RE: struts and iText

Tue, 03 Aug 2004 06:41:02 -0700

Another option: write the PDF out to a database BLOB field, then create an Action to retrieve that field. This I think gives you the best of all worlds. If you structure the table properly, you can share the PDF across various requests/users and you can even avoid PDF generation potentially by seeing if an appropriate PDF exists in the table already. A simple timed stored procedure should serve as a good cleanup mechanism. Just to save you some time, here's an Action I use in a system I wrote that retrieves any BLOB field and returns it... I'll have to remove some parts and just give you comments because it uses two custom classes for database access, and I don't want to post that much code here, the other classes are a bit larger... I'll also simplify the error handling, since it's custom as well, but I think the point will come across... The only note I think is that this assumes that the table the BLOB is retrieved from has a field with the same name as the BLOB field with _ctype appended, and this contains the content type to return.


import java.io.ByteArrayOutputStream;
import java.sql.Blob;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletOutputStream;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

public class BLOBServerAction extends Action {

public ActionForward execute(ActionMapping mapping, ActionForm inForm, HttpServletRequest request, HttpServletResponse response) throws Exception {

   try {

     String bTable = "the_table_the_blob_is_in";
     String bField = "the_field_the_blob_is_in";
     String bQuery = "where_clause_to_select_proper_record;

String sql = "select " + bField + "," + bField + "_ctype from " + bTable + " where " + bQuery;
Blob blob = null;
String contentType = null;
byte[] bytes = null;

ResultSet rs = doSelect(sql); // Insert database access here, just use the above constructed SQL string
while (rs.next()) {
contentType = rs.getString(bField + "_ctype");
blob = rs.getBlob(bField);
}

     ServletOutputStream out = response.getOutputStream();

     response.setContentType(contentType);
     if (blob != null) {
       bytes = blob.getBytes(1, (int)(blob.length()));
       ByteArrayOutputStream ba = new ByteArrayOutputStream();
       ba.write(bytes, 0, bytes.length);
       ba.writeTo(out);
     }
     out.flush();

   } catch (Exception e) {

     e.printStackTrace();

   }

   return null;

 } // End process()

}


Hope that helps, if you go this route.

Frank W. Zammetti
Chief Software Architect
Omnytex Technologies
www.omnytex.com


From: "Jesse Alexander (KXT)" <[EMAIL PROTECTED]>
Reply-To: "Struts Users Mailing List" <[EMAIL PROTECTED]>
To: Struts Users Mailing List <[EMAIL PROTECTED]>
Subject: RE: struts and iText
Date: Tue, 3 Aug 2004 10:49:08 +0200

Well,...

If you already have the PDF generated, why not directly write it to the response(and in this way to the browser)?

To fulfill your use case as described.
Your action generates the PDF and caches it somewhere. Then it will forward to the JSP-File containing the message and the link. This link either points to a Struts-Action or a plain servlet. This target-Servlet (or Action) retrieves the cached PDF and sends it to the browser.
Where to cache?
a) File-System
- you need a writable location and remember to install some cleaning mechanism
- the link presented could be just the reference to the cached file if that directory
readable by the webserver
b) user-session
- dangerous in a clustered environment (too much stuff to propagate around)
- memory usage (usually the recommendation is not to use more than 4K in session...)
- PDF only available to original user
- easy to program
c) separate cache
- adds another component to your app (DO NOT roll your own cache, there are quite a
number of tested cache-libraries)
- could make the PDF available also to other users (depends on the use-case and the
cache-library)

hope this helps
Alexander


-----Original Message-----
From: Otto, Frank [mailto:[EMAIL PROTECTED]
Sent: Tuesday, August 03, 2004 9:18 AM
To: '[EMAIL PROTECTED]'
Subject: struts and iText

Hi,

I have generated a pdf with iText. In my action class I want to write it in the response object.

The result should be a jsp-page with content "pdf generated successful" and a link to this pdf. The pdf should be shown in a new browser window too.

Has someone do this? How can I do this?


kind regards,

frank

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