为什么pdf下载bij Trinidad fileDownloadActionListener不能用pdf阅读器打开？

Question

我确实从String创建了PDF，该String正在xml format，并作为带有fileDownloadActionListener的trinidad按钮呈现给用户。

我可以先下载 PDF，但无法使用Adobe Reader 等PDF reader打开它 我认为它可能已损坏，但事实并非如此，因为我可以使用Visual Studio Code或任何其他文本编辑器(例如notepad(打开它。

1-为什么我无法使用Adobe Reader打开它？

2-有没有更好的为什么要这样做？

前端：

<h:commandButton id="mehrpdf" value="Download PDF" styleClass="popupButton">
<tr:fileDownloadActionListener filename="mehr.pdf"  contentType="application/pdf; charset=utf-8" method="#{bean.downloadMehr}" />
</h:commandButton>

后端：

public void downloadMehr(FacesContext context, OutputStream out) throws IOException
{
String fetchedXmlMessage = getFetchedXmlMessage();
XmlPrettifier prettifier = XmlPrettifierFactory.getInstance();
prettyXmlMessage = prettifier.makePretty(fetchedXmlMessage);
// alternativ way
File pdfFile = createPdfFromTxt(prettyXmlMessage);
OutputStreamWriter w = new OutputStreamWriter(out, "UTF-8");
w.write(prettyXmlMessage);
w.flush();
}

PDF创建：

public File createPdfFromTxt(String content) throws IOException, DocumentException {
//define the size of the PDF file, version and output file
File outfile = File.createTempFile("mehr", ".pdf");
Document pdfDoc = new Document(PageSize.A4);
PdfWriter.getInstance(pdfDoc, new FileOutputStream(outfile)).setPdfVersion(PdfWriter.PDF_VERSION_1_7);
pdfDoc.open();
//define the font and also the command that is used to generate new paragraph
Font myfont = new Font();
myfont.setStyle(Font.NORMAL);
myfont.setSize(11);
pdfDoc.add(new Paragraph("n"));
// add paragraphs into newly created PDF file
File contentFile = File.createTempFile("content", ".txt");
FileUtils.writeStringToFile(contentFile, content);
BufferedReader br = new BufferedReader(new FileReader(contentFile));
String strLine;
while ((strLine = br.readLine()) != null) {
Paragraph para = new Paragraph(strLine + "n", myfont);
para.setAlignment(Element.ALIGN_JUSTIFIED);
pdfDoc.add(para);
}
pdfDoc.close();
br.close();
return outfile;
}

Answer 1

我确实根据上面命令中提到的内容更改了后端，如下所示，现在我可以使用 PDF 阅读器阅读它。谢谢大家。

public void downloadMehr(FacesContext context, OutputStream out) throws IOException
{
String fetchedXmlMessage = getFetchedXmlMessage();
XmlPrettifier prettifier = XmlPrettifierFactory.getInstance();
prettyXmlMessage = prettifier.makePretty(fetchedXmlMessage);
// create pdf from string
PdfCreator pdfCreator = new PdfCreator( prettyXmlMessage);
File pdfFile = pdfCreator.create();
FileInputStream inStream = new FileInputStream(pdfFile);
byte[] buffer = new byte[4096];
int bytesRead = -1;
while ((bytesRead = inStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, bytesRead);
}
inStream.close();
outputStream.close();
}