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2020
10-08

Java实现邮件发送的过程及代码详解

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>

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