java.io.IOException:用SpringBoot编写Multipart时出现异常

Question

我想发送一封带有附件的电子邮件：

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("[e-mail]"));
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());
}
}

但我有一个例外：

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

Answer 1

Spring文档中给出的示例与您的代码不匹配：它创建了一个MimeMessageHelper对象，并使用它来定义主体和附加文件。

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("[e-mail]"));
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("[e-mail]"));
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，它并没有设置文本。在您的情况下，如果body String为null，您可能会遇到同样的问题。

下面的答案帮我弄明白了。https://stackoverflow.com/a/33015901/9905202