需要的jar包

1.mysql驱动包
2.mail.jar包

SMTP和POP3协议概述

SMTP协议称为简单邮件传输协议，是一组用于从原地址到目的地址传送邮件的规则，由它来控制信件的中转方式。SMTP协议属于TCP/IP的协议簇，SMTP是负责邮件服务器之间的寄信的通信协定

POP3协议称为邮局协议版本3,也是TCP/IP协议簇的一员，基于POP3协议的服务器是用来接收信件的。每个Email地址一般只有一个如果想要同时收取多个邮箱的信件，就需要挨个设置每个邮箱的POP3服务器地址

自定义的JavamailSender怎么加入actuator的health检查 javamail是一组_邮件

核心代码实现
#创建数据库表
create database javamail;
use javamail;
create table user(
    id int primary key auto_increment,
    username varchar(30) not null,
    password varchar(30) not null,
    nickname varchar(30) not null,
    email varchar(30) not null,
    state int default 0, #标识是否已经激活 0未激活1已激活
    code varchar(64) not null
);

//创建数据库对应的javabean
public class UserBean{
    private Integer id;
    private String username;
    private String password;
    private String nickname;
    private String email;
    private Integer state;
    private String code;
    //省略setter and getter
}

//数据库操作类UserDao
public class UserDao{
    private Connection conn ;
    //获取数据库连接
    public void getConn(){
        Class.forName("com.mysql.jdbc.Driver");
        String url = "mysql:jdbc://localhost:3306/javamail";
        String rootname = "root";
        String rootpass = "chengxi";
        conn = DriverManager.getConnection(url,rootname,rootpass);
    }

    //注册
    public void regist(UserBean user){

        String sql = "insert into user(username,password,nickname,email,code) values(?,?,?,?,?)";
        PreparedStatement pstmt = conn.preparedCall(sql);
        pstmt.setString(1,user.getUsername());
        pstmt.setString(2,user.getPassword());
        pstmt.setString(3,user.getNickname());
        pstmt.setStirng(4,user.getEmail());
        pstmt.setString(5,user.getCode());
        pstmt.executeUpdate();  
    }

    //激活
    public void activeByCode(String code){

        String sql = "update user set state=1,code=null where code=?";
        PreparedStatement pstmt = conn.preparedCall(sql);
        pstmt.setString(1,code);
        pstmt.executeUpdate();  
    }

    //关闭数据库连接
    public void closeConn(){
        if(conn != null){
            conn.close();
        }
    }
}

//一个工具类，用于获取随机code注册激活码
public class UUIDUtils{
    public static String getUUID(){
        return UUID.randomUUID().toString().replace("-","")+UUID.randomUUID().toString().replace("-","");
    }
}


//index.jsp前端页面实现
<form action="<%=request.getContextPath()%>/regist.do" method="post">
    <tr>
        <td><label for="username">账号</label></td>
        <td><input type="text" name="username" /></td>
    </tr>
    <tr>
        <td><label for="password">密码</label></td>
        <td><input type="text" name="password" /></td>
    </tr>
    <tr>
        <td><label for="nickname">昵称</label></td>
        <td><input type="text" name="nickname" /></td>
    </tr>
    <tr>
        <td><label for="email">邮箱</label></td>
        <td><input type="text" name="email" /></td>
    </tr>
    <tr>
        <td><input type="submit" value="注册" /></td>
        <td><input type="reset" name="重写" /></td>
    </tr>
</form>

//发送邮件的Utils工具类
public class SendMailUitls{

    public static void sendMail(String to,String code){
        //session是mail包下的，因为是本地测试，所以第一个参数直接创建默认的即可
        Session session = Session.getInstance(new Properties(),new Authenticator() {
                @Override
                protected PasswordAuthentication getPasswordAuthentication(){
                    return new PasswordAuthentication("server@store.com", "111");
                }
            });

        //创建邮件对象
        Message message = new MimeMessage(session);
        //设置发件人，这里我创建了一个server@store.com用于发送邮件
        message.setFrom(new InternetAddress("server@store.com"));
        message.setRecipient(RecipientType.TO, new InternetAddress(to));
        message.setSubject("来自个博网的注册激活邮件");
        message.setContent("<a href='http://localhost:8080/RegistMailWeb/active.do'>点我激活</a>","text/html;charset=utf-8");

        //发送邮件
        Transport.send(message);
    }   
}


//regist.doServlet实现
public class RegistServlet extends HttpServlet{
    public void init(){
        super.init();
    }

    public void service(HttpServletRequest request,HttpServletResponse response){
        //获取数据
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String nickname = request.getParameter("nickname");
        String email = request.getParameter("email");

        //封装数据
        UserBean user = new UserBean();
        user.setUsername(username);
        user.setPassword(password);
        user.setNickname(nickname);
        user.setEmail(email);
        user.setCode(UUIDUtils.getUUID());

        //注册
        UserDao dao = new UserDao();
        dao.getConn();
        dao.regist(user);
        dao.closeConn();

        //发送邮件
        SendMailUtils.sendMail(email,user.getCode());
    }

    public void destroy(){
        super.desroy();
    }
}   

//创建active.do Servlet用于激活邮箱
public class ActiveServlet HttpServlet{
    public void init(){
        super.init();
    }

    public void service(HttpServletRequest request,HttpServletResponse response){

        //获取数据
        String code = request.getParameter("code");

        //数据库判断对应code是否存在，（这里就不进行判断了，直接进行比对）state=1&code=null代表激活
        UserDao dao = new UserDao();
        dao.activeByCode(code);

        //重定向success.jsp
        request.getRequestDispatcher("/WEB-INF/success.jsp").forward(request,response);
    }

    public void destroy(){
        super.destroy();
    }
}

//编写成功页面
<html>
    <head>
        <title>成功激活</title>
    </head>
    <body>
        <script>
            window.onload = function(){
                alert("已成功激活");
            };
        </script>
    </body>
</html>

//web.xml配置两个Servlet
<servlet>
    <servlet-name>RegistServlet</servlet-name>
    <servlet-class>com.servlet.RegistServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>RegistServlet</servlet-name>
    <url-pattern>/regist.do</url-pattern>
</servlet-mapping>

<servlet>
    <servlet-name>ActiveServlet</servlet-name>
    <servlet-class>com.servlet.ActiveServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>ActiveServlet</servlet-name>
    <url-pattern>/active.do</url-pattern>

效果

打开tomcat服务器和foxmail邮件服务器，然后进入该web首页，点击注册，可以在foxmail中看到对应的email@store.com邮箱中有一封注册邮箱，点击该邮箱中的链接，就进入了激活页面，然后该注册的账号就激活注册成功了