jsp验证码源码

1.<%@ page  import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>  
2.<%@ page import="java.io.OutputStream" %>  
3.<%!  
4.Color getRandColor(int fc,int bc){  
5.Random random = new Random();  
6.if(fc>255) fc=255;  
7.if(bc>255) bc=255;  
8.int r=fc+random.nextInt(bc-fc);  
9.int g=fc+random.nextInt(bc-fc);  
10.int b=fc+random.nextInt(bc-fc);  
11.return new Color(r,g,b);  
12.}  
13.%>  
14.<%  
15.try{  
16.response.setHeader("Pragma","No-cache");  
17.response.setHeader("Cache-Control","no-cache");  
18.response.setDateHeader("Expires", 0);  
19.int width=60, height=20;  
20.BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);  
21.OutputStream os=response.getOutputStream();  
22.Graphics g = image.getGraphics();  
23.Random random = new Random();  
24.g.setColor(getRandColor(200,250));  
25.g.fillRect(0, 0, width, height);  
26. 
27.g.setFont(new Font("Times New Roman",Font.PLAIN,18));  
28.g.setColor(getRandColor(160,200));  
29.for (int i=0;i<155;i++)  
30.{  
31.int x = random.nextInt(width);  
32.int y = random.nextInt(height);  
33.int xl = random.nextInt(12);  
34.int yl = random.nextInt(12);  
35.g.drawLine(x,y,x+xl,y+yl);  
36.}  
37.String sRand="";  
38.for (int i=0;i<4;i++){  
39.String rand=String.valueOf(random.nextInt(10));  
40.sRand+=rand;  
41.g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));  
42.g.drawString(rand,13*i+6,16);  
43.}  
44.session.setAttribute("rand",sRand);  
45.g.dispose();  
46. 
47.ImageIO.write(image, "JPEG",os);  
48. 
49.//注意看以下几句的使用  
50.os.flush();  
51.os.close();  
52.os=null;  
53.response.flushBuffer();  
54.out.clear();  
55.out = pageContext.pushBody();  
56.}  
57.catch(IllegalStateException e)  
58.{  
59.System.out.println(e.getMessage());  
60.e.printStackTrace();  
61.}%>