Question

Certain Vaadin addons, such as Invient Charts (https://vaadin.com/directory#addon/invient-charts), require the inclusion of javascript libraries to operate.

How can this be done without having to create a custom Servlet for Vaadin applications?

Answer 1

Using the Scaladin addon and the Scala language, this is accomplished by the following code in the init() method on your application:

override def init() {
  super.init()

  // bring in javascript needed for addons
  val jqsrc = io.Source.fromInputStream(getClass.getResourceAsStream("/js/jquery-1.4.4.min.js"))
  val hcsrc = io.Source.fromInputStream(getClass.getResourceAsStream("/js/highcharts.js"))
  val xpsrc = io.Source.fromInputStream(getClass.getResourceAsStream("/js/modules/exporting.js"))
  mainWindow.executeJavaScript((jqsrc ++ hcsrc ++ xpsrc).mkString)
  jqsrc.close(); hcsrc.close(); xpsrc.close() }

Note that the javascript files being opened as InputStreams must be in the classpath. To do this using SBT, make a resources directory under the src/main dir, and put the /js dir and the .js files within. These will be put into the WEB-INF/classes dir when the war file is built. They will also appear in the classpath when you use container:start from the xsbt web plugin, so the same code allows for testing prior to making the .war file.

This approach should be able to work without Scala (but with a lot more Java code), but what fun would that be?

A more efficient way would be to load the JavaScript code into a string held in an object to avoid having to repeatedly read it in:

object Script {
  val js = Seq("/js/jquery-1.4.4.min.js", "/js/highcharts.js", "/js/modules/exporting.js") map { f =>
    val in = io.Source.fromInputStream(getClass.getResourceAsStream(f))
    val s = in.mkString
    in.close()
    s
  }
}

and then in the Vaadin Application:

class MyApp extends Application(title = "My App", applicationTheme = "reindeer")  {
  override def init() {
    super.init()

    // bring in javascript needed for addons
    Script.js foreach mainWindow.executeJavaScript
  }
.
.
.