jsp验证码（数字+字母）

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JSP JavaScript C C++C#

1.建立Image.jsp文件，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(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);
    System.out.println(sRand);
    g.dispose();
    ImageIO.setUseCache(true);
    ImageIO.write(image, "JPEG", response.getOutputStream());
%>

2.建立验证页面validate.jsp，如下
<%@ page language="java" contentType="text/html; charset=GB2312"
    pageEncoding="GB2312"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB2312">
<title>验证</title>
</head>
<body>
<%!String rand = null;

    String input = null;%>
<%
    rand = (String) session.getAttribute("rand");
    input = request.getParameter("yanzhengma");
%>
验证码为：
<%=rand%>
您的输入为：
<%=input%>
<%
if (rand.equals(input)) {
%>
<font color=green>输入相同，认证成功！</font>
<%
} else {
%>
<font color=red>输入不同，认证失败！</font>
<%
}
%>
</body>
</html>

3.建立登录页面login.jsp 如下
<%@   page language="java" import="java.sql.*" errorPage=""%>
<%
request.setCharacterEncoding("GB2312");
%>
<%@page pageEncoding="GB2312"%>
<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="yanzhengma" 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>

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