【JavaWeb】之邮件收发

落日映苍穹つ 2024-04-01 10:02 118阅读 0赞

#### 【JavaWeb】邮件收发 ####

*  前言
 *  一、邮件的发送与接收原理
 *  二、发送简单文本邮件
 *  三、发送文本嵌入图片的邮件
 *  四、发送复杂邮件（文本嵌入图片，添加附件）
 *  五、发送注册提示邮件
 *  后记

--------------------

## 前言 ##

本文为JavaWeb基础邮件收发相关知识介绍~，**Java全栈学习路线可参考：** [【Java全栈学习路线】最全的Java学习路线及知识清单，Java自学方向指引][Java_Java_Java]，内含最全Java全栈学习技术清单~

## 一、邮件的发送与接收原理 ##

要在Internet上提供电子邮件功能，必须有专门的电子邮件服务器。电子邮箱(E-Mail地址)的获得需要在邮件服务器上进行申请。以QQ邮箱为例，需要从账户设置中开启POP3/SMTP服务。

用户连接上邮件服务器之后，要想给它发送一封电子邮件，需要遵循一定的通讯规则，SMTP协议就是用来定义这种通讯规则的。

用户若想从邮件服务器管理的电子邮箱当中接收一封电子邮件话，它连上邮件服务器后，也要遵循一定的通讯格式，POP3协议就是用来定义这种通讯格式的。

**邮件的发送与接收过程：**

*  场景假设xxx.@qq.com想给xxx.@sina.com发送邮件
 *  首先，xxx.@qq.com通过smtp协议连接到qq邮箱的smtp服务器，并将邮件发送给smtp服务器，紧接着，QQ邮箱的smtp服务器将邮件转投给sina的smtp服务器
 *  sina的smtp服务器将接收到的邮件存储到xxx.@sina.com的存储空间中，xxx.@sina.com通过POP3协议连接到sina的POP3服务器上收取邮件，POP3服务器从xxx.@sina.com账号的存储空间中取出邮件并将该邮件回送给xxx.@sina.com账户

## 二、发送简单文本邮件 ##

使用Java发送 E-mail 需要通过JavaMail API和Java Activation Framework得到两个jar包：mail.jar，activation.jar。

**代码实现：**

public class SendMail {
        
        public static void main(String[] args) throws MessagingException, GeneralSecurityException {
        
            //1 准备步骤
            //1.1 创建一个配置文件保存并读取信息
            Properties properties = new Properties();
            //1.2 设置邮件服务器（这里使用了QQ邮箱）
            properties.setProperty("mail.host","smtp.qq.com");
            //1.3 设置发送使用的协议
            properties.setProperty("mail.transport.protocol","smtp");
            //1.4 设置用户是否需要验证
            properties.setProperty("mail.smtp.auth","true");
            //1.5 关于QQ邮箱，还要设置SSL加密，加上以下代码即可
            MailSSLSocketFactory sf = new MailSSLSocketFactory();
            sf.setTrustAllHosts(true);
            properties.put("mail.smtp.ssl.enable", "true");
            properties.put("mail.smtp.ssl.socketFactory", sf);
            //2 连接服务器
            //2.1 创建session会话对象
            Session session = Session.getDefaultInstance(properties, new Authenticator() {
        
                @Override
                protected PasswordAuthentication getPasswordAuthentication() {
        
                    return new PasswordAuthentication("553401298@qq.com", "jyyylkflmkyybcif");
                }
            });
            //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);
            //2.2 通过session对象获取Transport对象（需要抛出异常）
            Transport transport = session.getTransport();
            //2.3 连接服务器(需要抛出异常)
            transport.connect("smtp.qq.com","553401298@qq.com","jyyylkflmkyybcif");
            //3 发送邮件
            //3.1 创建用来发送邮件的对象(需要传入session)
            MimeMessage mimeMessage = new MimeMessage(session);
            //3.2 创建邮件发送人
            mimeMessage.setFrom(new InternetAddress("553401298@qq.com"));
            //3.3 创建邮件接收人(可以同时发送给很多人（添加抄送）)
            mimeMessage.setRecipients(Message.RecipientType.TO, new InternetAddress[]{
        new InternetAddress("553401298@qq.com")});
            //3.4 创建邮件主题
            mimeMessage.setSubject("LUCK");
            //3.5 创建邮件正文
            mimeMessage.setContent("GOOD LUCK","text/html;charset=utf-8");
            //3.6 发送邮件
            transport.sendMessage(mimeMessage,mimeMessage.getAllRecipients());
            //===================================================================
            //4 关闭连接
            transport.close();
        }
    }

**运行结果：**  
![在这里插入图片描述][d5d0baf33a694e8fb4973746f992302f.jpeg_pic_center_pic_center]

## 三、发送文本嵌入图片的邮件 ##

**代码实现：**

public class SendImageEmail {
        
        public static void main(String[] args) throws GeneralSecurityException, MessagingException {
        
            //1.准备
            Properties properties = new Properties();
            properties.setProperty("mail.host","smtp.qq.com");
            properties.setProperty("mail.transport.protocol","smtp");
            properties.setProperty("mail.smtp.auth","true");
            MailSSLSocketFactory sf = new MailSSLSocketFactory();
            sf.setTrustAllHosts(true);
            properties.put("mail.smtp.ssl.enable", "true");
            properties.put("mail.smtp.ssl.socketFactory", sf);
            //2.连接服务器
            Session session = Session.getDefaultInstance(properties, new Authenticator() {
        
                @Override
                protected PasswordAuthentication getPasswordAuthentication() {
        
                    return new PasswordAuthentication("553401298@11.com", "jyyylkflmkyybcif");
                }
            });
            session.setDebug(true);
            Transport transport = session.getTransport();
            //连接服务器
            transport.connect("smtp.qq.com","553401298@qq.com","jyyylkflmkyybcif");
            //通过方法获取一个MimeMessage
            MimeMessage mimeMessage = setImgEmail(session);
            //设置发件人和收件人
            mimeMessage.setFrom(new InternetAddress("553401298@qq.com"));
            mimeMessage.setRecipients(Message.RecipientType.TO,new InternetAddress[]{
        new InternetAddress("553401298@qq.com")});
            //发送邮件
            transport.sendMessage(mimeMessage,mimeMessage.getAllRecipients());
            //关闭连接
            transport.close();
        }
        public static MimeMessage setImgEmail(Session session) throws MessagingException {
        
            //编写邮件内容
            //1.准备图片
            MimeBodyPart bodyPart = new MimeBodyPart();
            //2.将图片变为数据流
            //获取图片数据
            FileDataSource fileDataSource = new FileDataSource("src/resources/timg.jpg");
            //需要一个处理数据流的处理器来处理
            DataHandler dataHandler = new DataHandler(fileDataSource);
            //把图片数据放到邮件的正文中
            bodyPart.setDataHandler(dataHandler);
            //给图片设置一个名字
            bodyPart.setContentID("timg.jpg");
            //设置文本内容
            MimeBodyPart bodyPart2 = new MimeBodyPart();
            //给第二个邮件内容插入图片 通过图片ID插入
            bodyPart2.setContent("I need more space"+"<img src='cid:timg.jpg'>","text/html;charset=utf-8");
            //拼接邮件，描述关系
            MimeMultipart multipart = new MimeMultipart();
            multipart.addBodyPart(bodyPart);
            multipart.addBodyPart(bodyPart2);
            //描述邮件类型：related表示邮件为内嵌类型 mixed表示邮件为附件类型
            multipart.setSubType("related");
            MimeMessage mimeMessage = new MimeMessage(session);
            mimeMessage.setContent(multipart);
            //保存设置
            mimeMessage.setSubject("内嵌式邮件");
            mimeMessage.saveChanges();
            return mimeMessage;
        }
    }

**运行结果：**  
![在这里插入图片描述][ee7dc61efe9448a0be62e5c29f070eeb.jpeg_pic_center_pic_center]

## 四、发送复杂邮件（文本嵌入图片，添加附件） ##

**代码实现：**

**运行结果：**  
![在这里插入图片描述][4bd1a615692f46e6aff0c900285ee3d4.jpeg_pic_center_pic_center]

## 五、发送注册提示邮件 ##

**实体类：**

public class User {
        
        //实体类，用来封装用户信息
        private String username;
        private String password;
        private String email;
        public User(){
        
        }
        public User(String username, String password, String email) {
        
            this.username = username;
            this.password = password;
            this.email = email;
        }
        public String getUsername() {
        
            return username;
        }
        public void setUsername(String username) {
        
            this.username = username;
        }
        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;
        }
        @Override
        public String toString() {
        
            return "User{" +
                    "username='" + username + '\'' +
                    ", password='" + password + '\'' +
                    ", email='" + email + '\'' +
                    '}';
        }
    }

**发送邮件工具类：**

public class SendEmail extends Thread{
        
        //工具类，用来发送邮件
        //发件邮箱
        private String from = "553401298@qq.com";
        //邮箱的用户名
        private String username= "553401298@qq.com";
        //邮箱的授权码
        private String password = "jyyylkflmkyybcif";
        //邮箱服务器地址
        private String host = "smtp.qq.com";
        private User user;
        public SendEmail(User user){
        
            this.user=user;
        }
        @Override
        public void run() {
        
            try {
        
                Properties properties = new Properties();
                properties.setProperty("mail.host",host);
                properties.setProperty("mail.transport.protocol","smtp");
                properties.setProperty("mail.smtp.auth","true");
                MailSSLSocketFactory sf  = new MailSSLSocketFactory();
                sf.setTrustAllHosts(true);
                properties.put("mail.smtp.ssl.enable", "true");
                properties.put("mail.smtp.ssl.socketFactory", sf);
                Session session = Session.getDefaultInstance(properties, new Authenticator() {
        
                    @Override
                    protected PasswordAuthentication getPasswordAuthentication() {
        
                        return new PasswordAuthentication(username, password);
                    }
                });
                Transport transport = session.getTransport();
                transport.connect(host,username,password);
                //通过MimeMessage设置邮件详情
                MimeMessage mimeMessage = new MimeMessage(session);
                mimeMessage.setFrom(new InternetAddress(from));
                mimeMessage.setRecipients(Message.RecipientType.TO, new InternetAddress[]{
        
        new InternetAddress(user.getEmail())});
                mimeMessage.setSubject("注册成功回执");
                mimeMessage.setContent("您已成功注册，您的用户名为："+user.getUsername()
                                +",密码为："+user.getPassword()
                                +",请您妥善保管。"
                        ,"text/html;charset=utf-8");
                //通过transport对象传输邮件
                transport.sendMessage(mimeMessage,mimeMessage.getAllRecipients());
                transport.close();
            } catch (GeneralSecurityException e) {
        
                e.printStackTrace();
            } catch (NoSuchProviderException e) {
        
                e.printStackTrace();
            } catch (MessagingException e) {
        
                e.printStackTrace();
            }
        }
    }

**servlet类：**

public class RegisterServlet extends javax.servlet.http.HttpServlet{
        
        //servlet类用来获取前端数据，处理转发请求
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
            doPost(req,resp);
        }
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
            //接收用户请求，封装为对象
            String username = req.getParameter("username");
            String password = req.getParameter("password");
            String email = req.getParameter("email");
            User user = new User(username, password, email);
            //用户注册成功之后，给用户回执邮件
            //使用线程发送邮件，可以防止出现耗时，和网站注册人数过多的情况
            SendEmail sendEmail = new SendEmail(user);
            sendEmail.start();
            //提示用户查收注册回执邮件
            req.setAttribute("msg","注册成功，请查收回执邮件");
            req.getRequestDispatcher("info.jsp").forward(req,resp);
        }
    }

**web.xml：**

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
             version="4.0">
        <servlet>
            <servlet-name>RegisterServlet</servlet-name>
            <servlet-class>com.hooi.servlet.RegisterServlet</servlet-class>
        </servlet>
        <servlet-mapping>
            <servlet-name>RegisterServlet</servlet-name>
            <url-pattern>/rgs.do</url-pattern>
        </servlet-mapping>
    </web-app>

**运行结果：**  
![在这里插入图片描述][5de9848f3c5042c2b9cc864b4863bd3e.png_pic_center_pic_center]  
![在这里插入图片描述][87c3d6baf4214d8698bb6fa8dfae5cea.png_pic_center_pic_center]  
![在这里插入图片描述][a923e857513c4e6f9a6a7c9389ffb3ed.png_pic_center_pic_center]

## 后记 ##

**Java全栈学习路线可参考：**[【Java全栈学习路线】最全的Java学习路线及知识清单，Java自学方向指引][Java_Java_Java]，内含最全Java全栈学习技术清单~

[Java_Java_Java]: https://blog.csdn.net/qq_42146402/article/details/127133435
[d5d0baf33a694e8fb4973746f992302f.jpeg_pic_center_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/01/a7a012364c3d4f0592e719a84b52a2be.jpeg
[ee7dc61efe9448a0be62e5c29f070eeb.jpeg_pic_center_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/01/fa0676db9bcb46a58379934c58617a11.jpeg
[4bd1a615692f46e6aff0c900285ee3d4.jpeg_pic_center_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/01/58800481f71b48cdbf3b3d62ac37f2bd.jpeg
[5de9848f3c5042c2b9cc864b4863bd3e.png_pic_center_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/01/5b61f7b328004efb922e1f0c03ab3da0.png
[87c3d6baf4214d8698bb6fa8dfae5cea.png_pic_center_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/01/7a69951ebb634f30a59c0f5811a7ed81.png
[a923e857513c4e6f9a6a7c9389ffb3ed.png_pic_center_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/01/2de12e2d13e64a488183d455e3f9cf37.png