JavaFX 1.2 迁移指南(英文)

发表于: 2009年06月13日 类别:JAVAFX技术, JavaFX编程
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本文经授权转载自Stephen Chin的英文文章The Definitive 1.2 Migration Guide中文翻译参见这里

Below is the JavaFX 1.2 migration guide written by Stephen Chin. The original article can be found on his blog steveonjava.com. I post his article here for readers who cannot visit Stephen’s blog due to networking problem. Steve, thanks a lot for allowing me to share it here. The Chinese translation can be found here.

The Definitive 1.2 Migration Guide

by Stephen Chin


If you have made it this far, you are a serious JavaFX hacker!  This section covers the most common language, functionality, and API changes that you will encounter when migrating applications from JavaFX 1.1.  If you notice anything that is not covered, feel free to add it in the comments and I will update the guide as appropriate.


General:

  • JavaFX 1.2 is not binary compatible – If you use any jars or third-party JavaFX libraries (such as JFXtras), they must be recompiled for the new release or you will get compilation errors.  Speaking of JFXtras, a new version which has been updated for JavaFX 1.2 is nearly ready, and will be announced here when it is complete!
  • All internal-only APIs are broken – More details broken out by section below, but if you rely on any impl_ or com.sun packages, your code will definitely need to be updated.
  • Linux and Solaris are now supported – This is more of a feature than a migration issue, but if you have users on multiple platforms you can now proudly state that Linux is supported.


Language Changes:

  • No more variable shadowing in nested blocks – It previously was valid to name a variable the same in both the inner and outer block of an expression.  The variable in the inner block would simply replace the one in the outer.  However, this will throw a compiler error in JavaFX 1.2.  The fix is simple…  just use a different variable name.
  • Use Mixins instead of Multiple Inheritance – JavaFX no longer supports multiple inheritance.  Instead you can extend one class and as many mixins as you like.  Mixins are like interfaces in Java, except they can have variables and implementations that are shared by all the classes that extend them.  The only change you have to make in your application to start using mixins is to add the mixin keyword when you define a new class like this:
public mixin class Resizable { /* variables and functions here */ }
  • Commas are required in sequences – Sequences now require commas between elements (except those that end in braces).  This is a little less convenient, but actually a very good thing, because it avoids several language pitfalls that were hard to track down before.


Node Changes:

  • Node.boundsInScene is gone – This was removed for performance reasons, fortunately there is an easy replacement that offers the same functionality:
node.localToScene(node.boundsInLocal)
  • Node.focusable -> Node.focusTraversable – Small API change, but good to know when you get the compilation error on focusable not found.  This is part of a larger focus fix where any Node that is visible, focusTraversable, and not disabled will be eligible for focus (a key listener is no longer required).
  • CustomNode.create() gets called before init – Previously the CustomNode create() method would get called after init and before postinit.  Now that it gets called even earlier than init, some of your code may not work correctly.  Make sure that any variables you are depending upon in the create() method are either initialized inline or have a bind declaration so they get updated once set.
  • SwingControl.enabled -> Node.disable – There is a new disable flag on the Node class that is used universally across all controls to enable or disable them.  This conflicted with the old SwingControl.enabled variable, which has now been removed.
  • Rectangle2D -> Bounds – All references to Rectangle2D have been changed to the new javafx.geometry.Bounds class, which may have a ripple effect through your code.


Layout Changes:


  • min/max/pref -> getters – All of the Resizable methods (minimumWidth, minimumHeight, maximumWidth, maximumHeight, preferredWidth, preferredHeight) have been replace with function getters (getMinWidth, getMinHeight, getMaxWidth, getMaxHeight, getPrefWidth, getPrefHeight respectively).  The prefWidth/Height functions take an extra parameter, which is the amount of space in the opposite dimension.  This is very useful for doing height or width constrained layouts, such as Flows, but can be ignored by passing -1.
  • impl_layoutX/Y -> layoutX/Y – The impl_layoutX and impl_layoutY methods have been replaced with official layoutX and layoutY variables.  It is recommended that you use these variables over translateX/Y if you are moving nodes into position.
  • impl_requestLayout() -> requestLayout() – The requestLayout function has similarly moved from an internal to a public API.
  • impl_layout -> doLayout() – Rather than having a function to set the layout on, you now override Parent.doLayout().
  • Panel class added for declarative layouts – If you are looking for a functional alternative to Container, take a look at the new Panel class, which lets you set the layout declaratively.  It also has variables to override the default min/max/pref values without subclassing Container.
  • New functions on Container to help with layouts – There are a whole slew of new functions on the Container class that make it easier to work with the new layout system.  Make sure to read through them, because they will both save you time and help you follow the best practices for layout design.
  • Different transformation order – Previously the transforms[] variable allowed you to apply transformations included in the layoutBounds, while scaleX/translateX/rotate etc. were applied after layout.  Now both transforms[] and the transformation variables are calculated after layout uniformly.


Skin/Control Changes:


  • Skin.scene -> Skin.node – The name of the Node on Skin has changed from scene to node, which helps reduce confusion with the Scene class.
  • Skin.compute* methods removed – There were a series of computePreferredWidth/Height/etc. methods that were removed.  Instead you can directly use the getPrefWidth/Height/etc. methods on the Resizable class mentioned above.
  • Skin is now abstract – The Skin class is now abstract, and required that you implement your own contains and intersects methods.  You can either do this by using the new JFXtras AbstractSkin class or using the following boilerplate code:
override function contains(localX:Number, localY:Number):Boolean {
    return node.contains(localX, localY);
}

override function intersects(localX:Number, localY:Number,
   localWidth:Number, localHeight:Number):Boolean {
    return node.intersects(localX, localY, localWidth, localHeight);
}
  • New Behavior class – There is a new Behavior class that is meant to be used together with Control and Skin to provide reusable behaviors.
  • TextBox.text -> rawText, TextBox.value -> text – There was some swizzling of variables on the TextBox class.  What used to be text changed to rawText, and value now has the same semantics text used to have.


Asynchronous Changes:


  • RemoteTextDocument has been removed – Use HttpRequest directly instead.
  • AbstractAsyncOperation has been removed – Use the new Task infrastructure instead for communcating with Java code running in a background thread.


Animation Changes:


  • Transition.interpolate -> Transition.interpolator – A small name change to make room for a new interpolate flag that allows you to turn on or off interpolation altogether.
  • Transition now extends Timeline - This is a welcome change, which makes it much easier to work with Transitions and Timelines together.  To support this change ParallelTransition and SequentialTransition now take a sequence of Timeliens.


Java Equivalent Functions:

  • java.lang.Math -> javafx.util.Math – There is a new JavaFX math library, which is a drop-in replacement for the Java math library.  The main advantage of using the new JavaFX math library is that all functions are supported on mobile devices (including pow, log, etc.).
  • java.lang.Properties -> javafx.util.Properties – Another class that is similar in functionality to the Java equivalent, but portable to mobile.  Be warned, however, that the JavaFX properties file format is not the same as the standard Java properties file format.


CSS Changes:

  • CSS Update Defect (RT-4817) – Stylesheet updates no longer affect newly added Nodes due to a known defect.  In the meantime, you can do this to force a stylesheet refresh:
def senators = bind model.senators on replace {
    delete sceneRef.stylesheets;
    sceneRef.stylesheets = "{__DIR__}styles.css";
}
  • CheckBoxSkin.textFill doesn’t accept styles (RT-4819) - The check mark will pick up the style you set, but the text won’t.  The workaround for now is to create a checkbox with empty text and add a text node beside it with the correct styling and event handlers.
  • Can’t update the skin property of Control from CSS (RT-4820) – Another bug in the skin support.  You can set this in code instead for now.


Production Suite:

  • UiStub -> FXDNode – UiStub has been replaced with FXDNode, which includes some extra functionality, such as backgroundLoading, and placeholder images.


Miscellaneous:

  • Image.fromBufferedImage() removed – This has moved to SwingUtils.toFXImage().  Remember that if you use this function it will limit portability to mobile devices.
  • Color.fromAWTColor() removed – Yet another AWT-ism that has been removed. The JavaFX Color class is pretty thorough, so there shouldn’t be any reason to work with AWT Colors.
  • Duration.toDate is gone – As far as I know there is no equivalent functionality, but you can always get a duration’s value as a long and manipulate it directly.
  • Different variable names for the Affine class – If you use the Affine class, then your code is likely to break due to the new, more descriptive, method names, but the functionality is the same.


Whew!  …that was quite a lot to take in.  If you are interested to read more about the JavaFX 1.2 release including the new controls, layouts, and other functionality, the best source is to checkout the Pro JavaFX book that Jim, Dean, Weiqi, and I are writing.  It is almost fully updated for the JavaFX 1.2 release, and is available in Alpha right now from the book website.


I want to give a special thanks to Richard Bair and Amy Fowler from the Sun JavaFX team for providing a lot of valuable information on the JavaFX 1.2 release along the way.

Happy hacking on JavaFX 1.2!

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