[jsp]代码库
<%@ 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);
int green=fc+r.nextInt(bc-fc);
int blue=fc+r.nextInt(bc-fc);
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.setHeader("Expires",0);
//创建随机类
Random r=new Random();
//在内存中创建图像,宽为width,高为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();
//设定背景颜色并进行填充
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="" , rn="";
for(int i=0;i<4;i++){
//产生10以内的随机数字rn
rn=String.valueOf(r.nextInt(10));
RS+=rn;
//将验证码用drawString 函数显示在图像里
gc.drawString(rn , 13*i+6 , 16);
//释放图形上下文环境
gc.dispose();
//将验证码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());
%>