Belongs to following categories: Utility, ULC5.2, ULC6.1, ULC6.2, UltraLightClient '08,
Project Home
Downloads
Purpose
The intended way how to print from within an ULC application running in
a servlet container is to generate a PDF document on the server-side and
make this document availabe for download by the client. The PDF document
can then be printed like any other PDF document, only depending on the
PDF viewer and installed printers.
In more detail, the PDF document is first generated on the server-side
using session-specific data. The document is then made accessible to the
client via a web server. Finally, the ULC client launches the web
browser and queries the browser to fetch the PDF document from the
respective web server address.
The described printing functionality can also be used to provide the
client with any other kind of dynamically generated resource, e.g. an
Excel document containing session-specific numbers.
The Printing utility works transparently in development mode and no web
server is needed.
How to use
Implement a Web Resource Provider
We first have to decide whether we can generate in-memory the web
resources to be sent to the client. If so, we inherit from
MemoryResourceProvider and implement the abstract
method
createBytes(). Using the PDF library
iText, we can generate in-memory PDF documents like
shown in the simple example below.
public class PdfMemoryProvider extends MemoryResourceProvider{
...
protected byte[] createBytes() throws IOException
{
try {
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
Document document = new Document(PageSize.A4);
PdfWriter writer = PdfWriter.getInstance(document, outputStream);
document.open();
document.add(new Paragraph("Hello ULC!"));
document.close(); writer.flush();
writer.close();
outputStream.close();
return outputStream.toByteArray();
}
catch(DocumentException de)
{
throw new IOException("Could no create PDF document: " + de.getLocalizedMessage());
} }
}
In case we cannot generate the web resource in-memory but only write it
to a file first, we inherit from
FileResourceProvider
and implement the abstract method
getFile(). Using
the PDF library
iText, we can
generate PDF files like shown in the simple example below.
public class PdfFileProvider extends FileResourceProvider
{ ...
protected File createFile() throws IOException
{
try
{
File file = File.createTempFile(getClass().getName(), ".pdf");
file.deleteOnExit(); OutputStream outputStream = new FileOutputStream(file);
Document document = new Document(PageSize.A4);
PdfWriter writer = PdfWriter.getInstance(document, outputStream);
document.open();
document.add(new Paragraph("Hello ULC!"));
document.close(); writer.flush();
writer.close();
outputStream.close();
return file;
}
catch(DocumentException de)
{
throw new IOException("Could no create PDF document: " + de.getLocalizedMessage());
} }
}Register a Web Resource Provider with the Download Manager
Whenever the user wants to print some data, we register an instance of
our web resource provider with the
DownloadManager
using the
put() method and we will receive a
unique id. We can then call the
showDocument()
method and pass it the id. This will cause the ULC client to launch the
browser and download the web resource returned by the corresponding
registered web resource provider.
IResourceProvider pdfProvider = new PdfMemoryProvider(...);String id = DownloadManager.INSTANCE.put(pdfProvider);try
{
DownloadManager.INSTANCE.showDocument(id, "template");
}
catch(IOException ioe)
{
System.err.println("Cannot show document: " + ioe);}Add the Web Resource Download Servlet to the Servlet Context
Now, all that remains to be done is to add the
ResourceDownloadServlet
to the same servlet context as the ULC application that triggered the
printing. Add the configuration below to your
web.xml
file.
<servlet>
<servlet-name>ResourceDownloadServlet</servlet-name> <servlet-class>com.canoo.ulc.community.ulcprinting.application.ResourceDownloadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ResourceDownloadServlet</servlet-name> <url-pattern>/download</url-pattern>
</servlet-mapping>
Compatibility
- ULC 5.2: JDK 1.4.2
- ULC 6.1: JDK 1.4.2
- ULC 6.2: JDK 1.4.2, JDK 1.5, JDK 1.6, Windows XP, Windows
Vista, Linux, Mac OSX
- UltraLightClient 2008: JDK 1.4.2, JDK 1.5, JDK 1.6, Windows
XP, Windows Vista, Mac OSX
Project setup with Eclipse
The project contains all necessary Eclipse project files and can be
directly imported from the repository. The classpath in this project
contains a entry named
ULC Library, which locates
the needed UltraLightClient libraries. For to uses the
ULC
Library entry you have to install the Eclipse Java IDE Integration
Plug-in that can be found at :
http://update.canoo.com/eclipse.
A installation guide how to install plug-ins in Eclipse can be found at
the Eclipse help pages: Workbench User Guide > Tasks > Updating and
installing software.
Project Links
Project Home
Downloads
Author
etienne
