Mail sending

1. Principle

Send mail: SMTP protocol

Receiving mail: POP3 protocol

Simple mail: plain text mail without attachments and pictures

Complex mail: with attachments and pictures

To send mail, you need agreement and support

2. Sending simple mail

package com.wang;

import com.sun.mail.util.MailSSLSocketFactory;

import javax.mail.*;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import java.util.Properties;

//发送一封简单的邮件
public class MailDemo01 {
    public static void main(String[] args) throws Exception {

        Properties prop = new Properties();
        //设置QQ邮件服务器
        prop.setProperty("mail.host","smtp.qq.com");
        //邮件发送协议
        prop.setProperty("mail.transport.protocol","smtp");
        //需要验证用户名和密码
        prop.setProperty("mail.smtp.auth","true");

        //关于QQ邮箱,还要设置SSL加密,加上以下代码即可,其他邮箱不需要
        MailSSLSocketFactory sf = new MailSSLSocketFactory();
        sf.setTrustAllHosts(true);
        prop.put("mail.smtp.ssl.enable","true");
        prop.put("mail.smtp.ssl.socketFactory",sf);

        //使用JavaMail发送邮件的五个步骤

        //1.创建定义整个应用所需的环境信息的Session对象
        //QQ才有,其他邮箱不用!
        Session session = Session.getDefaultInstance(prop,new Authenticator() {
            @Override
            public PasswordAuthentication getpasswordAuthentication() {
                //发送人邮件的用户名,授权码
                return new PasswordAuthentication("715180879@qq.com","授权码");
            }
        });

        //开启Session的Debug模式,这样就可以查看到程序发送Email的运行状态
        session.setDebug(true);

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

        //3.使用邮箱的用户名和授权码连上服务器
        ts.connect("smtp.qq.com","715180879@qq.com","授权码");

        //4.创建邮件:写邮件
        //注意需要传递session
        MimeMessage message = new MimeMessage(session);
        //邮件的发件人
        message.setFrom(new InternetAddress("715180879@qq.com"));

        //指明邮件的 收件人,现在发件人和收件人是一样的,那就是自己给自己发
        message.setRecipient(Message.RecipientType.TO,new InternetAddress("715180879@qq.com"));

        //邮件的标题
        message.setSubject("简单邮件");

        //邮件的文本内容
        message.setContent("Hello!","text/html;charset=UTF-8");

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

        //6.关闭连接
        ts.close();

    }
}

3. Sending complex mail

package com.wang;

import com.sun.mail.util.MailSSLSocketFactory;

import javax.activation.DataHandler;
import javax.activation.FileDataSource;
import javax.mail.*;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import java.util.Properties;

//发送一封复杂的邮件
public class MailDemo02 {
    public static void main(String[] args) throws Exception {

        Properties prop = new Properties();
        //设置QQ邮件服务器
        prop.setProperty("mail.host",new InternetAddress("715180879@qq.com"));

        //邮件的标题
        message.setSubject("复杂邮件");

        //=================================================

        //准备图片数据
        MimeBodyPart image = new MimeBodyPart();
        //图片需要经过数据处理    DataHandler:数据处理
        DataHandler dh = new DataHandler((new FileDataSource("D:\\Java_Web\\功能扩展\\mail-java\\src\\resources\\pic.jpg")));
        //在我们的body中放入这个处理的图片数据
        image.setDataHandler(dh);
        //给图片设置一个ID,我们在后面可以使用!
        image.setContentID("pic.jpg");

        //准备正文数据
        MimeBodyPart text = new MimeBodyPart();
        //cid ==> ContentID
        text.setContent("这是一封邮件正文带图片<img src='cid:pic.jpg'>的邮件","text/html;charset=UTF-8");

        //描述数据关系
        MimeMultipart mm = new MimeMultipart();
        mm.addBodyPart(text);
        mm.addBodyPart(image);
        mm.setSubType("related");

        //设置到消息中,保存修改
        //把最后编辑好的邮件放到消息当中
        message.setContent(mm);
        //保存修改
        message.saveChanges();

        //============================================================

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

        //6.关闭连接
        ts.close();

    }
}

4. Sending of user registration email

package com.wang.pojo;

import java.io.Serializable;

//顺手将其序列化
public class User implements Serializable {

    private String name;
    private String password;
    private String email;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getpassword() {
        return password;
    }

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

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public User(String name,String password,String email) {
        this.name = name;
        this.password = password;
        this.email = email;
    }

    public User() {
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                ",password='" + password + '\'' +
                ",email='" + email + '\'' +
                '}';
    }
}

package com.wang.servlet;

import com.wang.pojo.User;
import com.wang.util.Sendmail;

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 RegisterServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException {

        //接受用户请求,封装成对象
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        String email = req.getParameter("email");

//        System.out.println(username);
//        System.out.println(password);
//        System.out.println(email);

        User user = new User(username,password,email);

        //用户注册成功之后,给用户发送一封邮件
        //我们使用线程来专门发送邮件,防止出现耗时,和网站注册人数过多的情况
        Sendmail sendmail = new Sendmail(user);
        //启动线程:线程启动之后就会执行run方法来发送邮件
        sendmail.start();

        //注册用户
        req.setAttribute("message","注册成功,我们已经发送了一封带了注册信息的电子邮件,请查收!如果网络不稳定,可能会过会儿才能收到!!");
        req.getRequestDispatcher("info.jsp").forward(req,resp);

    }

    @Override
    protected void doPost(HttpServletRequest req,IOException {
        doGet(req,resp);
    }
}

package com.wang.util;


import com.sun.mail.util.MailSSLSocketFactory;
import com.wang.pojo.User;

import javax.mail.*;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import java.util.Properties;

//网站3秒原则:用户体验
//多线程实现用户体验!    (异步处理)
public class Sendmail extends Thread {

    //用于给用户发送邮件的邮箱
    private String from = "715180879@qq.com";
    //邮箱的用户名
    private String username = "715180879@qq.com";
    //邮箱的密码
    private String password = "授权码";
    //发送邮件的服务器地址
    private String host = "smtp.qq.com";

    private User user;
    public Sendmail(User user) {
        this.user = user;
    }

    //丛谢run方法的实现,在run方法中发送邮件给指定的用户
    @Override
    public void run() {
        try {
            Properties prop = new Properties();

            prop.setProperty("mail.host",host);
            //邮件发送协议
            prop.setProperty("mail.transport.protocol","smtp");
            //需要验证用户名和密码
            prop.setProperty("mail.smtp.auth","true");

            //关于QQ邮箱,其他邮箱不需要
            MailSSLSocketFactory sf = new MailSSLSocketFactory();
            sf.setTrustAllHosts(true);
            prop.put("mail.smtp.ssl.enable","true");
            prop.put("mail.smtp.ssl.socketFactory",sf);

            //使用JavaMail发送邮件的五个步骤

            //1.创建定义整个应用所需的环境信息的Session对象
            //QQ才有,其他邮箱不用!
            Session session = Session.getDefaultInstance(prop,new Authenticator() {
                @Override
                public PasswordAuthentication getpasswordAuthentication() {
                    //发送人邮件的用户名,授权码
                    return new PasswordAuthentication(from,password);
                }
            });

            //开启Session的Debug模式,这样就可以查看到程序发送Email的运行状态
            session.setDebug(true);

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

            //3.使用邮箱的用户名和授权码连上服务器
            ts.connect(host,username,password);

            //4.创建邮件:写邮件
            //注意需要传递session
            MimeMessage message = new MimeMessage(session);
            //邮件的发件人
            message.setFrom(new InternetAddress(from));

            //指明邮件的 收件人,现在收件人是从前端接收来的
            message.setRecipient(Message.RecipientType.TO,new InternetAddress(user.getEmail()));

            //邮件的标题
            message.setSubject("用户注册邮件");

            String info = "恭喜注册成功,您的用户名: " + user.getName() + "您的密码: " + user.getpassword() + "请妥善保管,如有问题请联系网站客服!";

            message.setContent(info,"text/html;charset=UTF-8");
            message.saveChanges();

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

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