Off Topic - Database object retrieval
I'm afraid this is a bit off topic - but I'm posting here in the hope that someone may have tackled a similar problem...
The major requirement of the project I'm currently working on is that of storing arbitrary file based data in a database. The data stored can potentially be any valid file: .pdf, .htm, .xls, .docx, .mp3, .zip, .exe etc.
Storage of any file type is no problem.using <rich:fileUpload/> and an appropriate listener.
Retrieval of some of these objects is however problematic in some cases; the following code works just fine for .pdf, .htm, .doc, .xls where the appropriate client side application (IE, word, excel etc.) is launched and opens the document. This method does not however work for all file types (mp3, .exe) since IE (and probably other browsers) does not know how to handle the 'pushed' data stream despite being told the mime type.
public String actionOpenDocument() {
HttpServletRequest request = AppUtils.getCurrentRequest();
// this if required to prevent unwanted execution of the method
if ((request.getParameter("AJAXREQUEST") == null) || request.getParameter("AJAXREQUEST").isEmpty()) {
String docid = request.getParameter("docid"); // get docid
DocumentDao dao = new DocumentDao(); // database access methods
Document doc = dao.retrieveDocumentById(docid); // get the document
FacesContext fc = FacesContext.getCurrentInstance();
HttpServletResponse response = AppUtils.getCurrentResponse();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
try {
SerializableBlob sblob = (SerializableBlob) doc.getFdata(); // serialise doc data
Blob blob = sblob.getWrappedBlob();
// get stream from Blob
InputStream inStream = blob.getBinaryStream();
int length = -1;
byte[] buffer = new byte[4096];
// write data to output stream
while ((length = inStream.read(buffer)) != -1) {
baos.write(buffer, 0, length);
}
baos.flush();
MimetypeDao mDao = new MimetypeDao();
Mimetype mt = mDao.retrieveMimetypeById(doc.getMimetype_id()); // gets mime type on basis of file extention
response.setContentType(mt.getMimetype());
response.setContentLength(baos.size());
ServletOutputStream outStream = response.getOutputStream();
baos.writeTo(outStream);
baos.flush();
outStream.flush();
outStream.close();
inStream.close();
} catch (Exception ex) {
ex.printStackTrace();
}
fc.responseComplete();
}
return null;
}
<h:commandLink id="openlink" style="color: #ffffff;" target="#{document.fname}" immediate="false" action="#{ProductBean.actionOpenDocument}" >
<h:graphicImage alt="#{document.fname}" url="#{document.mimetype.icon}" />
<f:param name="docid" value="#{document.id}" ></f:param>
</h:commandLink>
What I'm seeking, is suggestions for how to handle the 'problem' file types...
Any help / suggestions greatly appreciated.
