java.io.IOException: 使用 Spring Boot 编写 Multipart 时出现异常

Question

我想发送一封带附件的电子邮件：

  public void sendMailWithAttachment(String to, String subject, String body, String fileToAttach) {

        MimeMessagePreparator preparator = mimeMessage -> {

            mimeMessage.setRecipient(Message.RecipientType.TO, new InternetAddress(to));
            mimeMessage.setFrom(new InternetAddress("admin@gmail.com"));
            mimeMessage.setSubject(subject);
            mimeMessage.setText(body);

            FileSystemResource file = new FileSystemResource(new File(fileToAttach));
            System.out.println(file.contentLength());
            MimeMessageHelper helper = new MimeMessageHelper(mimeMessage, true);
            helper.addAttachment("logo.jpg", file);
        };

        try {
            javaMailSender.send(preparator);
        }
        catch (MailException ex) {
            // simply log it and go on...
            System.err.println(ex.getMessage());
        }
    }

但我有这个例外：

Failed messages: javax.mail.MessagingException: IOException while sending message;
  nested exception is:
    java.io.IOException: Exception writing Multipart

Answer 1

Spring documentation 中给出的示例与您的代码不匹配：它创建了一个 MimeMessageHelper 对象并使用它来定义正文和附件。

你应该这样做：

public void sendMailWithAttachment(String to, String subject, String body, String fileToAttach) {

        MimeMessagePreparator preparator = mimeMessage -> {

            MimeMessageHelper message = new MimeMessageHelper(mimeMessage, true, "UTF-8");
            message.setRecipient(Message.RecipientType.TO, new InternetAddress(to));
            message.setFrom(new InternetAddress("admin@gmail.com"));
            message.setSubject(subject);
            message.setText(body);

            FileSystemResource file = new FileSystemResource(new File(fileToAttach));
            message.addAttachment("logo.jpg", file);
        };

        try {
            javaMailSender.send(preparator);
        }
        catch (MailException ex) {
            // simply log it and go on...
            System.err.println(ex.getMessage());
        }
    }

Answer 2

我会以不同的方式创建 MimeMessagePreparator 并使用 Streams 读取文件。

public void sendMailWithAttachment(String to, String subject, String body, String fileToAttach) {

        MimeMessagePreparator preparator = mimeMessage -> {

            FileInputStream inputStream = new FileInputStream(new File(fileToAttach));

            MimeMessageHelper message = new MimeMessageHelper(mimeMessage, true, "UTF-8");
            message.setRecipient(Message.RecipientType.TO, new InternetAddress(to));
            message.setFrom(new InternetAddress("admin@gmail.com"));
            message.setSubject(subject);
            message.setText(body);            
            message.addAttachment("logo.jpg", new ByteArrayResource(IOUtils.toByteArray(inputStream)));
  
        };

        try {
            javaMailSender.send(preparator);
        }
        catch (MailException ex) {
            // simply log it and go on...
            System.err.println(ex.getMessage());
        }
    }

Answer 3

这可能有多种原因。对我来说，这不是设置文本。在您的情况下，如果 body String 为 null，您可能会遇到同样的问题。

下面的回答帮助我弄明白了。

java.io.IOException: 使用 Spring Boot 编写 Multipart 时出现异常

java.io.IOException: Exception writing Multipart with SpringBoot

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