参考文章：http://www.jb51.net/article/78405.htm
本程序是基于上文的改进完成。
开发及运行环境：eclipse jdk1.7 tomcat7
本程序以实现最基本功能为主，所用知识很基础，理解后可自行完善。
程序源码：https://github.com/2016lkaust/javamail

实现思路

实现思路

准备工作

• 开启SMTP服务
  在 QQ 邮箱里的 设置->账户里开启 SMTP 服务

Paste_Image.png

• 注意开启完之后，QQ 邮箱会生成一个授权码，在代码里连接邮箱使用这个授权码而不是原始的邮箱密码，这样可以避免使用明文密码。也可以使用明文密码，但是会有密码泄露的风险。（借用原作者的图吧，省的再截图）
  注
  这里的授权码先记下来，第4步要用到。
  
  Paste_Image.png

程序结构

程序结构

实现步骤

• 1、 建数据库、表
• 2、 User类（实体类）
• 3、 UserDao类（与数据库交互）
• 4、 SendMailUtils类（发送邮件）
• 5、 UUIDUtils（生成随机字符串code）
• 6、 RegistServlet（注册账户）
• 7、 ActiveServlet（激活账户）
• 8、 index.jsp（输入界面）
• 9、 success.jsp（成功界面）

具体实现

1、 建数据库、表

/*
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(30) NOT NULL,
  `password` varchar(30) NOT NULL,
  `nickname` varchar(30) NOT NULL,
  `email` varchar(30) NOT NULL,
  `state` int(11) DEFAULT '0',
  `code` varchar(64) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

2、 User类（实体类）

package com.look.bean;

public class User {
    private Integer id;
    private String username;
    private String password;
    private String nickname;//昵称
    private String email;
    private Integer state;//状态
    private String code;//随机码
    getter and setter...
}

3、 UserDao类（与数据库交互）

package com.look.dao;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import com.look.bean.User;
public class UserDao {
    private static Connection conn;
    // 获取数据库连接
    public  void getConn() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/javamail";
            String rootname = "root";
            String rootpass = "123456";
            conn = DriverManager.getConnection(url, rootname, rootpass);
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    // 注册
    public void regist(User user) {
        try {
            String sql = "insert into user(username,password,nickname,email,code) values(?,?,?,?,?)";
            PreparedStatement pstmt;
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, user.getUsername());
            pstmt.setString(2, user.getPassword());
            pstmt.setString(3, user.getNickname());
            pstmt.setString(4, user.getEmail());
            pstmt.setString(5, user.getCode());
            pstmt.executeUpdate();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    // 激活
    public void activeByCode(String code) {
                //状态标志置为1，code置空
        String sql = "update user set state=1,code=null where code=?";
        PreparedStatement pstmt;
        try {
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, code);
            pstmt.executeUpdate();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    // 关闭数据库连接
    public void closeConn() {
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

注
mysql的账号密码需要修改为自己的账号密码。

4、 SendMailUtils类（发送邮件）

package com.look.util;

import java.security.GeneralSecurityException;
import java.util.Properties;

import javax.mail.Address;
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 com.sun.mail.util.MailSSLSocketFactory;
public class SendMailUtils {
    public static void sendMail(String to, String code)
            throws GeneralSecurityException, MessagingException {
        Properties props = new Properties();
        // 开启debug调试
        // props.setProperty("mail.debug", "true");
        // 发送服务器需要身份验证
        props.setProperty("mail.smtp.auth", "true");
        // 设置邮件服务器主机名
        props.setProperty("mail.host", "smtp.qq.com");
        // 发送邮件协议名称
        props.setProperty("mail.transport.protocol", "smtp");
        MailSSLSocketFactory sf = new MailSSLSocketFactory();
        sf.setTrustAllHosts(true);
        props.put("mail.smtp.ssl.enable", "true");
        props.put("mail.smtp.ssl.socketFactory", sf);
        Session session = Session.getInstance(props);
        Message msg = new MimeMessage(session);
        msg.setSubject("本邮件用于测试");
        // send text to the mail
        // StringBuilder builder = new StringBuilder();
        // builder.append("点击测试<a href='http://loc alhost:8080/ssm/listCategory'>listCategory1</a>");
        // msg.setText(builder.toString());
        msg.setContent(
                "<a href='http://localhost:8080/javamail/ActiveServlet?code="
                        + code + "'>点我激活</a>", "text/html;charset=UTF-8");
        msg.setFrom(new InternetAddress("1478161802@qq.com"));
        Transport transport = session.getTransport();
        transport.connect("smtp.qq.com", "1478161802@qq.com",
                "hsvsqhofljqtjgdi");
        transport.sendMessage(msg, new Address[] { new InternetAddress(to) });
        transport.close();
    }
}

注：
msg.setFrom(new InternetAddress("12345678@qq.com"));和transport.connect("smtp.qq.com", "12345678@qq.com","hsvsqhofljqtjgdi");中的12345678@qq.com需要替换为你自己的qq邮箱，hsvsqhofljqtjgdi要替换为自己的授权码。

5、 UUIDUtils（生成随机字符串code）

package com.look.util;
import java.util.UUID;
public class UUIDUtils {
    public static String getUUID() {
        return UUID.randomUUID().toString().replace("-", "")
                + UUID.randomUUID().toString().replace("-", "");
    }
}

6、 RegistServlet（注册账户）

package com.look.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.security.GeneralSecurityException;
import javax.mail.MessagingException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.look.bean.User;
import com.look.dao.UserDao;
import com.look.util.SendMailUtils;
import com.look.util.UUIDUtils;
public class RegistServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    public void init() throws ServletException {
        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
        User user = new User();
        user.setUsername(username);
        user.setPassword(password);
        user.setNickname(nickname);
        user.setEmail(email);
        user.setCode(UUIDUtils.getUUID());
        System.out.println(user.getEmail() + "\t" + user.getCode());
        // 注册
        UserDao dao = new UserDao();
        dao.getConn();
        dao.regist(user);
        dao.closeConn();
        // 发送邮件
        try {
            SendMailUtils.sendMail(email, user.getCode());
            request.setCharacterEncoding("utf-8");
            response.setContentType("text/html;charset=utf-8");
            response.setCharacterEncoding("utf-8");
            PrintWriter out = response.getWriter();
            out.print("<html><head><meta charset='utf-8'/></head><body><p>邮件已经发送到"
                    + user.getEmail() + "中，请登录邮箱点击链接完成验证</p></body></html>");
            out.flush();
            out.close();
        } catch (GeneralSecurityException | MessagingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public void destroy() {
        super.destroy();
    }
}

7、 ActiveServlet（激活账户）

package com.look.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.look.dao.UserDao;
public class ActiveServlet extends HttpServlet
{
    private static final long serialVersionUID = 1L;
    public void init() throws ServletException {
        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.getConn();
        dao.activeByCode(code);
        dao.closeConn();
        // 重定向success.jsp
        try {
            request.getRequestDispatcher("success.jsp").forward(request,
                    response);
        } catch (ServletException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public void destroy() {
        super.destroy();
    }
}

8、 index.jsp（输入界面）

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//Dli HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dli">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
    <form action="RegistServlet" method="post">
        <ul>
            <li><label for="username">账号</label><input type="text" name="username" /></li>
            <li><label for="password">密码</label><input type="text" name="password" /></li>
            <li><label for="nickname">昵称</label><input type="text" name="nickname" /></li>
            <li><label for="email">邮箱</label><input type="text" name="email" /></li>
            <li><input type="submit" value="注册" /></li>
            <li><input type="reset" name="重写" /></li>
        </ul>
    </form>
</body>
</html>

9、 success.jsp（成功界面）

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
 <head>
  <title>成功激活</title>
 </head>
 <body>
  <script>
   window.onload = function(){
    alert("已成功激活");
   };
  </script>
 </body>
</html>

10、web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>javamail</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <servlet-name>RegistServlet</servlet-name>
    <servlet-class>com.look.servlet.RegistServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>RegistServlet</servlet-name>
    <url-pattern>/RegistServlet</url-pattern>
  </servlet-mapping>
  <servlet>
    <servlet-name>ActiveServlet</servlet-name>
    <servlet-class>com.look.servlet.ActiveServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>ActiveServlet</servlet-name>
    <url-pattern>/ActiveServlet</url-pattern>
  </servlet-mapping>
</web-app>