JSP生成彩色验证码

来源：互联网发布：北京联通网络测速编辑：程序博客网时间：2024/04/30 19:28

程序代码ValidateCode.jsp

<%@ page language="java" contentType="image/jpeg" pageEncoding="utf-8"%>
<%@ page import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
<%
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>生成彩色验证码</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>

    <%! //给定范围获得随机颜色
          private 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);
          }
   %>
   <% //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=69, height=26;
          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(Color.WHITE);
          g.fillRect(0, 0, width, height);
          //设定字体
          g.setFont(new Font("隶书",Font.ITALIC,27));
          //画边框
          g.setColor(Color.BLUE);
          g.drawRect(0,0,width-1,height-1);
          //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(0,50));
          for (int i=0;i<15;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);
          }

//取随机产生的认证码(4位数字)
String sRand = "";

         char[] rand={'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z',
  'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','1','2','3','4','5','6','7','8','9'};
         for (int i=0;i<4;i++) {

String s = String.valueOf(rand[random.nextInt(60)]);

                // 将认证码显示到图象中
               g.setColor(new Color(20 + random.nextInt(100),60 + random.nextInt(140),80 + random.nextInt(160)));
               //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(s,15*i+6,21);
               sRand += s;
         }

         //将认证码存入SESSION
         session.setAttribute("rand",sRand);
         //图象生效
         g.dispose();
         //输出图象到页面
         out.clear();
         out = pageContext.pushBody();
         ImageIO.write(image, "JPEG", response.getOutputStream());
    %>
</html>

使用验证码图片的文件a.jsp

<%@ page contentType="text/html;charset=gb2312" %>

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

<body>

<table>

<tr>

<td align=left>系统产生的认证码：</td>

</tr>

<tr>

<td align=left>输入上面的认证码：</td>

</tr>

<tr>

</tr>

</table>

</form>

</body>

</html>

验证的页面check.jsp

<%@ page language="java" import="java.sql.*" errorPage="" %>

<body>
<%

String rand = (String)session.getAttribute("rand");
String input = request.getParameter("rand");

系统产生的认证码为：<%= rand %><br>

您输入的认证码为：<%= input %><br><br>

<%if(rand.equals(input)){ %>

<%}else{%>
<font color=red>输入不同，认证失败！</font>

<%}%>

</body>

</html>