AWT的层次关系

1、第四章 图形编程4.1AWT与Swing简介一.AWT工具包java的抽象窗口工具包（AWT:Abstract window Interface)包含在java.awt包中，它提供了许多用来设计GUI的组件类和容器类基本AWT库处理用户界面元素的方法是把这些元素的创建和行为委托给每个目标平台上的本地GUI工具箱进行处理AWT的层次关系EventComponentGraphicsMenuComponButtonScrollBarContainerCanvasListCheckBoxLabelTextFieldTextAreaWindowFrameDialogFontAppletPanel二. J

2、ava Swing Swing：非基于对等体的GUI工具箱Swing具有更丰富并且更方便的用户界面元素集合Swing对底层平台的依赖更少Swing会带来交叉平台上的统一视觉体验Swing类被放在javax.Swing包上Swing 组件层次关系ComponemtContainerWindowFrameDialogJFrameJDialogJComponentJPanelJLabelJScrollerJMenuBarJButtonJtext.三.AWT与Swing的关系对于使用过Java早期版本的人来说，大部分AWT组件都有其Swing等价物后者的名字一般是在前面添加一个字母“J”，如：JBut

3、ton,JFrame,JPanel等5.2组件和容器一.组件Java把由Component类的子类或间接子类创建的对象称为一个组件例：Button button1=new Button();例：TextField textfield=new TextField();例：Label label=new Label();二.容器Java把由container类的子类或间接子类创建的对象称为一个容器例：Frame fra=new Frame(“这是一个窗口”)；Applet是Panel的子类，是Container的间接子类Applet本身也是一个容器三.添加组件Component类提供了一个方法：a

4、dd();例：fra.add(button);例：fra.add(TextField);容器本身也可以看作是一个组件，因此可以把一个容器添加到另一个容器里，实现容器嵌套例：add(fra);四。布局管理器Java 采用非常优秀的概念来进行布局一个容器内的所有组件都由一个布局管理器来进行管理Java支持以下四种布局管理器 FlowLayout BorderLayout CardLayout GridBagLayout五.常用容器1.框架在Java中，顶层窗口（没有包含在另一个窗口内的窗口）称为框架AWT库中有一个基于对等体的Frame类对应着顶层该类的Swing版本为JFrame,JFrame是

5、Frame 子类例：框架是容器的例子 SimpleFrameTest.java import javax.swing.*;public class SimpleFrameTest public static void main(String args) SimpleFrame myframe = new SimpleFrame(); myframe.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE); myframe.show(); class SimpleFrame extends JFrame public SimpleFrame() setSi

6、ze(WIDTH, HEIGHT); public static final int WIDTH = 300; public static final int HEIGHT = 200;2.定义相对框架通过调用toolkit来得到系统相关信息例：CenteredFrameTest.java例：获得屏幕尺寸Toolkit kit = Toolkit.getDefaultToolkit(); Dimension screenSize = kit.getScreenSize();int screenHeight=screenSize.height;int screenWidth = screenSi

7、ze.width;class CenteredFrame extends JFrame public CenteredFrame() / get screen dimensions Toolkit kit = Toolkit.getDefaultToolkit Toolkit kit = Toolkit.getDefaultToolkit();(); Dimension screenSize = kit.getScreenSize(); Dimension screenSize = kit.getScreenSize(); int screenHeight = screenSize.heigh

8、t; int screenHeight = screenSize.height; int screenWidth = screenSize int screenWidth = screenSize.width;.width; / center frame in screen/ center frame in screen setSize(screenWidth / 2, screenHeight / 2); setSize(screenWidth / 2, screenHeight / 2); setLocation(screenWidth / 4, screenHeight setLocat

9、ion(screenWidth / 4, screenHeight / 4) / 4) / set frame icon and title / set frame icon and title Image img = kit.getImage(icon.gif); Image img = kit.getImage(icon.gif); setIconImage(img); setIconImage(img); setTitle(CenteredFrame setTitle(CenteredFrame);); 3.常见类及方法APIjava.awt.Componentboolean isVis

10、ible()检查组件是否可见void setVisible(boolean b) 设置组件可见void setBounds(int x,int y,int width,int height)移动并缩放组件Dimension getSize()得到组件的大小void setSize(int width,int height)void setSize(Dimension d) 把组件缩放到指定调度和宽度 java.awt.windowvoid toFrond()放在其它窗口前面void toBack()放在其它窗口后面java.awt.Framevoid setResizable(boolean

11、b)缩放框架void setTitle(String s)设置标题void setIconImage(Image image) 将Image用作图标java.awt.Toolkit Dimension getScreenSize()得到用户屏幕大小内容窗格是用来添加组件的，获得内容窗格的代码如下：在AWT中可调用add()把组件直接添加到AWT Frame中 ,但在Swing中组件只能添加到内容窗格里六.显示信息前面的例子中 ,信息都显示在控制台窗口,现在我们试着把信息显示到JFrame中 JFrame的结构有点复杂，它由：根窗格、布局窗格、透明窗格和内容窗格 用户也可以创建一个画板，然后在画

12、板上进行绘制，最后将画板添加到内容窗格里，此时需要重载paintComponent()paintComponent(Graphics g)是定义在JComponent中，每当该方法被调用时，系统就自动产生一个Graphics类型的参数，传递给paintComponent方法中的参数gContainer cp=getContentPane(); Component c=; cp.add(c);Graphics类提供绘制图像和输出文本的方法创建一个画板class MyPanel extends JPanel public void paintComponent(Graphics g) super.

13、paintComponent(Graphics g) g.drawString(“Hello!world”) . MyPanel扩展了扩展了JPanel,但面板的背景但面板的背景颜色等工作要由颜色等工作要由Jpanel来完成，来完成，super.paintComponent确保父类也参预绘制确保父类也参预绘制只要窗口重新绘制，paintComponent()就被自动调用（在AWT中上paint()例.在画板上输出信息NotHelloWorld.javaclass NotHelloWorldFrame extends JFrameclass NotHelloWorldFrame extends

14、JFrame public NotHelloWorldFrame public NotHelloWorldFrame()() setTitle(NotHelloWorld setTitle(NotHelloWorld); ); setSize setSize(WIDTH, HEIGHT);(WIDTH, HEIGHT); / add panel to frame / add panel to frame NotHelloWorldPanelNotHelloWorldPanel panel = new panel = new NotHelloWorldPanel NotHelloWorldPan

15、el();(); Container contentPane = getContentPane(); Container contentPane = getContentPane(); contentPane contentPane.add(panel); .add(panel); class NotHelloWorldPanel extends JPanel class NotHelloWorldPanel extends JPanel public void paintComponent public void paintComponent(Graphics g)(Graphics g)

16、super.paintComponent super.paintComponent(g);(g); g.drawString g.drawString(Not a Hello, World program, (Not a Hello, World program, MESSAGE_X, MESSAGE_Y); MESSAGE_X, MESSAGE_Y); public static final int public static final int MESSAGE_X = 75; MESSAGE_X = 75; public public static final intstatic fina

17、l int MESSAGE_Y = 100; MESSAGE_Y = 100;常用APIjavax.swing.JFrameContainer getContentPane() 返回JFrame的内容窗格java.awt.Component void repain() 重新绘制组件void repaint(int x, int y,intwidth,int height) 重新绘制组件的一部分javax.swing.Jcomponentvoid paintComponent(Graphics g)需要重载该方法来说明你的组件应如何绘制5.3图形编程一. 2D图形 1.2D对象 随着SDK2.0

18、版的到来，J2SE了包含一个Java 2D库，该库实现了一个非常强大的图形操作集如何获得Graphics 2D类对象该类是Graphics类的子类，通常可用Graphics对象转换而来.例：public void paintComponent(Graphics g) graphics2D g2=(graphics 2D)g; . 2.坐标 JDK 1.0版中使用整数像素坐标系java 2D形体使用浮点数坐标系，这样可为坐标指定单位。存在的问题:Retangle2D r=.; float f=r.getWidth();/*Error*/getWidth()返回double值，应进行转换： flo

19、at f=(float)r.getWidth();例：DrwaTest.java因此，2D库的形体类有两种版本： Retangle2D.Float Retangle2D.Doubleclass DrawPanel extends JPanel public void paintComponent(Graphics g) super.paintComponent(g); Graphics2D g2 = (Graphics2D)g;/ draw a rectangle double leftX = 100; double topY = 100; double width = 200; double

20、 height = 150; Rectangle2D rect = new Rectangle2D.Double(leftX, topY, width, height); g2.draw(rect); / draw the enclosed ellipse Ellipse2D ellipse = new Ellipse2D.Double(); ellipse.setFrame(rect); g2.draw(ellipse);/ draw a diagonal line g2.draw(new Line2D.Double(leftX, topY, leftX + width, topY + he

21、ight); / draw a circle with the same center double centerX = rect.getCenterX(); double centerY = rect.getCenterY(); double radius = 150; Ellipse2D circle = new Ellipse2D.Double(); circle.setFrameFromCenter(centerX, centerY, centerX + radius, centerY + radius); g2.draw(circle); 3.常用APIjava.awt.geom.R

22、etangle2D.DoubleRetangle2D.Float(float x,float y,float width, float height) Ellipse2D.Double(double x,double y, double width,double height)java.awt.geom.Ellipse2D.DoubleRetangle2D.Double(double x,double y, double width,double height)java.awt.geom.Retangle2D.Floatjava.awt.geom.Line2D.DoubleLine2D.dou

23、ble(Point2D start,Point2D end)Line2D.double(double startx,double starty, double endx,double endy)java.awt.geom.Point2D.DoublePoint2D.Double(double x,double y)fill(Graphics2D rec) 填充颜色drawGraphics2D rec) 绘制图形rec二.颜色Graphics2D类的setPaint方法(Graphics类为setColor方法)用来设置颜色。例： g2.setPaint(Color.red); g2.drawS

24、tring(“Set Color”,100,100)1.标准颜色black、blue、cyan、darkgray、gray、green、lightgray、magenta、orange、pink、red、white、yellow2.复合色通过指定红绿蓝三色比例，用Color对象来复合成一种新的颜色。Color构造器如下：Color(int redness,int greenness,int blueness) 其中参数取值为0-2553.常用APIjava.awt.Colorvoid Color(int r,int g,int b)例:g.setPaint(new Color(0,128,12

25、8); java.awt.Graphicsvoid setcolor(Color c)java.awt.Graphic2Dvoid setPaint(paint p) java.awt.Cmponentvoid setBackground(Color c)void setForeground(Color c)例：填充颜色的例子FillTest.javaclass FillPanel extends JPanelclass FillPanel extends JPanel public void paintComponent public void paintComponent(Graphics

26、 g)(Graphics g) super.paintComponent super.paintComponent(g);(g); Graphics2D g2 = (Graphics2D)g; Graphics2D g2 = (Graphics2D)g; / draw a rectangle / draw a rectangle double leftX double leftX = 100; = 100; double topY double topY = 100; = 100; double width = 200; double width = 200; double height =

27、150; double height = 150; Rectangle2D rect Rectangle2D rect = new Rectangle2D.Double = new Rectangle2D.Double (leftX, topY (leftX, topY,width, height);,width, height); g2. g2.setPaintsetPaint(Color.red)(Color.red); ; g2. g2.fillfill(rect(rect);); / draw the enclosed ellipse / draw the enclosed ellip

28、se Ellipse2D ellipse = new Ellipse2D.Double(); Ellipse2D ellipse = new Ellipse2D.Double(); ellipse.setFrame(rect ellipse.setFrame(rect);); g2. g2.setPaintsetPaint(new Color(0, 128, 128);(new Color(0, 128, 128); / a dull blue-green / a dull blue-green g2. g2.fillfill(ellipse);(ellipse); 三.文本和字体1.五个逻辑

29、字体名SanaSerifSerifMonospacedDialogDialogInput2.字体风格Font.PLAIN Font.BOLDFond.ITALIC Fond.BOLD+Font.ITALIC 3.设置字体Font serif=new Font(“Serif”,Font.BOLD,14);g2.setFont(serif);4.编程控制字体字符输出的效果取决于下面三个因素： 使用的字体 字符串 绘制字体的设备几个基本术语： 上坡度下坡度空行 基线基线高度 调用Graphics2D类中的getFontRenderContext方法，可获得一个FontRenderContext类的对

30、象,再调用Fond类的getStringBounds方法,该方法返回一个包围字符串的矩形.代码如下：String message=“Hello,World!”;Font f=new Foun(“serif”,Font.BOLD,14);FontRenderContext context= g2. getFontRenderContext();Retangle2D bounds= f. getStringBounds(message,context);获得字符串宽度、高度、上坡度、下坡度的方法如下：double stringwidth= bounds.getWidth();double stri

31、ngheigth= bounds.getHeigth();double ascent= - bounds.getY();double descent= bounds.getHeigth() +bounds.getY();基点将字符串显示在面板中央的代码如下：String message=“Hello,World!”;Font f=new Foun(“serif”,Font.BOLD,14);FontRenderContext context= g2. getFontRenderContext();Retangle2D bounds= f. getStringBounds(message,con

32、text);double x=(getWidth()- bounds. getWidth()/2;double y=(getHeigth()- bounds.getWidth()/2;double ascent= - bounds.getY();double basey=y+ascent;g2.drawString(message, (int)x,(int)basey);例：将字符串显示在画板中央的例子 FontTest.javaAPI:java.awt.Font Font(String name,int style,int Size)String getFontName()String ge

33、tFamily()String getName()Retangle2D getStringBounds(String s, FountRenderContext context)java.awt.font.LineMetricsfloat getAscent()float getDecent()float getHeight()float getWeight()java.awt.Graphicsvoid setFont(Font font)void DrawString(String str,int x,int y)四.图象在Java应用程序中须通过使用Toolkit对象，调用getDefau

34、ltToolkit()，完成将一个图象文件加载到程序中，再调用Graphics类提供的DrawImage()显示它。目前只能读取gif和JPEG格式的文件下面一段代码用来在本地机上加载一个名为 msn.jpg的文件：Image img=ToolkitgetDefaultToolkit(). getImage(“msn.jpg”)若从网络上加载，必须提供URL例：URL u=new URL( “http:/ img=ToolkitgetDefaultToolkit(). getImage(u)显示代码： public void paintComponent(Graphics g) . g.drawImage(img,x,y,null); 图象的跟踪加载使用MediaTracker类中的方法addImage()可以将一个图象的加载过程放入媒体跟踪器，从而实现对图象加载过程的跟踪MediaTracker tracker=new MediaTracker(); Image img=ToolkitgetDefaultToolkit(). get