纯数字验证码

后台：(code为验证码文本框用户输入，rand为session中图片数字)

String sss=request.getSession().getAttribute("rand").toString();//获取session中的验证码

//判断验证码，code为用户输入的验证码

if("".equals(this.getCode())||!sss.trim().equals(this.getCode()))

{

out

.print("<script>alert('验证码错误！');history.go(-1);</script>");

out.flush();

out.close();

}

*****************************

前台jsp:

<tr>

                <td height="40" class="fontbs">验证码：</td>

                <td>

                <input name="code" type="text" class="inputcode">

                </td>

                <td width="81" align="center">

                <a href="javascript:loadimage();" >

     <img alt="点击刷新"

        name="randImage" id="randImage"

        src="shouye/image.jsp"

        width="76"

        height="33"

        border="1"

       />

</a>

                </td>

              </tr>

js部分：

<script language="JavaScript">

      //刷新验证码

    function loadimage()

     {

           document.getElementById("randImage").src= "shouye/image.jsp?"+Math.random();

     }

</script>

************************************

验证码jsp:

image.jsp

********************

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

java.awt.image.*,java.util.*,javax.imageio.*" pageEncoding="UTF-8"%>

<%!

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);

}

%>

<%

out.clear();//这句针对resin服务器，如果是tomcat可以不要这句

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);

}

// 将认证码存入SESSION

session.setAttribute("rand",sRand);

g.dispose();

ImageIO.write(image, "JPEG", response.getOutputStream());

%>

*******************结束





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