jsp实现简单验证码的方法
本文实例讲述了jsp实现简单验证码的方法。分享给大家供大家参考。具体如下：
这里只有一个文件，可以在<img/>的src属性里直接调用显示，适用于各种项目的表单安全验证
jsp页面代码：
<%@pagecontentType="image/jpeg"import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"%>
<%!
ColorgetRandColor(intfc,intbc){
Randomrandom=newRandom();
if(fc>255)fc=255;
if(bc>255)bc=255;
intr=fc+random.nextInt(bc-fc);
intg=fc+random.nextInt(bc-fc);
intb=fc+random.nextInt(bc-fc);
returnnewColor(r,g,b);
}
%>
<%
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires",0);
intwidth=60,height=20;
BufferedImageimage=newBufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
Graphicsg=image.getGraphics();
Randomrandom=newRandom();
g.setColor(getRandColor(200,250));
g.fillRect(0,0,width,height);
g.setFont(newFont("TimesNewRoman",Font.PLAIN,18));
g.setColor(getRandColor(160,200));
for(inti=0;i<155;i++){
intx=random.nextInt(width);
inty=random.nextInt(height);
intxl=random.nextInt(12);
intyl=random.nextInt(12);
g.drawLine(x,y,x+xl,y+yl);
}
StringsRand="";
for(inti=0;i<4;i++){
Stringrand=String.valueOf(random.nextInt(10));
sRand+=rand;
g.setColor(newColor(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
g.drawString(rand,13*i+6,16);
}
session.setAttribute("rand",sRand);
g.dispose();
ImageIO.write(image,"JPEG",response.getOutputStream());
response.getOutputStream().flush();
response.getOutputStream().close();
out.clear();
out=pageContext.pushBody();
%>
希望本文所述对大家的JSP程序设计有所帮助。