以下代码，将输出一个椭圆，再有问题，我可远程助你。如下：
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/**
*(300,100)(400,100)
*
*/
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class Lipse
{
public static void main(String[] args)
{
new MainFrame();
}
}
class MainFrame extends JFrame implements ActionListener
{
JPanel pane=new JPanel();
JTextField T_a,T_b;
JButton Draw,Show;
JLabel L_a,L_b;
int a,b;
MainFrame()
{
super("DrawLipse Window");
Container con=this.getContentPane();
con.setLayout(null);
pane.setBounds(20,20,850,550);
pane.setBackground(new Color(100,156,200));
con.add(pane);
L_a=new JLabel("请输入长半径:a");
L_a.setBounds(180,580,100,20);
con.add(L_a);
L_b=new JLabel("请输入短半径:b");
L_b.setBounds(180,630,100,20);
con.add(L_b);
T_a=new JTextField();
T_a.setBounds(300,580,50,20);
con.add(T_a);
T_b=new JTextField();
T_b.setBounds(300,630,50,20);
con.add(T_b);
Draw=new JButton("画椭圆");
Draw.setBounds(550,580,90,30);
Draw.addActionListener(this);
con.add(Draw);
Show=new JButton("显示坐标");
Show.setBounds(550,620,90,30);
Show.addActionListener(this);
con.add(Show);
this.addWindowListener(new CloseWindow());
this.setBounds(20,20,900,700);
this.setVisible(true);
this.setResizable(false);
}/*MainFrame()*/
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==Draw)
{
a=Integer.parseInt(T_a.getText().trim());
b=Integer.parseInt(T_b.getText().trim());
Line line=new Line(this);
line.drawLipse(a,b);
}
if(e.getSource()==Show)
{
Graphics g1=this.pane.getGraphics();
g1.setColor(Color.PINK);
g1.drawLine(0,300,920,300);//----x---
g1.drawLine(410,0,410,720);//----y---
g1.dispose();
}
}/*method actionPerformed*/
}
class Line
{
MainFrame jb;
Line(MainFrame jb)
{
this.jb=jb;
}
public void drawLipse(int a,int b)
{
int x,y;
double d1,d2;
x=0; y=b;
d1=b*b+a*a*(-b+0.25);
Graphics g=jb.pane.getGraphics();
g.setColor(Color.red);
g.drawLine(x+410,y+300,x+410,y+300);
g.drawLine(-x+410,-y+300,-x+410,-y+300);
g.drawLine(-x+410,y+300,x+410,-y+300);
g.drawLine(x+410,-y+300,x+410,-y+300);
try
{
while(b*b*(x+1)a*a*(y-0.5))
{
if(d1=0)
{
d1+=b*b*(2*x+3);
x++;
}
else
{
d1+=(b*b*(2*x+3)+a*a*(-2*y+2));
x++;
y--;
}
g.drawLine(x+410,y+300,x+410,y+300);
g.drawLine(-x+410,-y+300,-x+410,-y+300);
g.drawLine(-x+410,y+300,x+410,-y+300);
g.drawLine(x+410,-y+300,x+410,-y+300);
Thread.sleep(30);
}// top of while
}catch(Exception e){}
d2=b*b*(x+0.5)*(x+0.5)+a*a*(y-1)*(y-1)-a*a*b*b;
try
{
while(y0)
{
if(d2=0)
{
d2+=b*b*(2*x+2)+a*a*(-2*y+3);
x++;
y--;
}
else
{
d2+=a*a*(-2*y+3);
y--;
}
g.drawLine(x+410,y+300,x+410,y+300);
g.drawLine(-x+410,-y+300,-x+410,-y+300);
g.drawLine(-x+410,y+300,x+410,-y+300);
g.drawLine(x+410,-y+300,x+410,-y+300);
Thread.sleep(30);
}/* bottom of while*/
}catch(Exception e){}
} /*DrawLipse*/
}
class CloseWindow extends WindowAdapter
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
}
使用 AffineTransform 把Ellipse2D 旋转一下就可以了。
import java.awt.image.BufferedImage;
import java.awt.geom.AffineTransform;
import java.awt.geom.Ellipse2D;
import java.awt.Color;
import java.awt.Shape;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.io.File;
import javax.imageio.ImageIO;
public class DemoPNG {
public static void main(String[] args) throws Exception {
BufferedImage bi = new BufferedImage(600, 800, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = bi.createGraphics();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setPaint(Color.WHITE);
g2d.fillRect(0,0,600, 800);
g2d.setPaint(Color.RED);
Ellipse2D s1 = new Ellipse2D.Double(100, 100, 400, 600);
g2d.draw(s1);
AffineTransform transform = AffineTransform.getRotateInstance(Math.PI/4, 300, 400);
Shape r1 = transform.createTransformedShape(s1);
g2d.fill(r1);
AffineTransform transform2 = AffineTransform.getRotateInstance(Math.PI/2, 300, 400);
Shape r2 = transform2.createTransformedShape(s1);
g2d.draw(r2);
g2d.dispose();
ImageIO.write(bi, "PNG", new File("demo.png"));
}
}
publicclassCircle{圆的半径，privatedoublemRadius，publicCircle(doublemRadius){，this.mRadius=mRadius，}获取圆的周长，publicdoublegetLength，{return2Math.PImRadius，}，获取圆的面积publicdoublegetArea{returnMath.PImRadiusmRadius。这样即可在Java编译椭圆周长的程序。
