问题
My application has to send a textfile, which it first has to generate as a String. The text contains non-ASCII symbols, so i would like it to be UTF-8. I've tried a lot of variants, but all i receive as the attachment is some question marks. And, when i send the same text as the message body, it works all right.
Here is the line of code that generates the MimeBodyPart with the attachment:
String attachment = "Привет";
messageBodyPart.setContent(new String(attachment.getBytes("UTF-8"),
"UTF-8"),"text/plain; charset=UTF-8");
I also tried using the string without any transformations, using just the bytes, now, as you see, i am trying to generate a string from the bytes...
What am i doing wrong? (And i do remember doing this in another project, which works, but i no longer have the access to its source code).
Thank you in advance. Timofey.
UPDATE
Having read your replies, and after some more unsuccessful experimenting i thought it best to publish the code of my mailing thing. I have the Mailer class, which does the mailing, and other classes can just call its static sendMessage() method to send a message. And it all runs on Google App Engine.
public static void sendMessage(String to, String subject, String msgBody,
String attachment) throws AddressException, MessagingException {
Properties props = new Properties();
Session mailSession = Session.getDefaultInstance(props, null);
Message msg = new MimeMessage(mailSession);
String email = "bla-bla-bla"; // userService.getCurrentUser().getEmail();
msg.setFrom(new InternetAddress(email));
msg.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
InternetAddress[] addresses = { new InternetAddress("bla-bla-bla") };
msg.setReplyTo(addresses);
msg.setSubject(subject);
Calendar cal = Calendar.getInstance();
String fileName = cal.get(Calendar.YEAR) + "_"
+ cal.get(Calendar.MONTH) + "_"
+ cal.get(Calendar.DAY_OF_MONTH) + "_"
+ cal.get(Calendar.HOUR_OF_DAY) + "_"
+ cal.get(Calendar.MINUTE) + "_" + cal.get(Calendar.SECOND)
+ "_" + cal.get(Calendar.MILLISECOND) + ".txt";
// create the message part
MimeBodyPart messageBodyPart = new MimeBodyPart();
// fill message
// Here we should have the msgBody.
// Sending attachment contents for debugging only.
messageBodyPart.setText(attachment + " - 4", "UTF-8", "plain");
Multipart multipart = new MimeMultipart();
multipart.addBodyPart(messageBodyPart);
MimeBodyPart att = new MimeBodyPart();
att.setText(attachment, "UTF-8", "plain");
att.addHeader("Content-Type", "text/plain; charset=UTF-8");
att.setFileName(fileName);
multipart.addBodyPart(att);
// Put parts in message
msg.setContent(multipart);
Transport.send(msg);
}
And the line that calls this thing in another class is:
Mailer.sendMessage("mymail@example.com", "Test", "No body", "Привет, Я кусок текста");
And the raw source of the mail, strangely enough, is (leaving out the seemingly irrelevant headers):
Message-ID: <00163662e7107ccbe3049c1402fb@google.com>
Date: Sat, 12 Feb 2011 11:21:01 +0000
Subject: Pages
From: mymail@example.com
To: mymail@example.com
Content-Type: multipart/mixed; boundary=00163662e7107ccbd4049c1402fa
--00163662e7107ccbd4049c1402fa
Content-Type: text/plain; charset=KOI8-R; format=flowed; delsp=yes
Content-Transfer-Encoding: base64
8NLJ18XULCDxIMvV08/LINTFy9PUwSAtIDQNCg==
--00163662e7107ccbd4049c1402fa
Content-Type: text/plain; charset=US-ASCII; name="2011_1_12_11_21_1_691.txt"
Content-Disposition: attachment; filename="2011_1_12_11_21_1_691.txt"
Content-Transfer-Encoding: base64
Pz8/Pz8/LCA/ID8/Pz8/ID8/Pz8/Pw==
--00163662e7107ccbd4049c1402fa--
I just don't get it, why the charsets are different from what i am trying to set, and where they come from.
回答1:
Set the content type to application/octet-stream:
MimeBodyPart attachmentPart = new MimeBodyPart();
try {
DataSource ds = new ByteArrayDataSource(attachment.getBytes("UTF-8"), "application/octet-stream");
attachmentPart = new MimeBodyPart();
attachmentPart.setDataHandler(new DataHandler(ds));
}
catch (Exception e) {
Logger.getLogger("Blina").log(Level.SEVERE, Misc.getStackTrace(e));
}
attachmentPart.setFileName(fileName);
multipart.addBodyPart(attachmentPart);
// Put parts in message
msg.setContent(multipart);
回答2:
Had similar case, following code solved it:
MimeBodyPart att = new MimeBodyPart();
att.setFileName(MimeUtility.encodeText(fileName));
回答3:
This is a sample code that I use to send files (irrespective on encoding or data structure).
BodyPart fileBodyPart = new MimeBodyPart();
fileBodyPart.setDataHandler(new DataHandler(fileDataSource));
fileBodyPart.setFileName(attachment.getName());
fileBodyPart.setHeader("Content-Type", fileDataSource.getContentType());
fileBodyPart.setHeader("Content-ID", attachment.getName());
fileBodyPart.setDisposition(Part.INLINE);
Where fileDataSource is a javax.activation.DataSource (text file will be in here), and
fileBodyPart.setDisposition(Part.INLINE); (PART.INLINE means datasource is inlined with the message body, just like HTML emails, PART.ATTACHMENT means datasource is an attachment).
Hope this helps.
回答4:
If problem is in file name, rather than in body, following code helped in my (hebrew) case:
MimeBodyPart attachment = new MimeBodyPart();
attachment.setFileName(MimeUtility.encodeText(filename, "UTF-8", null));
回答5:
Give this a try:
String attachment = "Привет";
DataSource ds = new ByteArrayDataSource(attachment, "text/plain; charset=UTF-8");
messageBodyPart.setDataHandler(new DataHandler(ds));
UPDATE: (full example)
import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.mail.Session;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import javax.mail.util.ByteArrayDataSource;
public class Main {
public static void main(String[] args) throws Exception {
String attachment = "Привет";
DataSource ds = new ByteArrayDataSource(attachment, "text/plain; charset=UTF-8");
MimeBodyPart attachmentPart = new MimeBodyPart();
attachmentPart.setDataHandler(new DataHandler(ds));
MimeBodyPart bodyPart = new MimeBodyPart();
bodyPart.setText("Hello this is some text");
MimeMultipart mp = new MimeMultipart("mixed");
mp.addBodyPart(bodyPart);
mp.addBodyPart(attachmentPart);
MimeMessage msg = new MimeMessage((Session)null);
msg.setContent(mp);
msg.writeTo(System.out);
}
}
output:
Message-ID: <1439781957.1.1297366787857.JavaMail.dnault@dnault.local>
MIME-Version: 1.0
Content-Type: multipart/mixed;
boundary="----=_Part_0_1579321858.1297366787792"
------=_Part_0_1579321858.1297366787792
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Hello this is some text
------=_Part_0_1579321858.1297366787792
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: base64
0J/RgNC40LLQtdGC
------=_Part_0_1579321858.1297366787792--
回答6:
This works:
MimeMessage msg = new MimeMessage(session);
msg.setFrom(sendFrom);
msg.setSubject(subject, "utf-8");
msg.setSentDate(new Date());
// create and fill the first message part
MimeBodyPart mbp1 = new MimeBodyPart();
mbp1.setContent(message,"text/plain; charset=UTF-8");
// mbp1.setContent(message,"text/html; charset=UTF-8"); // with this the attachment will fail
// create the Multipart and its parts to it
Multipart mp = new MimeMultipart();
mp.addBodyPart(mbp1);
if (attachment!=null){
// Part two is attachment
MimeBodyPart mbp2 = new MimeBodyPart();
mbp2 = new MimeBodyPart();
DataSource ds = null;
try {
ds = new ByteArrayDataSource(attachment.getBytes("UTF-8"), "application/octet-stream");
} catch (IOException e) {
e.printStackTrace();
}
mbp2.setDataHandler(new DataHandler(ds));
mbp2.addHeader("Content-Type", "text/plain; charset=\"UTF-8\"");
mbp2.addHeader("Content-Transfer-Encoding", "base64");
mbp2.setFileName("attachment.txt");
mbp2.setDisposition(Part.ATTACHMENT);
mp.addBodyPart(mbp2);
}
// add the Multipart to the message
msg.setContent(mp);
msg.saveChanges();
// send the message
Transport.send(msg);
回答7:
One more possibility:
String attachment = "älytöntä";
MimeBodyPart part = new MimeBodyPart();
part.setText(attachment, "UTF-8");
part.setDisposition("attachment");
part.setFileName("attachment.txt");
part.setHeader("Content-Transfer-Encoding", "base64");
part.setHeader("Content-type", "text/plain; charset=utf-8");
来源：https://stackoverflow.com/questions/4960556/javamail-sending-mail-attachment-from-string-encoding-utf-8