生成随即验证码 -

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生成随即验证码

JSP Java Cache SQL Web

image.jsp-------------------生成随即验证码图片的jsp页面
代码如下：
<%@   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);
}
%>
<%
out.clear();//这句针对resin服务器，如果是tomacat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());
%>

login.jsp--------------------登录页面，在这里我是提供输入验证码然后提交进行验证
代码如下：
<%@   page   language="java"   import="java.sql.*"   errorPage=""   %>
<html>
<head>
<meta   http-equiv="Content-Type"   content="text/html;   charset=gb2312">
<title>用户登录</title>
<script   language="javascript">
      function   loadimage(){
          document.getElementById("randImage").src   =   "image.jsp?"+Math.random();
      }
      </script>
</head>

<body>

<table   width="256"   border="0"   cellpadding="0"   cellspacing="0">
      
      <form   action="validate.jsp"   method="post"   name="loginForm">
      <tr>
          <td   width="118"   height="22"   valign="middle"   align="center"><input   type="text"   name="rand"   size="15"></td>
          <td   width="138"   valign="middle"   align="center"><img   alt="code..."   name="randImage"   id="randImage"   src="image.jsp"   width="60"   height="20"   border="1"   align="absmiddle"></td>
      </tr>
      <tr>
          <td   height="36"   colspan="2"   align="center"   valign="middle"><a   href="javascript:loadimage();"><font   class=pt95>看不清点我</font></a></td>
      </tr>
      <tr>
          <td   height="36"   colspan="2"   align="center"   valign="middle"><input   type="submit"   name="login"   value="提交"></td>
      </tr>
      </form>
</table>
</body>
</html>

validate.jsp-------------用来验证输入的验证码是否正确
代码如下：
<%@   page   contentType="text/html;   charset=gb2312"   language="java"   import="java.sql.*"   errorPage=""   %>
<%
String   rand   =   (String)session.getAttribute("rand");
String   input   =   request.getParameter("rand");
if(rand.equals(input)){
out.print("<script>alert('验证通过！');</script>");
}   else{
out.print("<script>alert('请输入正确的验证码！');location.href='login.jsp';</script>");
}
%>

以上这三个jsp页面放在和WEB-INF相同的目录下，如果你放在不同的文件夹下，那么里面相关页面的路径你就要自己改了。
------------------------------------------------------------------------------------------------------------
先前我给出的image.jsp页面是生成4位随即数字，楼上有朋友也说想要随即出现数字和字母的验证码

以下是我修改的image.jsp的全部源代码：
<%@   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);
}
%>
<%
out.clear();//这句针对resin服务器，如果是tomacat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(10);
int   yl   =   random.nextInt(10);
g.drawLine(x,y,x+xl,y+yl);
}

char   c[]   =   new   char[62];

for   (int   i   =   97,   j   =   0;   i   <   123;   i++,   j++)   {
c[j]   =   (char)   i;
}
for   (int   o   =   65,   p   =   26;   o   <   91;   o++,   p++)   {
c[p]   =   (char)   o;
}
for   (int   m   =   48,   n   =   52;   m   <   58;   m++,   n++)   {
c[n]   =   (char)   m;
}
String   sRand="";
for   (int   i=0;i<4;i++){
int   x   =   random.nextInt(62);
String   rand=String.valueOf(c[x]);
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.setUseCache(true);
ImageIO.write(image,   "JPEG",response.getOutputStream());
%>