Send an email using javax.mail using your existing InputStream as attachment content

Question

Is it possible to send an email with javax.mailand use the "existing" InputStreamfor the contents of email attachments?

I am currently creating an email message as follows:

final MimeMessage message = new MimeMessage(session);
message.setFrom(new InternetAddress(from));
message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
message.setSubject("Subject line");

final Multipart multipartContent = new MimeMultipart();

    final MimeBodyPart textPart = new MimeBodyPart();
    textPart.setText("Message body");
    multipartContent.addBodyPart(textPart);

    final MimeBodyPart attachmentPart = new MimeBodyPart();
    final DataSource source = new InputStreamDataSource("text/plain", "test.txt", new ByteArrayInputStream("CONTENT INPUT STREAM".getBytes()));
    attachmentPart.setDataHandler(new DataHandler(source));
    attachmentPart.setFileName("text.txt");
    multipartContent.addBodyPart(attachmentPart);

message.setContent(multipartContent);

InputStreamDataSource implemented as follows:

public class InputStreamDataSource implements DataSource
{
    private final String contentType;
    private final String name;
    private final InputStream inputStream;

    public InputStreamDataSource(String contentType, String name, InputStream inputStream)
    {
        this.contentType = contentType;
        this.name = name;
        this.inputStream = inputStream;
    }

    public String getContentType()
    {
        return contentType;
    }

    public String getName()
    {
        return name;
    }

    public InputStream getInputStream() throws IOException
    {
        System.out.println("CALLED TWICE: InputStreamDataSource.getInputStream()");
        return new BufferedInputStream(inputStream);
        //return new ByteArrayInputStream("THIS 'NEW' INPUT STREAM WORKS BUT 'EXISTING' INPUT STREAM RESULTS IN ZERO-BYTE ATTACHMENT".getBytes());
    }

    public OutputStream getOutputStream() throws IOException
    {
        throw new UnsupportedOperationException("Not implemented");
    }
}

DataSourceprovides a method getInputStream()to retrieve InputStreamfor the content of an attached email message.

If I return the “new” InputStream, which is independent of the “existing,” InputStreamthen it works fine. But if I return the "existing" InputStream, then the email will be delivered with a zero byte.

javax.mail "" InputStream ?

Answer 1

InputStream mime, javax.mail.internet.MimeBodyPart(InputStream). DataSource.

, InputStream , javax.mail.internet.MimeBodyPart(InternetHeaders, byte[]) .

Answer 2

:

. https://community.oracle.com/thread/1590625

TL; DR a ByteArrayDataSource

---

Oracle... https://java.net/projects/javamail/sources/mercurial/content/mail/src/main/java/javax/mail/internet/MimeBodyPart.java

java mail 2 :

• , "Content-Transfer-Encoding" 7-8 (. 7 8 )
• ,

... , ( , MB ) ... , "" .

---

" ", , - :

attachmentPart.setDataHandler(new DataHandler(source));
attachmentPart.setHeader("Content-Transfer-Encoding", "8bit");
attachmentPart.setHeader("Content-Type", ds.getContentType() + "; " + ds.getName());

... , ... - setDataHandler invalidateContentHeaders, "Content-Transfer-Encoding" (wtf?!)

, , hooray!!!: D...:( .

---

...

. . ?!. java- , InputStream LineOutputStream, . . java- .:/

Answer 3

InputStream Base64.

//get file name
String fileName = ...;
//get content type
String fileContentType = ...;
//get file content
InputStream fileStream = ...;

//convert to byte array
byte[] fileByteArray = IOUtils.toByteArray(fileStream);
//and convert to Base64
byte[] fileBase64ByteArray = java.util.Base64.getEncoder().encode(fileByteArray);

//manually define headers
InternetHeaders fileHeaders = new InternetHeaders();
fileHeaders.setHeader("Content-Type", fileContentType + "; name=\"" + fileName + "\"");
fileHeaders.setHeader("Content-Transfer-Encoding", "base64");
fileHeaders.setHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");

//build MIME body part
MimeBodyPart mbp = new MimeBodyPart(fileHeaders, fileBase64ByteArray);
mbp.setFileName(fileName);

//add it to the multipart
multipart.addBodyPart(mbp);

Answer 4

I use this code to send email with a downloaded web application. You can easily edit it for your purpose. In mimeType, use the mime type of your application. Happy coding.

try {

        Message message = new MimeMessage(session);
        message.setFrom(new InternetAddress(
                "[e-mail]"));
        message.setRecipients(Message.RecipientType.TO,
                InternetAddress.parse("[e-mail]"));
        message.setSubject("subject");

        Multipart multipart = new MimeMultipart();

        URL url = new URL(url);

        InputStream is = url.openStream();
        MimeBodyPart bodyPart = new MimeBodyPart(is);

        multipart.addBodyPart(bodyPart);

        message.setContent(multipart);
        message.addHeader("Content-Type", mimeType);
        Transport.send(message);
        logger.info("SENT to" + message.getRecipients(RecipientType.TO));

    } catch (MessagingException e) {
        //some implementation
    }