送邮件
            transport.sendMessage(message,message.getAllRecipients());
            //6、关闭连接
            transport.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    //注册验证时的邮件，没有图片附件什么的
    public MimeMessage getMimeMessage2(Session session) throws Exception {
        //4、创建邮件写邮件，注意传递session
        MimeMessage message = new MimeMessage(session);
        //指明邮件的发送人
        message.setFrom(new InternetAddress(from));
        //邮件的接收人
        message.setRecipient(Message.RecipientType.TO, new InternetAddress(user.getEmail()));
        //邮件的标题
        message.setSubject("注册验证邮件");
        //邮件的内容

        String info = "congratulations，you login successfully!, 您的用户名是：" + user.getUsername() + "密码是：" + user.getPwd();

        //设置到消息中，并保存修改
        message.setContent(info, "text/html;charset=utf-8");
        message.saveChanges();
        return message;
    }


    //发送复杂的邮件，用的少，真正开发邮箱才会用
    public MimeMessage getMimeMessage(Session session) throws Exception {
        //4、创建邮件写邮件，注意传递session
        MimeMessage message = new MimeMessage(session);

        //指明邮件的发送人
        message.setFrom(new InternetAddress(from));
        //邮件的接收人
        message.setRecipient(Message.RecipientType.TO, new InternetAddress(user.getEmail()));
        //邮件的标题
        message.setSubject("我是邮件！");
        //邮件的内容

        //准备图片资源
        MimeBodyPart image = new MimeBodyPart();
        DataHandler dh = new DataHandler(new FileDataSource("图片目录"));
        image.setDataHandler(dh);
        image.setContentID("beautiful.jpg");
        //准备附件资源
        MimeBodyPart affix1 = new MimeBodyPart();
        DataHandler dh1 = new DataHandler(new FileDataSource("附件目录"));
        affix1.setDataHandler(dh1);
        affix1.setFileName("dh1.md");

        MimeBodyPart affix2 = new MimeBodyPart();
        DataHandler dh2 = new DataHandler(new FileDataSource("附件目录"));
        affix2.setDataHandler(dh2);
        affix2.setFileName("dh2.md");
        //准备正文数据
        MimeBodyPart text = new MimeBodyPart();
        text.setContent("这是一封正文加图片<img src='cid:beautiful.jpg'>邮件", "text/html;charset=utf-8");

        //设置数据之间的关系
        MimeMultipart mimeMultipart1 = new MimeMultipart();
        mimeMultipart1.addBodyPart(image);
        mimeMultipart1.addBodyPart(text);
        mimeMultipart1.setSubType("related");

        MimeBodyPart mimeBodyPart1 = new MimeBodyPart();
        mimeBodyPart1.setContent(mimeMultipart1);

        MimeMultipart allFile = new MimeMultipart();
        allFile.addBodyPart(affix1);
        allFile.addBodyPart(affix2);
        allFile.addBodyPart(mimeBodyPart1);

        //设置到消息中，并保存修改
        message.setContent(allFile);
        message.saveChanges();
        return message;
    }


}

以后使用框架慢慢完善！
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