如何使Swing使用我自己的HTMLEditorKit用于JLabel / JButton / etc

Question

Lets say I've made a sublcass of HTMLEditorKit (and other relevant classes) in order to display some custom HTML tags. I want to be able to to use these custom tags in JLabel , JButton , and so on. Is there any way to do this beside creating my own look-and-feel? That is, I want to tell swing "use this instance of HTMLEditorKit for rendering HTML in JLabel /etc" regardless of what look-and-feel is currently being used. From the little poking around I've done in Swing internals I don't think it's possible, but I'd love to be proven wrong.

Answer 1

It can be done:

The key is in the class javax.swing.plaf.basic.BasicLabelUI , which is a basic UI for labels.

In the paint method, we can see this code:

View v = (View) c.getClientProperty(BasicHTML.propertyKey);
if (v != null) {
    v.paint(g, paintTextR);
}

A BasicHTML class is the supplier of HTML capabilities in Java, so, theoretically, if you replace the client property for BasicHTML.propertyKey with your own implementation of View, then that class will be used and you can do whatever you want to render the text.

The class javax.swing.plaf.basic.BasicLabelUI is the parent of most of other LAF label UIs out there, but not all, so it may not work for all LAFs. LAFs that don't support HTML using the BasicHTML class will not work with your fix, either.

But IMHO this is more of a hack than feature. You are programming againts implementation, not interface. So if you don't have really serious reasons to do that, I would suggest to find a cleaner way to render your custom HTML, such as JLabel subclass.

Answer 2

It can't be done normally . . . If you extend the JLabel and JButton classes, it might be possible, but these seems like a lot of work for something there are better ways to do[1]. Would be useful classes though.

[1]: If the text doesn't need to be dynamic, try using images in JImagesIcons .

Answer 3

Please refer to https://bugs.openjdk.java.net/browse/JDK-6540252
The bug reporter proposes a several workarounds.