java - MimeMessage 电子邮件不会发送附件

Question

所以我有一个电子邮件模板，可以完美地发送没有附件的表单。一直在尝试将附件(从临时存储在文件夹中的服务器中获取它们)添加到要通过电子邮件发送的表单中。

我正在使用 Mail.java 类、emailService.java 类和表单的 Controller 来实现此功能。

我收到一个模糊的错误“java 空指针异常”。知道为什么我的消息不会发送吗？我认为这与代码中添加的 fileSystemResource 有关。但是在我的控制台中，它显示了文件...

电子邮件服务代码:

@Service
public class EmailService {

    private JavaMailSender javaMailSender;

    @Autowired
    public EmailService(JavaMailSender javaMailSender){
        this.javaMailSender = javaMailSender;
    }

    @Autowired
    public StorageService storage;
    @Autowired
    private SpringTemplateEngine templateEngine;

    public void sendSimpleMessage(Mail mail, DirectBind directBind) throws MessagingException, IOException {
        MimeMessage message = javaMailSender.createMimeMessage();
        MimeMessageHelper helper = new MimeMessageHelper(message,
                MimeMessageHelper.MULTIPART_MODE_MIXED_RELATED,
                StandardCharsets.UTF_8.name());

        helper.addAttachment("Mail_Icon.png", new ClassPathResource("static/images/Mail_Icon.png"));

        Context context = new Context();
        context.setVariables(mail.getModel());
        context.setVariable("directBind",directBind);
        String html = templateEngine.process("emailMessage", context);

        helper.setTo(mail.getTo());
        helper.setText(html, true);
        helper.setSubject(mail.getSubject());
        helper.setFrom(mail.getFrom());

//        List<Object> files = new ArrayList<>();
//        files.add(storage.getUploadDir());

        FileSystemResource allFiles= new FileSystemResource(new File(storage.getUploadDir()));
        helper.addAttachment(allFiles.getFilename(),allFiles);

        javaMailSender.send(message);
    }
}

Controller 中的发送函数:

@RequestMapping(value="/directBind",  params="send")
    public String send(Model model, @ModelAttribute(value="directBind") DirectBind directBind){
        List<String> businessAgencyList = directBind.getBusinessAgencyList();
        Mail mail = new Mail();
        mail.setFrom("no-reply@hgitservices.com");
        mail.setTo(new String[]{"stacief@hgitservices.com"});
        mail.setSubject("Oli Affiliate - AMS360 & PMA Data Checklist");

        Map<String, Object> mailModel = new HashMap<String, Object>();
        mail.setModel(mailModel);

       // List<Object> files = new ArrayList<>();
       // files.add(storageService.getUploadDir());
       // mail.setAttachments(files);

        try {
            emailService.sendSimpleMessage(mail, directBind);
        } catch (Exception e) {
            e.printStackTrace();
            return ("redirect:/?sentMessageFail");
        }
        return ("redirect:/?sentMessage");
    }

    @RequestMapping(value="/email")
    public String email(){
        return "emailMessage";
    }
}

我的邮件模型:

public class Mail {

    private String from;
    private String[] to;
    private String subject;
    private List<Object> attachments;
    private Map<String, Object> model;

    public Mail() {

    }

    public String getFrom() {
        return from;
    }

    public void setFrom(String from) {
        this.from = from;
    }

    public String[] getTo() {
        return to;
    }

    public void setTo(String[] to) {
        this.to = to;
    }

    public String getSubject() {
        return subject;
    }

    public void setSubject(String subject) {
        this.subject = subject;
    }

    public List<Object> getAttachments() {
        return attachments;
    }

    public void setAttachments(List<Object> attachments) {
        this.attachments = attachments;
    }


    public Map<String, Object> getModel() {
        return model;
    }

    public void setModel(Map<String, Object> model) {
        this.model = model;
    }

}

错误信息...

org.springframework.mail.MailSendException: Failed messages: java.lang.NullPointerException; message exception details (1) are:
Failed message 1:
java.lang.NullPointerException
	at javax.mail.internet.MimeUtility.getEncoding(MimeUtility.java:226)
	at javax.mail.internet.MimeUtility.getEncoding(MimeUtility.java:299)
	at javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1375)...

Answer 1

如果可以的话，我会把它添加为评论(代表低于 50)。

你可以尝试替换

helper.addAttachment(allFiles.getFilename(),allFiles);

与

helper.addAttachment(allFiles.getFilename(),allFiles.getFile());

编辑:

FileSystemResource allFiles= new FileSystemResource(new File(storage.getUploadDir() + "/filename.txt"));

遍历文件(可能需要调整):

File myDir = new File(storage.getUploadDir());
File[] myFiles = myDir.listFiles();

if (myFiles != null) {
    for (File cFile : myFiles) {
        helper.addAttachment(cFile.getName(), cFile);
    }
}