请求处理失败：javax.mail.AuthenticationFailedException]的根本原因是javax.mail.AuthenticationFailedException：空

Question

当尝试使用spring和angular发送邮件时出现此错误：

  

错误11175-[io-8090-exec-10] oaccC [。[。[/]。[dispatcherServlet]：路径为[]的上下文中servlet [dispatcherServlet]的Servlet.service（）引发了异常[Request处理失败；嵌套的异常是java.lang.RuntimeException：javax.mail.AuthenticationFailedException]，其根本原因是   javax.mail.AuthenticationFailedException：空

我已经在pom.xml文件中导入了javax.mail：

<dependency>
    <groupId> javax.mail </groupId>
    <artifactId> mail </artifactId>
    <version> 1.4 </version>
</dependency> 

这是我的代码：

public static boolean sendMail(MailMessageRequest messageRequest) {

    final String username = "----";
    final String password = "----";

    Properties props = new Properties();
    props.put("mail.smtp.auth", "true");
    props.put("mail.smtp.starttls.enable", "true");
    props.put("mail.smtp.host", "smtp.gmail.com");
    props.put("mail.smtp.port", "587");

    Session session = Session.getInstance(props, new javax.mail.Authenticator() {
        protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication(username, password);
        }
    });

    try {
        MimeMessage message = new MimeMessage(session);
        message.setFrom(new InternetAddress(username, "TestingApp"));
        message.setSender(new InternetAddress(username, "TestingApp"));
        message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(messageRequest.getSentTo()));
        message.setSubject(messageRequest.getSubject());
        message.setContent(messageRequest.getBody(), "text/html");
        message.setReplyTo(messageRequest.getReplayTo());
        Transport.send(message);
        log.info("A mail has been sent to " + messageRequest.getSentTo() + " at --> " + new Date());
    } catch (MessagingException | UnsupportedEncodingException e) {
        throw new RuntimeException(e);
    }
    return true;
}

所以我不明白是什么问题。