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：





<%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>

<%!

Color getRandColor(int fc,int bc){

  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);

}

%>

<%

response.setHeader("Pragma","No-cache");

response.setHeader("Cache-Control","no-cache");

response.setDateHeader("Expires", 0);

int width=60, height=20;

BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

Graphics g = image.getGraphics();

Random random = new Random();

g.setColor(getRandColor(200,250));

g.fillRect(0, 0, width, height);

g.setFont(new Font("Times New Roman",Font.PLAIN,18)); 

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);

}

String sRand="";

for (int i=0;i<4;i++){

  String rand=String.valueOf(random.nextInt(10));

  sRand+=rand;

  g.setColor(new Color(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。