javax.mail 附加的 PDF-File 已损坏

Question

我正在开发一个程序，该程序应该通过javax将填充的PDF文件作为附件发送到邮件中。为了进行测试，我将邮件发送到我自己的地址，发送本身工作正常，但附加的PDF文件似乎已损坏。

我的PDF阅读器告诉，该文件可能被错误地解码了。经过一番重新搜索，我添加了行

 filePart.setHeader("Content-Transfer-Encoding", "base64");
 filePart.setHeader("Content-Type", "application/pdf");

到下面的代码，但它仍然不起作用。

try
    {
        String filename = "C:/somerandompath/PDFTest.pdf";
        reader = new PdfReader(filename);
        tempFile = File.createTempFile("FORM" , ".pdf");
        fostream = new FileOutputStream(tempFile);
        stamper = new PdfStamper(reader , fostream);
        acro_fields = stamper.getAcroFields();
        Iterator entries = pdfOutputs.entrySet().iterator();
        while (entries.hasNext())
        {
            Entry thisEntry = (Entry)entries.next();
            acro_fields.setField((String)thisEntry.getKey() , (String)thisEntry.getValue());
        }

        /** Sending the Mail */
        try
        {
            Properties properties = new Properties();
            properties.put("mail.smtp.host" , "servername");
            javax.mail.Session sess = javax.mail.Session.getDefaultInstance(properties , null);
            DataSource fileDataSource = new FileDataSource(tempFile.getAbsolutePath());
            BodyPart filePart = new MimeBodyPart();
            MimeMultipart content = new MimeMultipart();
            MimeBodyPart textPart = new MimeBodyPart();
            String mailtext = "This is a Testmail";
            filePart.setDataHandler(new DataHandler(fileDataSource));
            filePart.setFileName("File.pdf");
            filePart.setHeader("Content-Transfer-Encoding", "base64");
            filePart.setHeader("Content-Type", "application/pdf");
            content.addBodyPart(filePart);
            textPart.setText(mailtext);
            textPart.setHeader("MIME-Version" , "1.0");
            textPart.setHeader("Content-Type" , textPart.getContentType());
            content.addBodyPart(textPart);
            Message msg = new MimeMessage(sess);
            InternetAddress addressFrom = new InternetAddress("[e-mail]");
            InternetAddress addressTo = new InternetAddress("[e-mail]");
            InternetAddress adressCC = new InternetAddress("[e-mail]");
            msg.setFrom(addressFrom);
            msg.setRecipient(Message.RecipientType.TO , addressTo);
            msg.setRecipient(Message.RecipientType.CC, adressCC);
            msg.setSubject("Your file");                
            msg.setContent(content);
            Transport.send(msg);
            properties.clear();
        }
        catch(Exception ex1)
        {
            System.out.println(ex1);
        }
    }
    catch(Exception ex2)
    {
        System.out.println(ex2);
    }

我将不胜感激任何指导

Answer 1

正如 mkl 已经指出的那样，您应该在使用临时文件发送邮件之前关闭PdfStamper实例。现在，根据您共享的代码片段，您的PDF文件已损坏是正常的：您使用的是未完成的PDF。

除此之外，您使用的是临时文件非常奇怪。为什么不在内存中创建文件？做这样的事情：

ByteArrayOutputStream baos = new ByteArrayOutputStream();
PdfStamper stamper = new PdfStamper(reader, baos);
// do stuff with stamper
stamper.close();
byte[] pdf_bytes = baos.toByteArray();

现在，您可以在JavaMail中使用这些字节，如下所述：使用byte[]和Java-Mail发送电子邮件附件