（三）JavaMail发送附件

代码如下：

package cases;

import com.sun.mail.util.MailSSLSocketFactory;

import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.mail.*;
import javax.mail.internet.*;
import java.util.Date;
import java.util.Properties;

/**
 * @description:
 * @author: lv
 * @time: 2020/5/25 17:53
 */
public class MailSendUtil {

    public static void main(String[] args) throws Exception{
        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

        // 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);
        prop.put("mail.smtp.ssl.enable", "true");
        prop.put("mail.smtp.ssl.socketFactory", sf);

        //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() {
            public PasswordAuthentication getPasswordAuthentication() {
                //发件人邮件用户名、授权码
                return new PasswordAuthentication("发件人@qq.com", "授权码");
            }
        });


        //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、通过session得到transport对象
        Transport ts = session.getTransport();

        //3、使用邮箱的用户名和授权码连上邮件服务器
        ts.connect("smtp.qq.com", "发件人@qq.com", "授权码");

        //4、创建邮件

        //创建邮件对象
        MimeMessage message = new MimeMessage(session);
        // 设置发送时间
        message.setSentDate(new Date());
        //设置多个收件人
        String users = "发件人1@qq.com,发件人2@qq.com";
        Address[] internetAddressTo = new InternetAddress().parse(users);

        //指明邮件的收件人，现在发件人和收件人是一样的，那就是自己给自己发
        message.setRecipients(Message.RecipientType.TO, internetAddressTo);
        //邮件的标题
        message.setSubject("测试报告");


        Multipart multipart = new MimeMultipart();
        //邮件正文
        BodyPart contentPart = new MimeBodyPart();
        contentPart.setContent("测试报告见附件", "text/html;charset=utf-8");
        multipart.addBodyPart(contentPart);
        
        BodyPart attachmentPart = new MimeBodyPart();
        DataSource source = new FileDataSource("./test-output/index.html");
        DataHandler attachment = new DataHandler(source);
        attachmentPart.setDataHandler(new DataHandler(source));
        //避免中文乱码的处理
        attachmentPart.setFileName(MimeUtility.encodeWord(attachment.getName()));
        multipart.addBodyPart(attachmentPart);

        //邮件的文本内容
        message.setContent(multipart);
        message.saveChanges();

        //5、发送邮件
        ts.sendMessage(message, message.getAllRecipients());

        ts.close();
    }
}

发送多个附件，需要参考上面的代码，大概的思路

Multipart multipart = new MimeMultipart();   
            //邮件正文  
            BodyPart contentPart = new MimeBodyPart();  
            contentPart.setContent(mail.getContent(), "text/html;charset=utf-8");  
            multipart.addBodyPart(contentPart);  
            //邮件附件  
            if(attachments != null) {  
                for(File attachment : attachments) {  
                    BodyPart attachmentPart = new MimeBodyPart();  
                    DataSource source = new FileDataSource(attachment);  
                    attachmentPart.setDataHandler(new DataHandler(source));  
                    //避免中文乱码的处理  
                    attachmentPart.setFileName(MimeUtility.encodeWord(attachment.getName()));  
                    multipart.addBodyPart(attachmentPart);  
                }  
            }  
            message.setContent(multipart);  
            //保存邮件  
            message.saveChanges();  
            Transport.send(message);