jsp验证码

jsp验证码 <;%@ page contentType=";image/jpeg"; %>; <;%@ page import=";java.awt.*,java.awt.image.*"; %>; <;%@ page import=";java.util.*,javax.imageio.*"; %>; <;%! //产生随机颜色函数getRandColor Color getRandColor(int fc,int bc){ Random r = new Random(); if(fc>;255) fc=255; if(bc>;255) bc=255; int red=fc+r.nextInt(bc-fc); //红 int green=fc+r.nextInt(bc-fc); //绿 int blue=fc+r.nextInt(bc-fc); //蓝 return new Color(red,green,blue); } %>; <;% //设置页面不缓存 response.setHeader(";Pragma";,";No-cache";); response.setHeader(";Cache-Control";,";no-cache";); response.setDateHeader(";Expires";, 0); //创建随机类 Random r = new Random(); // 在内存中创建图像，宽度为width，高度为height int width=60, height=20; BufferedImage pic = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 获取图形上下文环境 Graphics gc = pic.getGraphics(); // 设定背景色并进行填充 gc.setColor(getRandColor(200,250)); gc.fillRect(0, 0, width, height); //设定图形上下文环境字体 gc.setFont(new Font(";Times New Roman";,Font.PLAIN,18)); // 随机产生200条干扰直线，使图像中的认证码不易被其他程序探测到 gc.setColor(getRandColor(160,200)); for (int i=0;i<;200;i++){ int x1 = r.nextInt(width); int y1 = r.nextInt(height); int x2 = r.nextInt(15); int y2 = r.nextInt(15); gc.drawLine(x1,y1,x1+x2,y1+y2); } //随机产生100个干扰点，使图像中的验证码不易被其他分析程序探测到 gc.setColor(getRandColor(120,240)); for (int i=0;i<;100;i++) { int x = r.nextInt(width); int y = r.nextInt(height); gc.drawOval(x,y,0,0); } // 随机产生4位数字的验证码 String RS=";";; String rn=";";; for(int i=0;i<;4;i++){ //产生10以内随机数字rn rn=String.valueOf(r.nextInt(10)); RS+=rn; //将认证码用drawString函数显示到图像里 gc.setColor(new Color(20+r.nextInt(110),20+r.nextInt(110),20+r.nextInt(110))); gc.drawString(rn,13*i+6,16); } // 释放图形上下文环境 gc.dispose(); // 将认证码RS存入SESSION中共享 session.setAttribute(";random";,RS); // 输出生成后的验证码图像到页面 ImageIO.write(pic, ";JPEG";, response.getOutputStream()); %>;