Java实现邮件发送

一、邮件服务器与传输协议

• 要在网络上实现邮件功能，必须要有专门的邮件服务器。这些邮件服务器类似于现实生活中的邮局，它主要负责接收用户投递过来的邮件，并把邮件投递到邮件接收者的电子邮箱中。

• SMTP服务器地址：一般是 smtp.xxx.com，比如163邮箱是smtp.163.com，qq邮箱是smtp.qq.com。

• SMTP协议

  通常把处理用户smtp请求(邮件发送请求)的服务器称之为SMTP服务器(邮件发送服务器)。

• POP3协议

  通常把处理用户pop3请求(邮件接收请求)的服务器称之为POP3服务器(邮件接收服务器)。

二、Java发送邮件

使用到的jar包：

• mail.jar
• activation.jar

QQ邮箱需获取相应的权限：

QQ邮箱–>邮箱设置–>账户–>POP3/IMAP/SMTP/Exchange/CardDAV/CalDAV服务 开启POP3/SMTP服务，然后获取16位授权码（注意不要将授权码泄露，一个账户可以拥有多个授权码）

Java实现纯文本邮件发送

package org.westos.email;

import com.sun.mail.util.MailSSLSocketFactory;

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

public class SendEamil {
    public static void main(String[] args) throws MessagingException, GeneralSecurityException {
        //创建一个配置文件并保存
        Properties properties = new Properties();

        properties.setProperty("mail.host","smtp.qq.com");

        properties.setProperty("mail.transport.protocol","smtp");

        properties.setProperty("mail.smtp.auth","true");


        //QQ存在一个特性设置SSL加密
        MailSSLSocketFactory sf = new MailSSLSocketFactory();
        sf.setTrustAllHosts(true);
        properties.put("mail.smtp.ssl.enable", "true");
        properties.put("mail.smtp.ssl.socketFactory", sf);

        //创建一个session对象
        Session session = Session.getDefaultInstance(properties, new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication("619046217@qq.com","16位授权码");
            }
        });

        //开启debug模式
        session.setDebug(true);

        //获取连接对象
        Transport transport = session.getTransport();

        //连接服务器
        transport.connect("smtp.qq.com","619046217@qq.com","16位授权码");

        //创建邮件对象
        MimeMessage mimeMessage = new MimeMessage(session);

        //邮件发送人
        mimeMessage.setFrom(new InternetAddress("619046217@qq.com"));

        //邮件接收人
        mimeMessage.setRecipient(Message.RecipientType.TO,new InternetAddress("875203654@qq.com"));

        //邮件标题
        mimeMessage.setSubject("Hello Mail");

        //邮件内容
        mimeMessage.setContent("我的想法是把代码放进一个循环里","text/html;charset=UTF-8");

        //发送邮件
        transport.sendMessage(mimeMessage,mimeMessage.getAllRecipients());

        //关闭连接
        transport.close();
    }
}

Java实现文本图片附件复杂的邮件发送
MIME（多用途互联网邮件扩展类型）

MimeBodyPart类

javax.mail.internet.MimeBodyPart类 表示的是一个MIME消息，它和MimeMessage类一样都是从Part接口继承过来。

MimeMultipart类

javax.mail.internet.MimeMultipart是抽象类 Multipart的实现子类,它用来组合多个MIME消息。一个MimeMultipart对象可以包含多个代表MIME消息的MimeBodyPart对象

package org.westos.email;

import com.sun.mail.util.MailSSLSocketFactory;

import javax.activation.DataHandler;
import javax.activation.FileDataSource;
import javax.mail.*;
import javax.mail.internet.*;
import java.security.GeneralSecurityException;
import java.util.Properties;

public class SendComplexEmail {
    public static void main(String[] args) throws GeneralSecurityException, MessagingException {
        Properties prop = new Properties();
        prop.setProperty("mail.host", "smtp.qq.com");  设置QQ邮件服务器
        prop.setProperty("mail.transport.protocol", "smtp"); // 邮件发送协议
        prop.setProperty("mail.smtp.auth", "true"); // 需要验证用户名密码

        // QQ邮箱设置SSL加密
        MailSSLSocketFactory sf = new MailSSLSocketFactory();
        sf.setTrustAllHosts(true);
        prop.put("mail.smtp.ssl.enable", "true");
        prop.put("mail.smtp.ssl.socketFactory", sf);

        //1、创建定义整个应用程序所需的环境信息的 Session 对象
        Session session = Session.getDefaultInstance(prop, new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                //传入发件人的姓名和授权码
                return new PasswordAuthentication("619046217@qq.com","16位授权码");
            }
        });

        //2、通过session获取transport对象
        Transport transport = session.getTransport();

        //3、通过transport对象邮箱用户名和授权码连接邮箱服务器
        transport.connect("smtp.qq.com","619046217@qq.com","16位授权码");

        //4、创建邮件,传入session对象
        MimeMessage mimeMessage = complexEmail(session);

        //5、发送邮件
        transport.sendMessage(mimeMessage,mimeMessage.getAllRecipients());

        //6、关闭连接
        transport.close();


    }

    public static MimeMessage complexEmail(Session session) throws MessagingException {
        //消息的固定信息
        MimeMessage mimeMessage = new MimeMessage(session);

        //发件人
        mimeMessage.setFrom(new InternetAddress("619046217@qq.com"));
        //收件人
        mimeMessage.setRecipient(Message.RecipientType.TO,new InternetAddress("619046217@qq.com"));
        //邮件标题
        mimeMessage.setSubject("带图片和附件的邮件");

        //邮件内容
        //准备图片数据
        MimeBodyPart image = new MimeBodyPart();
        DataHandler handler = new DataHandler(new FileDataSource("E:\\IdeaProjects\\WebEmail\\resources\\测试图片.png"));
        image.setDataHandler(handler);
        image.setContentID("test.png"); //设置图片id

        //准备文本
        MimeBodyPart text = new MimeBodyPart();
        text.setContent("这是一段文本<img src='cid:test.png'>","text/html;charset=utf-8");

        //附件
        MimeBodyPart appendix = new MimeBodyPart();
        appendix.setDataHandler(new DataHandler(new FileDataSource("E:\\IdeaProjects\\WebEmail\\resources\\测试文件.txt")));
        appendix.setFileName("test.txt");

        //拼装邮件正文
        MimeMultipart mimeMultipart = new MimeMultipart();
        mimeMultipart.addBodyPart(image);
        mimeMultipart.addBodyPart(text);
        mimeMultipart.setSubType("related");//文本和图片内嵌成功

        //将拼装好的正文内容设置为主体
        MimeBodyPart contentText = new MimeBodyPart();
        contentText.setContent(mimeMultipart);

        //拼接附件
        MimeMultipart allFile = new MimeMultipart();
        allFile.addBodyPart(appendix);//附件
        allFile.addBodyPart(contentText);//正文
        allFile.setSubType("mixed"); //正文和附件都存在邮件中，所有类型设置为mixed


        //放到Message消息中
        mimeMessage.setContent(allFile);
        mimeMessage.saveChanges();//保存修改

        return mimeMessage;
    }
}

JavaWeb发送邮件(网站注册成功发送提示邮件)

1. User

   package org.westos.mail;
   
   public class User {
       private String name;
       private String password;
       private String mail;
   
       public User() {
       }
   
       public User(String name, String password, String mail) {
           this.name = name;
           this.password = password;
           this.mail = mail;
       }
   
       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 getMail() {
           return mail;
       }
   
       public void setMail(String mail) {
           this.mail = mail;
       }
   
       @Override
       public String toString() {
           return "User{" +
                   "name='" + name + '\'' +
                   ", password='" + password + '\'' +
                   ", mail='" + mail + '\'' +
                   '}';
       }
   }
   
   

2. Servlet

   package org.westos.mail;
   
   import javax.servlet.ServletException;
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   import java.io.IOException;
   
   public class Servlet extends javax.servlet.http.HttpServlet {
       protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           doGet(request,response);
       }
   
       protected void doGet(HttpServletRequest request, HttpServletResponse response) {
           //处理前端请求
           String username = request.getParameter("username");
           String password = request.getParameter("password");
           String email = request.getParameter("email");
   
           //将信息封装进user对象
           User user = new User(username, password, email);
   
           SendMail sendMail = new SendMail(user);
           sendMail.start(); //开启线程
   
           request.setAttribute("msg","发送成功");
           try {
               request.getRequestDispatcher("msg.jsp").forward(request,response);
           } catch (ServletException e) {
               e.printStackTrace();
           } catch (IOException e) {
               e.printStackTrace();
           }
   
   
       }
   }
   
   

3. SengMail

   package org.westos.mail;
   
   import com.sun.mail.util.MailSSLSocketFactory;
   
   import javax.mail.*;
   import javax.mail.internet.AddressException;
   import javax.mail.internet.InternetAddress;
   import javax.mail.internet.MimeMessage;
   import java.security.GeneralSecurityException;
   import java.security.PublicKey;
   import java.util.Properties;
   
   public class SendMail extends Thread {
       //发件人信息
       private String From = "619046217@qq.com";
       //发件人邮箱
       private String recipient = "619046217@qq.com";
       //邮箱密码
       private String password = "16位授权码";
       //邮件发送的服务器
       private String host = "smtp.qq.com";
   
       //收件人信息
       private User user;
       public SendMail(User user){
           this.user = user;
       }
   
       @Override
       public void run() {
           try {
               Properties properties = new Properties();
   
               properties.setProperty("mail.host","smtp.qq.com");
   
               properties.setProperty("mail.transport.protocol","smtp");
   
               properties.setProperty("mail.smtp.auth","true");
   
               //QQ存在一个特性设置SSL加密
               MailSSLSocketFactory sf = null;
               try {
                   sf = new MailSSLSocketFactory();
               } catch (GeneralSecurityException e) {
                   e.printStackTrace();
               }
               sf.setTrustAllHosts(true);
               properties.put("mail.smtp.ssl.enable", "true");
               properties.put("mail.smtp.ssl.socketFactory", sf);
   
               //创建一个session对象
               Session session = Session.getDefaultInstance(properties, new Authenticator() {
                   @Override
                   protected PasswordAuthentication getPasswordAuthentication() {
                       return new PasswordAuthentication(recipient,password);
                   }
               });
   
               //开启debug模式
               session.setDebug(true);
   
               //获取连接对象
               Transport transport = null;
               try {
                   transport = session.getTransport();
               } catch (NoSuchProviderException e) {
                   e.printStackTrace();
               }
   
               //连接服务器
               transport.connect(host,From,password);
   
   
               //创建一个邮件发送对象
               MimeMessage mimeMessage = new MimeMessage(session);
               //邮件发送人
               mimeMessage.setFrom(new InternetAddress(recipient));
   
               //邮件接收人
               mimeMessage.setRecipient(Message.RecipientType.TO,new InternetAddress(user.getMail()));
   
               //邮件标题
               mimeMessage.setSubject("网站注册成功");
   
               //邮件内容
               mimeMessage.setContent("网站注册成功，密码为"+user.getPassword()+"，请妥善保管密码","text/html;charset=UTF-8");
   
               //发送邮件
               transport.sendMessage(mimeMessage,mimeMessage.getAllRecipients());
   
               transport.close();
   
           }catch (Exception e){
               e.printStackTrace();
           }
   
       }
   
   }
   

4. register.jsp

   <%@ page contentType="text/html;charset=UTF-8" language="java" %>
   <html>
   <head>
       <title>注册页面</title>
   </head>
   <body>
   
   <form action="${pageContext.request.contextPath}/a.do" method="post">
       <p>用户名：<input type="text" name="username" required></p>
       <p>密码：<input type="password" name="password" required></p>
       <p>邮箱：<input type="email" name="email" required></p>
       <p><input type="submit" value="提交"></p>
   </form>
   </body>
   </html>
   

5. msg.jsp

   <%@ page contentType="text/html;charset=UTF-8" language="java" %>
   <html>
   <head>
       <title>Title</title>
   </head>
   <body>
   ${msg}
   </body>
   </html>
   

6. 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>Servlet</servlet-name>
           <servlet-class>org.westos.mail.Servlet</servlet-class>
       </servlet>
   
       <servlet-mapping>
           <servlet-name>Servlet</servlet-name>
           <url-pattern>/a.do</url-pattern>
       </servlet-mapping>
   </web-app>