Serve PDF in Spring Portlet MVC Architecture - Liferay 6.0.6 - spring-mvc

Question

I was looking for a way to send a PDF (direct display) file to the browser through Liferay Portal. Found many solutions - the most popular one being writing a Servlet that does the job. I've read about Portlet Resource Serving in JSR 286 Specification, can someone please elaborate on that for Spring 3.0 Portlet MVC?
<servlet>
<display-name>DownloadServlet</display-name>
<servlet-name>DownloadServlet</servlet-name>
<servlet-class>com.liferay.portal.pdf.DownloadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>DownloadServlet</servlet-name>
<url-pattern>/DownloadServlet/*</url-pattern>
</servlet-mapping>
And the Servlet Consists of:
private void downloadServlet(HttpServletRequest req,
HttpServletResponse resp) throws ServletException, IOException {
logger.debug(" downloadServlet :: ");
BufferedInputStream bis = null;
BufferedOutputStream bos = null;
ServletOutputStream op = null;
try {
//Something
pdfContentVO=//getpdf VO here
String filename = "PDFFILE_"+pdfNumber+".pdf";
op = resp.getOutputStream();
resp.setContentType("application/pdf");
resp.setHeader("Content-Disposition", "attachment; filename="
+ filename);
resp.setContentLength(pdfContentVO.getPdfData().length);
System.out.println("pdfcontent"+pdfContentVO.getPdfData());
op.write(pdfContentVO.getPdfData());
op.flush();
op.close();
} catch(final IOException e) {
System.out.println ( "IOException." );
throw e;
} finally {
if (bis != null)
{
bis.close();
}
if (bos != null)
{
bos.flush();
bos.close();
}
}
}

Answer 1

I couldn't find anything on Servlet<->Portlet mapping thing. So I used Resource mapping for sending a pdf with Spring Portlet MVC using annotations.
Ref:http://developers.sun.com/portalserver/reference/techart/jsr286/jsr286_2.html
In JSP:
<portlet:resourceURL var="PDFActionURL">
<portlet:param name="reportType" value="pdf" />
<portlet:param name="pdfNumber" value="${pdfNumber}" />
</portlet:resourceURL>
<input type="button" name="viewPDFButton" value="View PDF" onClick="self.location = '${PDFActionURL}';" />
In Spring ApplicationContext.xml of the portlet, include these:
<context:annotation-config />
<context:component-scan base-package="com.xxx" />
Define a new controller:
import java.io.IOException;
import java.io.OutputStream;
import javax.portlet.PortletException;
import javax.portlet.ResourceRequest;
import javax.portlet.ResourceResponse;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.portlet.bind.annotation.ResourceMapping;
import com.xxx.pdf.PDFBO;
import com.xxx.PDFDTO;
import com.liferay.portal.kernel.servlet.HttpHeaders;
import com.liferay.portal.kernel.util.ParamUtil;
#Controller("pdfController")
#RequestMapping(value = "view")
public class PDFController {
private final static Logger LOG = LoggerFactory.getLogger(PDFController.class);
//This is using Spring 3.0 Annotation Mapping (Spring Portlet MVC Architecture)
#ResourceMapping
public void serveResource(ResourceRequest resourceRequest, ResourceResponse res) throws PortletException, IOException {
LOG.info("In serveResource: ResourceURL");
String returnType = ParamUtil.getString(resourceRequest, "reportType");
String pdfNumber = ParamUtil.getString(resourceRequest, "pdfNumber");
LOG.info("returnType:" + returnType + " pdfNumber:" + pdfNumber);
String filename = "FILENAME_"+pdfNumber+".pdf";
// HttpServletRequest request =
// PortalUtil.getHttpServletRequest(resourceRequest);
if (returnType != null && returnType.equals("pdf")) {
try {
//GET YOUR PDF HERE
//PDFBO pdfBO = new PDFBO();
//PDFDTO pdfContentVO = null;
//pdfContentVO = pdfBO.getPDF(pdfNumber);
res.setContentType("application/pdf");
res.addProperty(HttpHeaders.CACHE_CONTROL, "max-age=3600, must-revalidate");
res.addProperty(HttpHeaders.CONTENT_DISPOSITION,"filename="+ filename);
//Use this to directly download the file
//res.addProperty(HttpHeaders.CONTENT_DISPOSITION,"attachment");
OutputStream out = res.getPortletOutputStream();
//out.write(pdfContentVO.getPdfData());
out.write(/*get pdf byte[] Array Here */);
out.flush();
out.close();
} catch (Exception e) {
LOG.info("Error in " + getClass().getName() + "\n" + e);
}
}
}
}
Edit: If you are using previous versions of Liferay, this is a great article to implement file download/serving through Liferay - https://www.liferay.com/web/raymond.auge/blog/-/blogs/801426