深入探索JavaFX编程 - CSDN文库

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"pro javaFX 2 - 一本深入讲解JavaFX技术的专业书籍" 在JavaFX领域，这本书"Pro JavaFX 2"提供了丰富的知识和实践经验，帮助开发者快速掌握这一强大的富客户端开发平台。JavaFX是一种用于创建桌面、移动以及Web应用的现代图形用户界面（GUI）框架，它为Java程序员提供了构建动态、互动且视觉效果丰富的应用程序的能力。书中从第1章"Getting a Jump Start in JavaFX"开始，引导读者进入JavaFX的世界，介绍JavaFX的基本概念、安装和配置环境，以及如何编写第一个JavaFX程序，让读者对JavaFX有初步的认识。第2章"Creating a User Interface in JavaFX"深入讨论了如何使用JavaFX设计和构建用户界面。这包括各种控件的使用，布局管理器，以及事件处理机制，使开发者能够创建出直观、用户友好的应用界面。第3章"Properties and Bindings"讲解了JavaFX中的属性和绑定机制，这是JavaFX中一个强大的特性，允许数据的动态更新和视图与模型之间的实时同步。第4章"Building Dynamic UI Layouts in JavaFX"探讨了如何构建动态的用户界面布局，包括响应式设计，使得应用能够在不同大小和方向的屏幕上自适应显示。第5章"Using the JavaFX UI Controls"详细介绍了JavaFX提供的内置控件，如按钮、文本框、菜单等，并展示了如何自定义和扩展这些控件来满足特定需求。第6章"Collections and Concurrency"涵盖了JavaFX中集合的使用以及并发编程，这对于创建高效、多线程的应用至关重要。第7章"Creating Charts in JavaFX"专门讨论了如何在JavaFX中创建各种图表，如折线图、柱状图和饼图，使数据可视化变得更加容易。第8章"Using the Media Classes"介绍了JavaFX的多媒体支持，包括音频和视频的播放、处理和集成，使得开发者能够创建多媒体应用。第9章"Accessing Web Services"讲述了如何在JavaFX应用中访问和使用网络服务，如SOAP和RESTful API，实现与远程数据的交互。第10章"JavaFX Languages and Markup"探讨了JavaFX脚本语言和标记语言的使用，包括FXML，这是一种用于分离界面设计和业务逻辑的声明式语言。此外，书中的附录"The Visage Language in Depth"深入剖析了一种名为Visage的语言，它可能是JavaFX早期版本中的一部分，或者是一种专为JavaFX设计的特定语言。通过这本书，读者将全面理解JavaFX的技术栈，并有能力创建出功能强大、视觉效果出众的JavaFX应用程序。书中不仅包含了理论知识，还包含了大量的实例代码，是JavaFX开发者的宝贵参考资料。

CHAPTER 1 ■ GETTING A JUMP START IN JAVAFX

13

javafx.scene.image package and the Group class in the javafx.scene package. In both cases, they inherit

from the Node class.

■ Tip We can’t emphasize enough the importance of having the JavaFX API documentation handy while

reading this book. As classes, variables, and functions are mentioned, it’s often a good idea to look at the

documentation to get more information. In addition, this habit helps you become more familiar with what is

available to you in the API.

Displaying Images

As shown in the following code, displaying an image entails using an ImageView instance in conjunction

with an Image instance.

ImageViewBuilder.create()

.image(new Image("http://projavafx.com/images/earthrise.jpg"))

.build(),

The Image instance identifies the image resource and loads it from the URL assigned to its URL

variable. Both of these classes are located in the javafx.scene.image package.

Working with Graphical Nodes as a Group

One powerful graphical feature of JavaFX is the ability to create scene graphs, which consist of a tree of

graphical nodes. You can then assign values to properties of a Group located in the hierarchy, and the

nodes contained in the Group will be affected. In our current example from Listing 1-1, we’re using a

Group to contain a Text node and to clip a specific rectangular region within the Group so that the text

doesn’t appear on the moon or the Earth as it animates upward. Here’s the relevant code snippet:

GroupBuilder.create()

.layoutX(50)

.layoutY(180)

.children(

textRef

)

.clip(

RectangleBuilder.create()

.width(430)

.height(85)

.build()

)

.build()

Notice that the Group is located 50 pixels to the right and 180 pixels down, from where it would have

been located by default. This is due to the values assigned to the layoutX and layoutY variables of the

Group instance. Because this Group is contained directly by the Scene, its upper-left corner’s location is

CHAPTER 1 ■ GETTING A JUMP START IN JAVAFX

15

The layoutX and layoutY properties of the Group just described are examples of our earlier

statement that nodes contained in a Group will be affected by values assigned to properties of the

Group. Another example is setting the opacity property of a Group instance to 0.5, which causes all of

the nodes contained in that Group to become translucent. If the JavaFX API documentation is handy,

look at the properties available in the javafx.scene.Group class. Then look at the properties available in

the javafx.scene.Node class properties, which is where you’ll find the layoutX, layoutY, and opacity

variables that are inherited by the Group class.

Drawing Text

In the previous snippet, notice that several variables are available in the Text class. This particular

example is a little more complicated than the normal use of the Text class. Let’s first look at a typical

case, shown in the following snippet, in which you simply want to draw a string of text characters

somewhere in the scene.

TextBuilder.create()

.layoutX(65)

.layoutY(12)

.textOrigin(VPos.TOP)

.fill(Color.WHITE)

.text("Audio Configuration")

.font(Font.font("SansSerif", FontWeight.BOLD, 20))

.build(),

This snippet, borrowed from the Audio Configuration example in Figure 1-7 and Listing 1-3 later in

this chapter, draws the graphical Text string “Audio Configuration” in a bold Sans Serif font. The font

size is 20, and the color of the text is white.

Referring again to the JavaFX API documentation, notice that the VPos enum (in the javafx.geometry

package) has fields that serve as constants, for example, BASELINE, BOTTOM, and TOP. These control

the origin of the text with respect to vertical locations on the displayed Text:

• The TOP origin, as we’re using it in the previous code snippet, places the top of the

text (including ascenders) at the layoutY position, relative to the co-ordinate space

in which the Text is located.

• The BOTTOM origin would place the bottom of the text, including descenders

(located in a lowercase “g”, for example) at the layoutY position.

• The BASELINE origin would place the baseline of the text (excluding descenders)

at the layoutY position. This is the default value for the textOrigin property of a

Text instance.

While you’re looking at the javafx.scene.text package in the API documentation, take a look at the

font function of the Font class, which is used in the previous snippet to define the font family, weight,

and size of the Text.

CHAPTER 1 ■ GETTING A JUMP START IN JAVAFX

16

Turning back again to the Hello Earthrise example in Listing 1-1, we’re using some additional

properties of the Text class that enable it to flow from one line to the next:

• The wrappingWidth property enables you to specify at what number of pixels the

text will wrap.

• The textAlignment property enables you to control how the text will be justified. In

our example, TextAlignment.JUSTIFY aligns the text on both the left and right

sides, expanding the space between words to achieve that.

The text that we’re displaying is sufficiently long to wrap and be drawn on the Earth, so we need to

define a rectangular region outside of which that text can’t be seen.

Clipping Graphical Areas

To define a clipping area, we assign a Node subclass to the clip property that defines the clipping shape,

in this case a Rectangle that is 430 pixels wide and 85 pixels high. In addition to keeping the Text from

covering the moon, when the Text scrolls up as a result of animation the clipping area keeps the Text

from covering the earth.

Animating the Text to Make It Scroll Up

When the HelloEarthriseMain program is invoked, the Text begins scrolling up slowly. To achieve this

animation, we’re using the TranslateTransition class located in the javafx.animation package, as shown

in the following snippet from Listing 1-1.

TranslateTransition transTransition = TranslateTransitionBuilder.create()

.duration(new Duration(75000))

.node(textRef)

.toY(-820)

.interpolator(Interpolator.LINEAR)

.cycleCount(Timeline.INDEFINITE)

.build();

...code omitted...

// Start the text animation

transTransition.play();

The javafx.animation package contains convenience classes for animating nodes. This

TranslateTransition instance (created by the TranslateTransitionBuilder class) translates the Text node

referenced by the textRef variable from its original Y position of 100 pixels to a Y position of –820 pixels,

over a duration of 75 seconds. The Interpolator.LINEAR constant is assigned to the interpolator

property, which causes the animation to proceed in a linear fashion. A look at the API docs for the

Interpolator class in the javafx.animation package reveals that there are other forms of interpolation

available, one of which is EASE_OUT, which slows down the animation toward the end of the specified

duration.

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