即使字符串采用UTF-8，电子邮件主题仍以CP1252编码设置

Question

The file new1.txt contains UTF-8 string which is sent as subject. But the received email will show the string in CP1252 format. But if I set console encoding by going to Run Config->Common Tab and set console encoding as UTF-8, I can see UTF-string properly in the recieved email. I using google server for this test:

Not working: 日本 : Partner Name: アストラゼãƒ?ã‚«æ ªå¼?会社 :

Working: 日本 : Partner Name: アストラゼネカ株式会社

My Code: final String username = "xxxxx@gmail.com"; final String password = "xxxxxx";

    Properties props = new Properties();
    props.put("mail.smtp.host", "smtp.gmail.com");
    props.put("mail.smtp.socketFactory.port", "465");
    props.put("mail.smtp.socketFactory.class",
            "javax.net.ssl.SSLSocketFactory");
    props.put("mail.smtp.auth", "true");
    props.put("mail.smtp.port", "465");

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

    try {
        File fileDir = new File("c:\\new1.txt");

        BufferedReader in = new BufferedReader(
           new InputStreamReader(
                      new FileInputStream(fileDir), "UTF-8"));

        String str;
        String str1 ="";

        while ((str = in.readLine()) != null) {
            str1 += str;
        }

        Message message = new MimeMessage(session);
        MimeMultipart mp = new MimeMultipart();
        message.setFrom(new InternetAddress("xxxxx@gmail.com"));
        message.setRecipients(Message.RecipientType.TO,
            InternetAddress.parse("xxxx@xxxxx.com"));
        message.setSubject(str1);
        MimeBodyPart body = new MimeBodyPart();
        body.setContent("This is a Test EMail. Please ignore", "text/html");
        body.setDisposition(MimeBodyPart.INLINE);
        mp.addBodyPart(body);
        byte[] attachmentData = str1.getBytes();
        DataHandler dh = new DataHandler(new ByteArrayDataSource(attachmentData,"application/octet-stream"));
        MimeBodyPart attachment = new MimeBodyPart();
        attachment.setDataHandler(dh);
        attachment.setDisposition(MimeBodyPart.ATTACHMENT);
        attachment.setFileName("new1.txt");
        mp.addBodyPart(attachment);

        message.setContent(mp);
        Transport.send(message);

        System.out.println("Done");

thanks Madhu

Following are the code changes I made in my J2EE app. In this it is adding 3 files as attachments. One of the 3 files is the subject itself. In the attachment (Subject.txt) conent is fine.

    MimeMessage message = new MimeMessage(s);

    ....

    message.setSubject(subject,"UTF-8");// MimeUtility.encodeText(subject,"UTF-8", "B"));

    ...

            MimeBodyPart body = new MimeBodyPart();
            body.setContent(sm.getMailBody(), "text/html; charset=UTF-8");
            body.setDisposition(MimeBodyPart.INLINE);
            mp.addBodyPart(body);

The debug message. I could not add it as text

Answer 1

Subject would need to be encoded using MimeUtility.encodeText() .

But as Bill Shannon pointed out: Don't do this by encoding it manually, call MimeMessage.setSubject(String subject, String charset) instead. Otherwise setSubject will internally encode resulting string with platform encoding which might cause trouble.

One more thing:

    byte[] attachmentData = str1.getBytes();

Retrieves bytes in platform encoding - which might not be utf-8. Try

    byte[] attachmentData = str1.getBytes(Charset.forName("utf-8"));

Answer 2

将Message声明为MimeMessage，然后使用setSubject方法允许您指定字符集 。