在服务器上存储文件的同时下载文件？ 如何将文件的下载功能提供给客户端以在服务器上存储文件？

Question

I am using jasper reports in my liferay portlet and I want that user download the reports directly from the output stream. I don't want to store the reports pdf file on my server.

How can I do this with the jasper report?

File pdf = File.createTempFile("output.", ".pdf");
JasperExportManager.exportReportToPdfStream(jasperPrint, new FileOutputStream(pdf));

Right now I'm doing this which generate pdf file in some directory and then I provide download link to user. But I want that user just download the pdf from direct ouptut stream.

Answer 1

In your portlet action:

public void serveResource(ResourceRequest request,ResourceResponse response) throws PortletException, IOException {

    response.setContentType("application/application-download");
    response.setProperty("Content-disposition", "attachement; filename=<some file.pdf>");

    OutputStream responseStream = response.getPortletOutputStream();

    jasperPrint=...
    JasperExportManager.exportReportToPdfStream(jasperPrint, responseStream);

    responseStream.flush();
    responseStream.close();

}

Then create the resource download url like this:

<a href="<portlet:resourceURL/>">Download Report</a>

Answer 2

If I understood the question correctly you coud try

  ByteArrayOutputStream bous = new ByteArrayOutputStream();
  JasperExportManager.exportReportToPdfStream(jasperPrint, bous);
  byte[] bytes = bous.toByteArray();