How to use wkhtmltopdf in Java web application?

Question

I am newbie in wkhtmltopdf. I am wondering how to use wkhtmltopdf with my Dynamic Web Project in Eclipse? How to integrate wkhtmltopdf with my Java dynamic web application?

Is there any tutorials available for beginners of wkhtmltopdf ?

(Basically, I would like to use wkhtmltopdf in my web application so that when user click a save button , the current page will be saved to PDF file).

Answer 1

First, a technical note: Because you want to use wkhtmltopdf in a web project, if and when you deploy to a Linux server machine that you access via ssh (i.e. over the network), you will need to either use the patched Qt version, or run an X server, e.g. the dummy X server xvfb. (I don't know what happens if you deploy to a server running an operating system other than Linux.)

Second, it should be really quite simple to use wkhtmltopdf from any language in a web project.

If you just want to save the server-generated version of the current page, i.e. without any changes which might have been made like the user filling on forms, or Javascript adding new DOM elements, you just need to have an extra optional argument like ?generate=pdf on the end of your URL, which will cause that page to be generated as a PDF, and then the PDF button will link to that URL. This may be a lot of work to add to each page manually if you are just using simple JSP or something, but depending on which web framework you are using, the web framework may offer some help to implement the same action on every page, if you need to implement that.

To implement this approach, you would probably want to capture the response by wrapping the response object and overridding its getWriter() and getOutputStream() methods.

Another approach is to have a button "submit and generate PDF" which will generate the next page as a PDF. This might make more sense if you have a form the user needs to fill in - I don't know. It's a design decision really.

A third approach is to use Javascript to upload the current state of the page back to the server, and process that using wkhtmltopdf. This will work on any page. (This can even be used on any site, not just yours, if you make it a bookmarklet. Just an idea that occurred to me - it may not be a good idea.)

A fourth approach is, because wkhtmltopdf can fetch URLs, to pass the URL of your page instead of the contents of the page (which will only work if the request was a HTTP GET, or if it's equivalent to a HTTP GET on the same URL). This has some small amount of overhead over capturing your own response output, but it will probably be negligible. You will also very likely need to copy the cookie(s) into a cookie jar with this approach, since presumably your user might be logged in or have an implicit session.

So as you can see there are quite a lot of choices!

Now, the question remains: when your server has the necessary HTML, from any of the above approaches, how to feed it into wkhtmltopdf? This is pretty simple. You will need to spawn an external process using either Runtime.getRuntime().exec(), or the newer API called ProcessBuilder - see http://www.java-tips.org/java-se-tips/java.util/from-runtime.exec-to-processbuilder.html for a comparison. If you are smart about it you should be able to do this without needing to create any temporary files.

One of the wkhtmltopdf websites is currently down, but the main README is available here, which explains the command line arguments.

This is merely an outline answer which gives some pointers. If you need more details, let us know what specifically you need to know.