java图像界面开发简单实例

Graphics2D、Rectangle2D、Ellipse2D、Line2D的简单应用,原理为创建相应的图形对象，并设置图形的大小及相关设置，通过Graphics2D对象的draw方法将图形对象保存与JPanel面板中，通过Graphics2D对象的setPaint(setColor)方法可以设置相应的填充颜色

import java.awt.*; import java.awt.geom.*; import javax.swing.*; /** *@version 1.0 2011-10-20 *@author Yanghai */ public class DrawFillTest { public static void main(String [] args) { EventQueue.invokeLater(new Runnable() { public void run() { DrawFillFrame frame=new DrawFillFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } }); } } class DrawFillFrame extends JFrame { public DrawFillFrame() { setSize(DEFAULT_WIDTH,DEFAULT_HEIGHT); setTitle("DrawFillTest"); DrawFillComponent component=new DrawFillComponent(); add(component);//将panel添加到frame中 } public final int DEFAULT_WIDTH=400; public final int DEFAULT_HEIGHT=400; } class DrawFillComponent extends JComponent { public void paintComponent(Graphics g) { Graphics2D g2=(Graphics2D) g;//将Graphics对象转换为Graphics2D对象 double leftX=100; double topY=100; double width=200; double heigth=150; /* int leftX=100; int topY=100; int width=200; int heigth=150; Rectangle rect=new Rectangle.Double(leftX,topY,width,heigth); g2.drawRect(rect); */ Rectangle2D rect=new Rectangle2D.Double(leftX,topY,width,heigth); g2.draw(rect); g2.setColor(Color.green); g2.fillRect((int)leftX,(int)topY,(int)width,(int)heigth); //g2.drawArc((int)leftX,(int)topY,(int)width,(int)heigth,0,180); //g2.drawOval((int)leftX,(int)topY,(int)width,(int)heigth); Ellipse2D ellipse=new Ellipse2D.Double(); ellipse.setFrame(rect); g2.draw(ellipse); g2.setPaint(Color.red); g2.fillOval((int)leftX,(int)topY,(int)width,(int)heigth); Line2D line=new Line2D.Double(leftX,topY,leftX+width,topY+heigth); g2.draw(line); double centerX=rect.getCenterX();//定义圆心坐标 double centerY=rect.getCenterY(); int r=150; Ellipse2D circle=new Ellipse2D.Double(); circle.setFrameFromCenter(centerX,centerY,centerX+r,centerY+r); //设置圆形的绘制框架（4个参数表示中心点坐标和角点坐标） g2.draw(circle); g2.setColor(new Color(0,128,128)); g2.fillArc((int)centerX-r,(int)centerY-r,300,300,0,90); } }

此段代码主要练习了如何构建矩形、椭圆、圆、直线以及相应的填充图形的一些知识。
编译效果如下：