<%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %> <%! Color getRandColor(int fc,int bc){//给定范围获得随机颜色 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, 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();
// 设定背景色 g.setColor(getRandColor(200,250)); g.fillRect(0, 0, width, height);
//设定字体 g.setFont(new Font("Times New Roman",Font.PLAIN,18));
//画边框 //g.setColor(new Color()); //g.drawRect(0,0,width-1,height-1);
// 随机产生155条干扰线,使图象中的认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); }
// 取随机产生的认证码(4位数字) String sRand=""; for (int i=0;i<4;i++){ String rand=String.valueOf(random.nextInt(10)); sRand+=rand; // 将认证码显示到图象中 g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//调用函数出来的颜色相同,可能是因为种子太接近,所以只能直接生成 g.drawString(rand,13*i+6,16); }
// 将认证码存入SESSION session.setAttribute("rand",sRand);
// 图象生效 g.dispose();
// 输出图象到页面 ImageIO.write(image, "JPEG", response.getOutputStream());
%> |