GSF is based on mimetypes. Each GSF language plugin is associated
with a particular "mime type". For example, Ruby files have the
mime type text/x-ruby, JavaScript files have the mime
type text/javascript, and so on.
In order for GSF to add its editing services to particular files, you have to teach the IDE how to recognize the mime type for your files. You do that using the "mime resolver" support in NetBeans. This is not particular to GSF, but it's a prerequisite.
Basically, all you have to do is write a simple XML file which
tells NetBeans for example that files with the extension .foo
have the mimetype text/foo. Once you've done that,
you can go to the registration
section and register editing services for the text/foo
mime type. GSF will provide DataLoaders, DataObjects etc. for
files of the mimetypes as soon as you do that.
When you create a new NetBeans plugin, it will typically create an empty layer.xml file for you. This is an XML file where you can register implementations of various IDE services. In particular, to register a mime resolver, you'll need to add something like this:
<filesystem>
<folder name="Services">
<folder name="MIMEResolver">
<file name="javascript.xml" url="jsresolver.xml">
<attr name="SystemFileSystem.localizingBundle" stringvalue="org.netbeans.modules.javascript.editing.Bundle"/>
<attr name="position" intvalue="190"/>
</file>
</folder>
</folder>
<filesystem>
Here, the file name javascript.xml should be something unique that no other
mime resolver might have picked. The url attribute points to a filename
in the same directory as the layer.xml file. I'll cover that file next.
Finally, the attributes let you create a properly localized user visible description
of files of this file type.
For the example above, you would create a Bundle.properties file in the same
package as the layer file (again, when you create a plugin you usually get one of these
created for you already), and it should contain something like this:
Services/MIMEResolver/javascript.xml=JavaScript Files
Finally, you need to go and write the actual mime resolver file, jsresolver.xml
(we could have named it anything, including javascript.xml).
<!DOCTYPE MIME-resolver PUBLIC "-//NetBeans//DTD MIME Resolver 1.0//EN" "http://www.netbeans.org/dtds/mime-resolver-1_0.dtd">
<MIME-resolver>
<file>
<ext name="json"/>
<ext name="js"/>
<resolver mime="text/javascript"/>
</file>
</MIME-resolver>
Here we're saying that files of extensions json and js should
be treated as JavaScript files. The DTD for mime resolvers allow more complex
analysis, such as analyzing file headers and such. Take a look
at the DTD for
the full details. You can also write a custom class to do mime resolvers
if you have really specific needs. Avoid doing that if you can, since with a custom
mime resolver the IDE can't figure out what you're doing and do special optimizations.
There is an example of how to do this in the ruby editing module - look for RubyMimeResolver - but
again try to avoid this if you don't strictly have to do it.
Finally, note that there is a position attribute on the registration of the mime resolver above. The position attributes are used to order the mime resolvers. In case there are overlaps in registrations, order matters. For that reason, pick some number. NetBeans integration unit tests will check all the layers and make sure there aren't inconsistencies into folder orderings and will generate unit test failures if there are.
Once you register your mime type with GSF (described in the registration document, files shown in the Files and Projects views will be handled by GSF. You can also assign a custom icon to file as well as context menu actions. To do this, you need a few more registration steps. Add something like the following to your layer:
<folder name="Loaders">
<folder name="text">
<folder name="javascript">
<attr name="SystemFileSystem.icon" urlvalue="nbresloc:/org/netbeans/modules/javascript/editing/javascript.png"/>
<attr name="iconBase" stringvalue="org/netbeans/modules/javascript/editing/javascript.png"/>
<folder name="Actions">
<file name="OpenAction.instance">
<attr name="instanceClass" stringvalue="org.openide.actions.OpenAction"/>
<attr name="position" intvalue="100"/>
</file>
<file name="Separator1.instance">
<attr name="instanceClass" stringvalue="javax.swing.JSeparator"/>
<attr name="position" intvalue="200"/>
</file>
<file name="CutAction.instance">
<attr name="instanceClass" stringvalue="org.openide.actions.CutAction"/>
<attr name="position" intvalue="300"/>
</file>
<file name="CopyAction.instance">
<attr name="instanceClass" stringvalue="org.openide.actions.CopyAction"/>
<attr name="position" intvalue="400"/>
</file>
<file name="PasteAction.instance">
<attr name="instanceClass" stringvalue="org.openide.actions.PasteAction"/>
<attr name="position" intvalue="500"/>
</file>
<file name="Separator2.instance">
<attr name="instanceClass" stringvalue="javax.swing.JSeparator"/>
<attr name="position" intvalue="600"/>
</file>
<file name="NewAction.instance">
<attr name="instanceClass" stringvalue="org.openide.actions.NewAction"/>
<attr name="position" intvalue="700"/>
</file>
<file name="DeleteAction.instance">
<attr name="instanceClass" stringvalue="org.openide.actions.DeleteAction"/>
<attr name="position" intvalue="800"/>
</file>
<file name="RenameAction.instance">
<attr name="instanceClass" stringvalue="org.openide.actions.RenameAction"/>
<attr name="position" intvalue="900"/>
</file>
<file name="Separator3.instance">
<attr name="instanceClass" stringvalue="javax.swing.JSeparator"/>
<attr name="position" intvalue="1000"/>
</file>
<file name="SaveAsTemplateAction.instance">
<attr name="instanceClass" stringvalue="org.openide.actions.SaveAsTemplateAction"/>
<attr name="position" intvalue="1100"/>
</file>
<file name="Separator4.instance">
<attr name="instanceClass" stringvalue="javax.swing.JSeparator"/>
<attr name="position" intvalue="1200"/>
</file>
<file name="FileSystemAction.instance">
<attr name="instanceClass" stringvalue="org.openide.actions.FileSystemAction"/>
<attr name="position" intvalue="1300"/>
</file>
<file name="Separator5.instance">
<attr name="instanceClass" stringvalue="javax.swing.JSeparator"/>
<attr name="position" intvalue="1400"/>
</file>
<file name="ToolsAction.instance">
<attr name="instanceClass" stringvalue="org.openide.actions.ToolsAction"/>
<attr name="position" intvalue="1500"/>
</file>
<file name="PropertiesAction.instance">
<attr name="instanceClass" stringvalue="org.openide.actions.PropertiesAction"/>
<attr name="position" intvalue="1600"/>
</file>
</folder>
</folder>
</folder>
</folder>
Here, the highlighted section shows how an icon is assigned to this type.
You need to place an icon in the directory shown in the attribute. The rest
of this section registers various common actions you might want on your
files. These are all standard actions defined by NetBeans so you don't
have to write these on your own.