<!-- 郵箱驗證碼 https://mvnrepository.com/artifact/org.apache.commons/commons-email -->
     <dependency>
           <groupId>org.apache.commons</groupId>
           <artifactId>commons-email</artifactId>
      <version>1.4</version>
</dependency>

 /**
     * 生成隨機驗證碼
     * @param number 幾位數
     * @return
     */
    @Override
    public String generateVerifyCode(int number) {
        Random random = new Random();
        StringBuilder builder = new StringBuilder();
        for (int i = 1; i <= number; i++) {
            builder.append(random.nextInt(10));
        }
        return builder.toString();
    }

 /**
     * 發送驗證碼
     * @param email
     * @return
     */
    @Override
    public int sendAuthCodeEmail(String email) {
        try {
            HtmlEmail mail = new HtmlEmail();
            /*發送郵件的服務器 126郵箱為smtp.126.com,163郵箱為163.smtp.com，QQ為smtp.qq.com*/
            mail.setHostName("smtp.qq.com");
            /*不設置發送的消息有可能是亂碼*/
            mail.setCharset("UTF-8");
            /*IMAP/SMTP服務的密碼*/
            mail.setAuthentication("發送消息的郵箱如：[email protected]", "密碼");
            /*發送郵件的郵箱和發件人*/
            mail.setFrom("發件郵箱", "發件人");
            /*使用安全鏈接*/
            mail.setSSLOnConnect(true);
            /*接收的郵箱*/
            mail.addTo("[email protected]");
            /*驗證碼*/
            String code = this.generateVerifyCode(6);
            /*設置郵件的主題*/
            mail.setSubject("注冊驗證碼");
            /*設置郵件的內容*/
            mail.setMsg("尊敬的用戶:你好! 注冊驗證碼為:" + code + "(有效期為一分鐘)");
            mail.send();//發送
        } catch (Exception e) {
            return 0;
        }
        return 1;
    }