1.需要的依赖

<dependency>

<groupId>org.apache.poi</groupId>

<artifactId>poi</artifactId>

<version>3.17</version>

</dependency>

2. Util

import org.apache.poi.util.IOUtils;import org.springframework.beans.factory.annotation.Value;import org.springframework.core.io.ByteArrayResource;import org.springframework.mail.javamail.JavaMailSenderImpl;import org.springframework.mail.javamail.MimeMessageHelper;import org.springframework.stereotype.Service;import javax.mail.Session;import javax.mail.internet.MimeMessage;import java.io.InputStream;import java.util.List;import java.util.Map;import java.util.Properties;@Servicepublic class EmailUtil {    @Value("${email.host}")    private String host;    @Value("${email.from}")    private String from;    @Value("${email.password}")    private String password;    /**     * 发送邮件工具类     *     * @param tos     * @param subject     * @param emailContent     * @param isHtml     * @throws Exception     */    public void send(List
     
       tos, String subject, String emailContent, boolean isHtml,                     Map
      
        attachments) throws Exception {        generalSend(host, password, from, tos, subject, emailContent, isHtml, attachments);    }    private void generalSend(String host, String password, String from, List
       
         tos, String subject,                            String emailContent, boolean isHtml,                            Map
        
          attachments) throws Exception {        JavaMailSenderImpl senderImpl = new JavaMailSenderImpl();        //设定mail server        senderImpl.setHost(host);        //建立邮件消息,发送简单邮件和html邮件的区别        MimeMessage mailMessage = senderImpl.createMimeMessage();        MimeMessageHelper messageHelper = new MimeMessageHelper(mailMessage, 1, "UTF-8");        //设置收件人，寄件人        messageHelper.setTo(tos.toArray(new String[]{}));        messageHelper.setFrom(from);        messageHelper.setSubject(subject);        //true 表示启动HTML格式的邮件        messageHelper.setText(emailContent, isHtml);        //添加文件文件        if (attachments != null && attachments.size() > 0) {            for (String fileName : attachments.keySet()) {                InputStream in = attachments.get(fileName);                ByteArrayResource bar = new ByteArrayResource(IOUtils.toByteArray(in));                messageHelper.addAttachment(fileName, bar);            }        }        //设置邮箱属性        Properties prop = new Properties();        // 将这个参数设为true，让服务器进行认证,认证用户名和密码是否正确        prop.put("mail.smtp.auth", "true");        prop.put("mail.smtp.starttls.enable", "true");        prop.put("mail.smtp.host", host);        prop.put("mail.smtp.user", from);        prop.put("mail.smtp.pass", password);        //配置发送类信息        senderImpl.setJavaMailProperties(prop);        senderImpl.setUsername(from);        senderImpl.setPassword(password);        senderImpl.setSession(Session.getDefaultInstance(senderImpl.getJavaMailProperties()));        //发送邮件        senderImpl.send(mailMessage);    }}