Switching from C to Java with Spring/Struts shouldn't be that hard, because you are still on the safe side (the server). The real fun with web technologies starts when you are in the browser.
So if you have no prior experience with the web-technologies, I would recommend you to learn a bit of HTML/CSS/JS until you are familiar with them (build a simple, plain HTML page, add some CSS to change the layout, throw in some JS to load some content asynchronously and maybe add some JS buttons to make the page interactive via JS (e.g. change the content when pressing a button)). Nothing too fancy, just make should you know what every language looks like and which language to use for what use-case.
Next, you should find out which Java Framework you really need to learn. When I learned Struts 2 a couple of years ago, I remember that it was considered outdated already.
And then start doing the tutorials of the frameworks, followed by building something you want to build with those technologies (start small and keep adding stuff). At least that is the path of the self-taught developer.
So if you have no prior experience with the web-technologies, I would recommend you to learn a bit of HTML/CSS/JS until you are familiar with them (build a simple, plain HTML page, add some CSS to change the layout, throw in some JS to load some content asynchronously and maybe add some JS buttons to make the page interactive via JS (e.g. change the content when pressing a button)). Nothing too fancy, just make should you know what every language looks like and which language to use for what use-case.
Next, you should find out which Java Framework you really need to learn. When I learned Struts 2 a couple of years ago, I remember that it was considered outdated already.
And then start doing the tutorials of the frameworks, followed by building something you want to build with those technologies (start small and keep adding stuff). At least that is the path of the self-taught developer.