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分析程序探测到
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());
%>;