学步园

 1.松树：

import java.awt.*; 
import java.applet.*; 
public class Tree extends Applet
{ 
	public void paint(Graphics g)
	{ 
		g.drawString("静听松声寒!!", 35, 50 ); 
		tree(200.0,400.0,200.0,0.0,7,g); 
		this.setSize(500,500);
	} 
	public void tree(double x1,double y1,double x2,double y2,int n,Graphics g) 
	{ 
	        if(n>=1)
	        {    
	        	double x3,x4,y3,y4; 
	        	g.drawLine((int)(x1),(int)(y1),(int)(x2),(int)(y2));	
	        	x3=(x1+x2)/2; 
	        	y3=(y1+y2)/2; 
	        	tree(x1,y1,x3,y3,n-1,g); 
	        	tree(x3,y3,x2,y2,n-1,g); 
	        	
	        	x4=(x2+y2-y3-x3)*0.7071+x3; 
	        	y4=(y2-x2+x3-y3)*0.7071+y3; 
	        	tree(x3,y3,x4,y4,n-1,g);        	
	        	x3=(x1*3+x2)/4; 
	        	y3=(y1*3+y2)/4; 
	        	
	        	x2=(x2*3+x1)/4; 
	        	y2=(y2*3+y1)/4; 
	        	x4=(x2*1.732-y2+2*x3-x3*1.732+y3)/2; 
	        	y4=(x2+y2*1.732-x3+2*y3-1.732*y3)/2; 
	        	tree(x3,y3,x4,y4,n-1,g); 	
	        } 
	} 
} 

2.四叶玫瑰线

import java.awt.*;
import java.applet.*;

public class E extends Applet {
	public void paint(Graphics g) {
		g.setColor(Color.green);
		g.setFont(new Font("Serif", Font.PLAIN, 50));
		g.drawString("四叶玫瑰线", 300, 500);
		this.setSize(800, 600);
		for (int i = 5; i < 200; i += 10) {
			for (int j = 0; j < 800; j++) {
				double r;
				int x, y;
				r = i * Math.sin(j * Math.PI / 200);
				x = 150 + (int) (r * Math.cos(j * Math.PI / 400));
				y = 200 + (int) (r * Math.sin(j * Math.PI / 400));
				g.drawLine(x, y, x, y);
				r = i * Math.cos(j * Math.PI / 200);
				x = 500 + (int) (r * Math.cos(j * Math.PI / 400));
				y = 200 + (int) (r * Math.sin(j * Math.PI / 400));
				g.drawLine(x, y, x, y);
			}
		}
	}
}

3.方

import java.awt.*; 
public class D extends java.applet.Applet 
{ 
	public void paint(Graphics g) 
	{ 
		recursquare(300,300,150,0,7,g); 
		this.setSize(650,650);
	} 
	public void recursquare(int x,int y,int r,int dir,int n,Graphics g) 
	{ 
		square(x,y,r,g); 
		if(n>0) 
		{ 
			if(dir!=1) 
			recursquare(x,y-r,r/2,3,n-1,g); 
			if(dir!=2) 
			recursquare(x+r,y,r/2,4,n-1,g); 
			if(dir!=3) 
			recursquare(x,y+r,r/2,1,n-1,g); 
			if(dir!=4) 
			recursquare(x-r,y,r/2,2,n-1,g); 
		} 
	} 
	public void square(int x,int y,int r,Graphics g) 
	{
		g.drawLine(x-r/2,y-r/2,x+r/2,y-r/2); 
		g.drawLine(x-r/2,y-r/2,x-r/2,y+r/2); 
		g.drawLine(x-r/2,y+r/2,x+r/2,y+r/2); 
		g.drawLine(x+r/2,y-r/2,x+r/2,y+r/2); 
	} 
}

4.旋转图

import java.awt.*;
import java.applet.*;

public class A extends Applet {
	public void paint(Graphics g) {
		p(0, 0, 200, g, 14);
		this.setSize(500, 500);
		g.setColor(Color.green);
		g.setFont(new Font("Serif", Font.PLAIN, 50));
		g.drawString("旋转图", 300, 490);
	}

	public void p(int x0, int y0, int r, Graphics g, int n) {
		int x1, y1, x2, y2, x3, y3, x4, y4, x5, y5, x6, y6, x7, y7, x8, y8;
		x1 = x0 - r;
		y1 = y0 + r;
		x5 = x0;
		y5 = y0 + r;
		x2 = x0 + r;
		y2 = y0 + r;
		x6 = x0 + r;
		y6 = y0;
		x3 = x0 + r;
		y3 = y0 - r;
		x7 = x0;
		y7 = y0 - r;
		x4 = x0 - r;
		y4 = y0 - r;
		x8 = x0 - r;
		y8 = y0;
		a(x1, y1, x5, y5, x0, y0, x8, y8, n, g);
		a(x5, y5, x2, y2, x6, y6, x0, y0, n, g);
		a(x8, y8, x0, y0, x7, y7, x4, y4, n, g);
		a(x0, y0, x6, y6, x3, y3, x7, y7, n, g);
	}

	public void a(int x1, int y1, int x2, int y2, int x3, int y3, int x4,
			int y4, int n, Graphics g) {
		g.drawLine(200 + x1, 200 - y1, 200 + x2, 200 - y2);
		g.drawLine(200 + x2, 200 - y2, 200 + x3, 200 - y3);
		g.drawLine(200 + x3, 200 - y3, 200 + x4, 200 - y4);
		g.drawLine(200 + x4, 200 - y4, 200 + x1, 200 - y1);
		if (n <= 1)
			return;
		int xx1, yy1, xx2, yy2, xx3, yy3, xx4, yy4;
		xx1 = (int) ((5 * x1 + x2) / 6);
		yy1 = (int) ((5 * y1 + y2) / 6);
		xx2 = (int) ((5 * x2 + x3) / 6);
		yy2 = (int) ((5 * y2 + y3) / 6);
		xx3 = (int) ((5 * x3 + x4) / 6);
		yy3 = (int) ((5 * y3 + y4) / 6);
		xx4 = (int) ((5 * x4 + x1) / 6);
		yy4 = (int) ((5 * y4 + y1) / 6);
		a(xx1, yy1, xx2, yy2, xx3, yy3, xx4, yy4, n - 1, g);
	}
}

5.视觉冲击

import java.awt.*;
import java.applet.Applet;

public class C extends Applet {
	public void paint(Graphics g) {
		carpet(300, 300, 600, 0, g);
		this.setSize(600, 600);
	}

	public void carpet(int x0, int y0, int r, int n, Graphics g) {
		int x1, x2, y1, y2;
		x1 = x0 + (int) (1 * r / 3);
		x2 = x0 - (int) (1 * r / 3);
		y1 = y0 + (int) (1 * r / 3);
		y2 = y0 - (int) (1 * r / 3);
		g.fillRect(x0 - (int) (r / 6), y0 - (int) (r / 6), (int) (r / 3),
				(int) (r / 3));
		if (n < 6) {
			carpet(x2, y2, (int) (r / 3), n + 1, g);
			carpet(x0, y2, (int) (r / 3), n + 1, g);
			carpet(x1, y2, (int) (r / 3), n + 1, g);
			carpet(x2, y0, (int) (r / 3), n + 1, g);
			carpet(x1, y0, (int) (r / 3), n + 1, g);
			carpet(x2, y1, (int) (r / 3), n + 1, g);
			carpet(x0, y1, (int) (r / 3), n + 1, g);
			carpet(x1, y1, (int) (r / 3), n + 1, g);
		}
	}
}