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jsp 登陆验证码

2012-02-13 17:48 246 查看

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image.jsp

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<%@ page language="java" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" pageEncoding="utf-8"%>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<base href="<%=basePath%>">

<title>My JSP 'images.jsp' starting page</title>

<meta http-equiv="pragma" content="no-cache">

<meta http-equiv="cache-control" content="no-cache">

<meta http-equiv="expires" content="0">

<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">

<meta http-equiv="description" content="This is my page">



</head>

<body>

<%!

Color getRandColor(int fc,int bc){//给定范围获得随机颜色

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();

//设置页面不缓存

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

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

response.setDateHeader("Expires", 0);

// 在内存中创建图象

int width=60, height=20;

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

// 获取图形上下文

Graphics g = image.getGraphics();

//生成随机类

Random random = new Random();

// 设定背景色

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

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

//设定字体

g.setFont(new Font("Comic Sans MS",Font.PLAIN,18));

// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到

g.setColor(getRandColor(220,240));

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);

}

// 取随机产生的认证码(4位数字)

String sRand="";

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

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

sRand+=rand;

// 将认证码显示到图象中

g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));

//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成

g.drawString(rand,13*i+6,16);

}

// 将认证码存入SESSION

session.setAttribute("rand",sRand);

// 图象生效

g.dispose();

// 输出图象到页面

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

%>

</body>

</html>

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login.jsp 摘出来代码

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function loadimage(){

document.getElementById("randImage").src = "images.jsp?"+Math.random();

}

<tr >

<td width="20%" height="15"><div align="right"><span class="STYLE1">验证码</span></div></td>

<td width="27%" height="15" ><div align="center">

<input type="text" name="rand" id="rand" style="width:55px; height:17px; background-color:#FFFFFF; border:solid 1px #7dbad7; font-size:12px; color:#2087bf" />

</div></td>

<td colspan="2" width="57%" height="15"> <img alt="code..." name="randImage" id="randImage" src="images.jsp" width="60" height="15" border="1" ></td>

</tr>

<tr>

<td height="10" colspan="4" align="center"><a href="javascript:loadimage();"><span class="STYLE1"><font color="red">看不清，换一张</font></span></a></td>

</tr>

<c:if test="${imageResult==1}">

<span class="STYLE1"><font color="red">验证码错误，请重新输入。</font> </span>

</c:if>

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ksuserAction.java

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String rand = request.getParameter("rand");

String imageRand = (String)request.getSession().getAttribute("rand");

if(rand.equals(imageRand)){

imageResult = -1;

return Default();

}else{

imageResult = 1;

return Login();

}

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