从 JAVA 邮件发送到 IMAP 邮箱时附件文件名发生更改

Question

我正在通过JAVA邮件发送带有excel附件文件的邮件。每当我将电子邮件发送到IMAP邮箱时，它的文件名都会更改为无标题附件，而不是我为其他电子邮件地址传递的名称，它可以工作文件。

我已经联系了我提供的电子邮件，他们怀疑这是RFC 2231中默认格式的JAVa邮件格式问题，对于IMAP，它必须是RFC 2047/2231。

注意：应用程序使用 JAVA 8 部署在 Widfly 9 上。

这就是我调用该方法的方式：

ByteArrayOutputStream baos = new ByteArrayOutputStream(excel_bytes.length);
baos.write(excel_bytes, 0, excel_bytes.length);
DataSource aAttachment = new  ByteArrayDataSource(baos.toByteArray(),"application/vnd.ms-excel");
String to_email = tenant.getEmail(); 
email.sendRechargeBillEmail(to_email, aAttachment, file_name + ".xlsx",tenant.getCompanyName(), String.valueOf(job.getStartDate()), String.valueOf(job.getEndDate()));

这是具有电子邮件方法的类： 包 com.nextcontrols.rechargecomputing;

import java.awt.Color;
import java.io.ByteArrayOutputStream;
import java.io.UnsupportedEncodingException;
import java.util.Properties;
import java.util.logging.Logger;
import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.mail.BodyPart;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import javax.mail.internet.MimeUtility;
public class SendAttachmentInEmail {
private static final Logger logger = 
Logger.getLogger(SendAttachmentInEmail.class.getCanonicalName());
public void sendEmail(String to_email, DataSource attachment, String 
file_name, String from_email, String user_name, String password, String 
email_body, String email_subject) {
Properties props = new Properties();
props.put("mail.smtp.host", "mail2.nextcontrols.local");
Session session = Session.getDefaultInstance(props);
try { 
Message message = new MimeMessage(session);
message.setFrom(new InternetAddress(from_email));
message.setRecipients(Message.RecipientType.TO,
InternetAddress.parse(to_email));
message.setSubject(email_subject);
MimeBodyPart messageBodyPart = new MimeBodyPart();
messageBodyPart.setContent(email_body, "text/html; charset=utf-8");
Multipart multipart = new MimeMultipart();
multipart.addBodyPart(messageBodyPart);
MimeBodyPart mailattachment = new MimeBodyPart();
DataSource source = attachment;
mailattachment.setFileName(file_name);
mailattachment.setDataHandler(new DataHandler(source));
mailattachment.setDisposition(MimeBodyPart.ATTACHMENT); 
multipart.addBodyPart(mailattachment);
message.setContent(multipart);
Transport.send(message);
logger.info("////// Sent message successfully to "+ to_email);
} catch (MessagingException e) {
throw new RuntimeException(e);
}
}
public void sendRechargeBillEmail(String to_email, DataSource attachment, String file_name,String tenant_name, String start_date, String end_date){
String subject = "Billing - " + tenant_name + " - " + start_date + " to " + end_date;
String bodyText = "Please find attached your utility recharge bill for " + start_date + " to " + end_date;
String note = "<i>This is an automated email, please do not reply to this address</i>";
String fromText = "Regards,<br />-- <br />";
String disclaimerTop = "Privacy and Confidentiality Notice";
String disclaimerDown = " txt";
bodyText = bodyText + "<br /> <br /> <br />" + note + "<br />" + fromText + "<br />" + addColor (disclaimerTop, Color.GRAY ,"2") + "<br />" + addColor(disclaimerDown, Color.GRAY, "1");
sendEmail(to_email, attachment, file_name, "[e-mail]", "Billing", "billing", bodyText, subject);
}
public static String addColor(String msg, Color color, String size) {
String hexColor = String.format("#%06X",  (0xFFFFFF & color.getRGB()));
String colorMsg = "<FONT size = " "+ size +"" COLOR="" + hexColor + "">" + msg + "</FONT>";
return colorMsg;
}
}

Answer 1

如果您的 IMAP 服务器因为不理解 RFC 2231 而更改文件名，那么它确实需要更新。 RFC 2231 已有 20 年的历史。

通过将 JavaMail System 属性mail.mime.encodeparameters设置为"false"，可以禁用使用 RFC 2231 对文件名进行编码。