<%@ page language="java" contentType="image/jpeg" import="java.util.*,java.awt.*,java.awt.image.*,javax.imageio.*" pageEncoding="UTF-8"%><%!//给定范围获得随机颜色Color getRandColor(int fc,int bc){Random random=new Random();if(fc>255) fc=255;if(bc>255) bc=255;int r=fc+random.nextInt(bc-fc);int g=fc+random.nextInt(bc-fc);int b=fc+random.nextInt(bc-fc);return new Color(r,g,b);}%><%//设置页面不缓存response.setHeader("Pragma","No-cache");response.setHeader("Cache-Control","no-cache");response.setDateHeader("Expires",0);//在内存中创建图象int width=60;int height=20;BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);//获取图形上下文Graphics g=image.getGraphics();//生成随机类Random random=new Random();//设置背景色g.setColor(getRandColor(200,250));g.fillRect(0,0,width,height);//字体 g.setFont(new Font("Times New Roman",Font.PLAIN,18));//随机产生155条干扰线，使图像中的验证码不易被其它程序探测到g.setColor(getRandColor(160,200));for(int i=0;i<155;i++){int x=random.nextInt(width);int y=random.nextInt(height);int xl=random.nextInt(12);int yl=random.nextInt(12);g.drawLine(x,y,x+xl,y+yl);}//画出随机产生的四位数字的验证码String sRand="";for(int i=0;i<4;i++){String rand=String.valueOf(random.nextInt(10));sRand+=rand;g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));g.drawString(rand,13*i+6,16);}//存sessionsession.setAttribute("rand",sRand);g.dispose();//输出图像到页面上ImageIO.write(image,"JPEG",response.getOutputStream());out.clear();out=pageContext.pushBody();%>
