How to create a file association for Java Applet (in Windows)?

Everybody says that Java applets are dead (and there are talks to revive them with JavaFX 2). But it seems they are still not dead, at least from my point of view - since I maintain an applet for one of my customers.

Basically, that applet processes .svg files. And it would be convenient for user just to do double-click on a file and get the applet to start with that file.

I solved this problem as follows: applet accepts a parameter in it's launch url, and file association in Windows launches Internet Explorer with the file name as parameter in that url. Here's the code to establish such file association: 
assoc .svg=SvgGraphicsFile
ftype SvgGraphicsFile=C:\Program Files\Internet Explorer\iexplore.exe "www.someplace.ru/index.html?file=" "%1"
And this is how I extracted that file name from applet url: 
// first, in our Applet class, we get the url, from which app was launched
val docBase = getDocumentBase()
 
// then, we parse it
object Loader {
  def load(documentBase: String): Boolean = {
    val pattern = "file="
    val i = documentBase.indexOf(pattern)
    if (i > 0) {
      val f = decode(documentBase.drop(i + pattern.size).stripPrefix("\"%20\""))
      println("loading file: %s" format f)
      // load your file
      true
    } else false
  }
  def decode(l: String): String = {
    var a = l.getBytes
    var i = a.indexOf(37)
    while (i != -1) {
      val x = List(a(i+1).toChar,a(i+2).toChar).mkString
      val p = List(int2ubyte(java.lang.Integer.parseInt(x,16)))
      a = patch(a, i, p, 3)
      i = a.indexOf(37)
    }
    new String(a)
  }
  /** Because default Seq's patch method hangs Proguard. And I do not know why. */
  def patch[A : Manifest](s:Array[A], from: Int, patch: Seq[A], replaced: Int): Array[A] = {
    (s.take(from) ++ patch ++ s.drop(from + replaced)).toArray
  }
  def int2ubyte(i:Int) = if (i > 127) (i - 256).toByte else i.toByte
}
That's it. Hope this helps somebody :)

Comments

Post a Comment

Popular posts from this blog

How to create your own simple 3D render engine in pure Java

Image
3D render engines that are nowdays used in games and multimedia production are breathtaking in complexity of mathematics and programming used. Results they produce are correspondingly stunning. Many developers may think that building even the simplest 3D application from scratch requires inhuman knowledge and effort, but thankfully that isn't always the case. Here I'd like to share with you how you can build your very own 3D render engine, fully capable of producing nice-looking 3D images. Why would you want to build a 3D engine? At the very least, it will really help understanding how real modern engines do their black magic. Also it is sometimes useful to add 3D rendering capabilities to your application without calling to huge external dependencies. In case of Java, that means that you can build 3D viewer app with zero dependencies (apart from Java...
Read more

Solving quadruple dependency injection problem in Angular

Angular comes with built-in dependency injection and module management system, but it can get a bit tedious to use when your project grows. Especially if you use RequireJS alongside it (a must for almost any project) and also want to be minification-safe with all those dependency injections. Let's look at a simple example with one module that provides a value and another module that prints that value: // answer.js define(["angular"], function(angular) { angular.module("the.answer") .value("TheAnswer", 42); }); // main.js define(["angular", "the.answer" ], function(angular) { angular.module("main", [ "the.answer" ]) .run([ "TheAnswer" , function( TheAnswer ) { console.log(TheAnswer); }]); }); As you can see, to provide a single dependency to my code, I had to specify it in four places (highlighted in red) - first as RequireJS dependency, then as Angular module dependency,...
Read more

Configuration objects in Scallop

It turned out that spreading type annotations throughout all the code in all places where options are requested is not a good idea. And, of course, it is prone to errors - who likes those type annotations? When using such option parsing libraries, users usually end up creating a big object with fields corresponding to each option: object Conf { var apples:Int = 0 var bananas:Int = 0 } // ... parsing options ... Conf.apples = parser.getOption("option name", ...) Conf.bananas = parser.getOption("other option name", ...) Sure, this works, and usually flexible enough - but why would anybody want to create such boilerplate? And by the way, nobody likes var's in their code :) So in Scallop , I needed to cut down that unnecessary repetition. There are several ways: Create a compiler plugin. The most powerful option. And the least enjoyable - even given the ease of installing a compiler plugin using sbt, I doubt that anybody will install compiler p...
Read more