org.springframework.boot
 spring-boot-starter-mail

spring:
 mail:
 # 邮件服务地址
 host: smtp.163.com
 # 端口,可不写默认
 port: 25
 # 编码格式
 default-encoding: utf-8
 # 用户名
 username: xxx@163.com
 # 授权码，就是我们刚才准备工作获取的代码
 password: xxx
 # 其它参数
 properties:
  mail:
  smtp:
   # 如果是用 SSL 方式，需要配置如下属性,使用qq邮箱的话需要开启
   ssl:
   enable: true
   required: true
   # 邮件接收时间的限制，单位毫秒
   timeout: 10000
   # 连接时间的限制，单位毫秒
   connectiontimeout: 10000
   # 邮件发送时间的限制，单位毫秒
   writetimeout: 10000

@Service
public class MailService {
 private static final Logger logger = LoggerFactory.getLogger(MailServiceImpl.class);

 @Autowired
 private JavaMailSender mailSender;

 private static final String SENDER = "xxx@163.com";

 /**
  * 发送普通邮件
  *
  * @param to  收件人
  * @param subject 主题
  * @param content 内容
  */
 @Override
 public void sendSimpleMailMessge(String to, String subject, String content) {
  SimpleMailMessage message = new SimpleMailMessage();
  message.setFrom(SENDER);
  message.setTo(to);
  message.setSubject(subject);
  message.setText(content);
  try {
   mailSender.send(message);
  } catch (Exception e) {
   logger.error("发送简单邮件时发生异常!", e);
  }
 }

 /**
  * 发送 HTML 邮件
  *
  * @param to  收件人
  * @param subject 主题
  * @param content 内容
  */
 @Override
 public void sendMimeMessge(String to, String subject, String content) {
  MimeMessage message = mailSender.createMimeMessage();
  try {
   //true表示需要创建一个multipart message
   MimeMessageHelper helper = new MimeMessageHelper(message, true);
   helper.setFrom(SENDER);
   helper.setTo(to);
   helper.setSubject(subject);
   helper.setText(content, true);
   mailSender.send(message);
  } catch (MessagingException e) {
   logger.error("发送MimeMessge时发生异常！", e);
  }
 }

 /**
  * 发送带附件的邮件
  *
  * @param to  收件人
  * @param subject 主题
  * @param content 内容
  * @param filePath 附件路径
  */
 @Override
 public void sendMimeMessge(String to, String subject, String content, String filePath) {
  MimeMessage message = mailSender.createMimeMessage();
  try {
   //true表示需要创建一个multipart message
   MimeMessageHelper helper = new MimeMessageHelper(message, true);
   helper.setFrom(SENDER);
   helper.setTo(to);
   helper.setSubject(subject);
   helper.setText(content, true);

   FileSystemResource file = new FileSystemResource(new File(filePath));
   String fileName = file.getFilename();
   helper.addAttachment(fileName, file);

   mailSender.send(message);
  } catch (MessagingException e) {
   logger.error("发送带附件的MimeMessge时发生异常！", e);
  }
 }

 /**
  * 发送带静态文件的邮件
  *
  * @param to  收件人
  * @param subject 主题
  * @param content 内容
  * @param rscIdMap 需要替换的静态文件
  */
 @Override
 public void sendMimeMessge(String to, String subject, String content, Map rscIdMap) {
  MimeMessage message = mailSender.createMimeMessage();
  try {
   //true表示需要创建一个multipart message
   MimeMessageHelper helper = new MimeMessageHelper(message, true);
   helper.setFrom(SENDER);
   helper.setTo(to);
   helper.setSubject(subject);
   helper.setText(content, true);

   for (Map.Entry entry : rscIdMap.entrySet()) {
    FileSystemResource file = new FileSystemResource(new File(entry.getValue()));
    helper.addInline(entry.getKey(), file);
   }
   mailSender.send(message);
  } catch (MessagingException e) {
   logger.error("发送带静态文件的MimeMessge时发生异常！", e);
  }
 }
}

@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringbooEmailDemoApplicationTests {

 @Autowired
 private MailService mailService;

 private static final String TO = "xxx@qq.com";
 private static final String SUBJECT = "测试邮件";
 private static final String COnTENT= "test content";

 /**
  * 测试发送普通邮件
  */
 @Test
 public void sendSimpleMailMessage() {
  mailService.sendSimpleMailMessge(TO, SUBJECT, CONTENT);
 }

 /**
  * 测试发送html邮件
  */
 @Test
 public void sendHtmlMessage() {
  String htmlStr = "
Test
";
  mailService.sendMimeMessge(TO, SUBJECT, htmlStr);
 }

 /**
  * 测试发送带附件的邮件
  * @throws FileNotFoundException
  */
 @Test
 public void sendAttachmentMessage() throws FileNotFoundException {
  File file = ResourceUtils.getFile("classpath:test.txt");
  String filePath = file.getAbsolutePath();
  mailService.sendMimeMessge(TO, SUBJECT, CONTENT, filePath);
 }

 /**
  * 测试发送带附件的邮件
  * @throws FileNotFoundException
  */
 @Test
 public void sendPicMessage() throws FileNotFoundException {
  String htmlStr = "测试：图片1 
  
图片2 
 ";
  Map rscIdMap = new HashMap<>(2);
  rscIdMap.put("pic1", ResourceUtils.getFile("classpath:pic01.jpg").getAbsolutePath());
  rscIdMap.put("pic2", ResourceUtils.getFile("classpath:pic02.jpg").getAbsolutePath());
  mailService.sendMimeMessge(TO, SUBJECT, htmlStr, rscIdMap);
 }
}