1、配置邮箱的POP3/SMTP服务和IMAP/SMTP服务

这里使用的是QQ邮箱,进入设置-账户，开启下服务。

开启后获取授权码，保存自己客户端授权码。

2、导入依赖和一些默认#配置新的

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-mail</artifactId>
        </dependency>

注意，password不是邮箱的密码，而是授权码。

spring.mail.host=smtp.qq.com
spring.mail.port=587
spring.mail.username=xxxxx@qq.com
spring.mail.password=xxxxxxxxxxx

以上配置好了，我们可以写一些demo。

3、发送邮件

• 简单消息

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

    @Autowired
    private JavaMailSender mailSender;
    @Test
    public void sendMail(){
        SimpleMailMessage message = new SimpleMailMessage();
        message.setFrom("xxxxxxxx@qq.com");
        message.setTo("xxxxxxxx@qq.com");
        message.setSubject("主题");
        message.setText("文本内容");
        mailSender.send(message);
    }
}

• 复杂消息

对于复杂消息，我们可以编辑html消息模板，以及实现动态解析的功能。另外还能够携带多附件。

public void sendComplexMsg() throws MessagingException {

        MimeMessage mimeMessage = mailSender.createMimeMessage();
        //多文件上传
        MimeMessageHelper helper = new MimeMessageHelper(mimeMessage, true);
        helper.setFrom("xxxxxxxx@qq.com");
        helper.setTo("xxxxxxxx@qq.com");
        helper.setSubject("面试通知");
        //发送html格式
        helper.setText(parse(getMod(),getParams()),true);

        helper.addAttachment("xxxx公司简章.txt", new File("附件.txt"));
        helper.addAttachment("xxxx公司入职须知.txt", new File("附件.txt"));
        mailSender.send(mimeMessage);

    }

动态解析模板

 private String getMod() {
        return "<div>\n" +
                "&nbsp;&nbsp;尊敬的#{username}先生（女士），欢迎您应聘我公司#{postion}职位，您的学识、经历给我们留下了良好的印象。为了彼此进一步的了解，特邀请你在#{joinTime}参加面试。收到请回复，谢谢！\n" +
                "电话：#{compTel},公司地址：#{compAddr}，收到请回复，谢谢！\n" +
                "</div>\n" +
                "<br>\n" +
                "<div style=\"float:right\">\n" +
                "\t<div>#{dept}</div>\n" +
                "\t<div>#{sendTime}</div>\n" +
                "</div>";
    }

    private String parse(String mod, Map<String, String> params) {
        int length = mod.length();
        int left = 0;
        while ((left = mod.indexOf("#")) != -1 && left < length) {
            for (int right = left; right < length; right++) {
                if (mod.charAt(right) == '}') {
                    String key = mod.substring(left + 2, right);
                    mod = mod.substring(0, left) + params.get(key) + mod.substring(right + 1);
                    length = mod.length();
                    left += key.length() + 1;
                    break;
                }
            }
        }
        return mod;
    }
	
	 public Map<String, String> getParams() {
        HashMap<String, String> map = new HashMap<>();
        map.put("username", "xxxx");
        map.put("postion", "Java开发");
        map.put("joinTime", "2023年5月26日下午3:00");
        map.put("compTel", "xxxxxxx");
        map.put("compAddr", "xxxxxx");
        map.put("dept", "xxxxxxxx");
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日");
        map.put("sendTime", sdf.format(new Date()));
        return map;
    }

4、整合工具类

对于以上的内容，我们需要来把它整合成一个工具来使用。

/**
 * mail工具类
 */
@Component
public class MailUtil {

    @Autowired
    private JavaMailSender mailSender;

    @Value("${spring.mail.username}")
    private String clientMail;


    /**
     * @param subject  主题
     * @param content  内容
     * @param fileList 文件
     * @param to       接收方
     * @throws MessagingException
     */
    private void sendMail(String subject, String content, List<File> fileList, String to,boolean isHtml) throws MessagingException {
        MimeMessage mimeMessage = mailSender.createMimeMessage();
        //是否为多文件上传
        boolean mutipart = !CollectionUtils.isEmpty(fileList);
        MimeMessageHelper helper = new MimeMessageHelper(mimeMessage, mutipart);
        helper.setFrom(clientMail);
        helper.setTo(to);
        helper.setSubject(subject);
        //发送html格式
        helper.setText(content, isHtml);

        //附件
        for (File file : fileList) {
            helper.addAttachment(file.getName(), file);
        }

        mailSender.send(mimeMessage);

    }

    /**
     * 发送Html邮件
     * @param subject
     * @param mod
     * @param params
     * @param to
     * @param fileList
     * @throws MessagingException
     */
    public void sendHtmlMsg(String subject, String mod, Map<String, String> params, String to, List<File> fileList) throws MessagingException {
        sendMail(subject, parse(mod, params), fileList, to,true);
    }

    /**
     * 发送简单消息邮件
     * @param subject
     * @param msg
     * @param to
     * @param fileList
     * @throws MessagingException
     */

    public void sendSimpleMsg(String subject, String msg, String to, List<File> fileList) throws MessagingException {
        sendMail(subject,msg,fileList,to,false);
    }

    private String parse(String mod, Map<String, String> params) {
        int length = mod.length();
        int left = 0;
        while ((left = mod.indexOf("#")) != -1 && left < length) {
            for (int right = left; right < length; right++) {
                if (mod.charAt(right) == '}') {
                    String key = mod.substring(left + 2, right);
                    mod = mod.substring(0, left) + params.get(key) + mod.substring(right + 1);
                    length = mod.length();
                    left += key.length() + 1;
                    break;
                }
            }
        }
        return mod;
    }

}

• 编写测试类来测试工具类

  @Test
    public void testMailUtil() throws MessagingException {
        String subject = "面试通知";
        String to = "xxxxxxx@qq.com";
        List<File> fileList = new ArrayList<>();
        fileList.add(new File("附件.txt"));
        fileList.add(new File("附件.txt"));
        mailUtil.sendHtmlMsg(subject,getMod(),getPart

效果图如下