调用Google Visualization API服务器端

Question

I'm working on a project that involves exporting some HTML reports on a website into PDF format. I'd like to use the excellent flying-saucer Java library to do this but my major stumbling block is that several of these reports use the Google Visualization API to generate charts with JavaScript. Flying-saucer doesn't currently support parsing/executing JS, so those charts don't show up in the generated PDF file.

I was hoping to work around this by seeing if there was some kind of web service I could call instead via server-side code that would return the chart image in Base64 as a variable that I could reference in my view instead of getting it via JS.

The old Google Image Charts API is exactly what I'm looking for, but it has unfortunately been deprecated and it looks like it's slated to be removed completely by next year, so it's not an option.

I'm hoping Google has a newer alternative. If not, is there some other method that's recommended? Thanks!

Answer 1

You can call the getImageURI method of the chart to generate an image/octet stream URI. You can send that data to your server, and you should be able to reconstruct the chart as a .png image file. I've never tried to do this server-side, so I'm not sure precisely how you would go about it, but this java tutorial might be of some assistance to you: http://www.programcreek.com/2009/02/java-convert-image-to-byte-array-convert-byte-array-to-image/

Answer 2

Years ago I wrote Eastwood Charts which implemented the Google Image Charts API as a servlet, backed by JFreeChart , so that you could generate charts without having to rely upon Google, or send your data to their servers. :-)

I don't maintain Eastwood Charts anymore (like Google, I can't be relied upon either) but it is open source and the code works so you might find it helpful. You could also modify it to meet your own requirements, which is something that wasn't possible with the Google service.