Java实现邮件发送

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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

在这里插入图片描述
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）
在这里插入图片描述
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)

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 + '\'' +
                '}';
    }
}

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();
        }


    }
}

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();
        }

    }

}

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>

msg.jsp

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

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>