前言：

1、郵件傳送協議 - SMTP，預設埠號 25。

用於把使用者郵件從一個伺服器轉到下一個伺服器

2、郵件接收協議 - POP3，預設埠號 110。

用於支援使用客戶端遠端管理在伺服器上的電子郵件

3、搭建郵件伺服器（易郵郵件伺服器 + Foxmail）：Email - 搭建自定義郵件伺服器

核心Jar包

核心程式碼

package com.jy.utils;

import java.util.Properties;
import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.Message.RecipientType;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import javax.mail.search.RecipientStringTerm;
import sun.nio.cs.MS1250;

/**
 * 郵箱工具
 */
public class MailUtil {
	
	public static void sendMail(String to,String code) throws Exception{

		// 1.建立連線物件
		Session session = Session.getDefaultInstance(new Properties(), new Authenticator() {
			@Override
			protected PasswordAuthentication getPasswordAuthentication() {
				return new PasswordAuthentication("
 
[email protected]", "123456");
			}
		});

		// 2.建立郵件物件
		Message message = new MimeMessage(session);
		message.setFrom(new InternetAddress("[email protected]"));
		message.setRecipient(RecipientType.TO, new InternetAddress(to));

		//主題
		message.setSubject("來自dt的啟用郵件");

		//正文
		message.setContent("<h1>來自dt的啟用郵件，點選連結啟用賬號：</h1><h3><a href='http://localhost:8081/javamail01/active?code="+code+"'>http://localhost:8081/javamail01/active?code="+code+"</a></h3>", "text/html;charset=utf-8");

		// 3.傳送啟用郵件
		Transport.send(message);
	}
}
 

package com.jy.web.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.jy.domain.User;
import com.jy.service.UserService;
import com.jy.service.impl.UserServiceImpl;
import com.jy.utils.UUIDUtil;

@WebServlet(urlPatterns="/regist")
public class RegistServlet extends HttpServlet{

	private static final long serialVersionUID = 1L;

	@Override
	protected void service(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
		try{
			req.setCharacterEncoding("utf-8");
			res.setCharacterEncoding("utf-8");

			String username = req.getParameter("username");
			String password = req.getParameter("password");
			String nickname = req.getParameter("nickname");
			String email = req.getParameter("email");

			User user = new User();
			user.setNickname(nickname);
			user.setUsername(username);
			user.setCode(UUIDUtil.code());
			user.setStatus(0);  // 狀態碼，0未啟用，1啟用
			user.setEmail(email);
			user.setPassword(password);

			UserService userService = new UserServiceImpl();
			userService.save(user);

			req.setAttribute("msg", "註冊成功，請郵箱啟用");
			req.getRequestDispatcher("/msg.jsp").forward(req, res);

		}catch(Exception e){
			
		}
	}
}
 

package com.jy.web.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.jy.domain.User;
import com.jy.service.UserService;
import com.jy.service.impl.UserServiceImpl;

/**
 * 啟用註冊郵箱
 */
@WebServlet(urlPatterns="/active")
public class ActiveServlet extends HttpServlet{
	
	private static final long serialVersionUID = 1L;

	@Override
	protected void service(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
		try{
			req.setCharacterEncoding("utf-8");
			res.setCharacterEncoding("utf-8");

			String code = req.getParameter("code");
			UserService userService = new UserServiceImpl();
			User user = userService.findByCode(code);
			if(user!=null){
				// 已經啟用
				user.setStatus(1);
				user.setCode(null);
				userService.update(user);
				req.setAttribute("msg", "啟用成功，請登入");
			}else{
				// 啟用失敗
				req.setAttribute("msg", "啟用失敗，重新啟用");
			}

			req.getRequestDispatcher("/msg.jsp").forward(req, res);

		}catch(Exception e){
			
		}
	}
}

<%@ 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>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
	<h1>使用者註冊的頁面</h1>
	<form action="regist" method="post">
		<table width="600" border="1">
			<tr>
				<td>使用者名稱：</td>
				<td><input type="text" name="username"/></td>
			</tr>
			<tr>
				<td>密碼：</td>
				<td><input type="password" name="password"/></td>
			</tr>
			<tr>
				<td>暱稱：</td>
				<td><input type="text" name="nickname"/></td>
			</tr>
			<tr>
				<td>郵箱：</td>
				<td><input type="text" name="email"/></td>
			</tr>
			<tr>
				<td colspan="2"><input type="submit" value="提交"></td>
			</tr>
		</table>
	</form>
	
</body>
</html>

<%@ 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>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>資訊反饋頁面</title>
</head>
<body>
	${msg}
</body>
</html>

原始碼下載：https://download.csdn.net/download/dream_weave/10869560