利用ValidateCode jar包实现验证码功能以及登陆时验证码的校正

public class CodeServlert extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            //使用jar生产验证码
        ValidateCode vCode = new ValidateCode(100, 25, 4, 9);
        //获取生产的验证码字符串
         String code =vCode.getCode();
         //传值方式1.拼接网址字符串  2.使用域对象

         //使用session 来储存验证码
         request.getSession().setAttribute("wcode", code);

         System.out.println(code);
         //写到网页上 (通过  响应中的字符流  写回网页)
         vCode.write(response.getOutputStream());
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}

jsp代码

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!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=UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
    function changeCode() {
        //从文档中取出img图片
        var img = document.getElementsByTagName("img")[0];
        //获取图片的src 属性 并赋值
        //注意:如果请求网址完全相同 则浏览器不会帮你刷新
        //可以拼接当前时间  让每次请求的网址都不一样

        img.src = "/SH-web-servlet04/code?time "+ new Date().getTime();
    }
</script>
</head>   <!-- com.lanou3g.code.Dologin -->

    <%
        // 书写java代码 
        //获取 request 域中的数据  
        String msg= (String)request.getAttribute("msg");
        if(msg!=null){
            out.write(msg);
        }



    %>
    <form action="/SH-web-servlet04/dologin" method="post">
        用户名：<input type="text" name="userName"/><br>
        密码：<input type="password" name="pwd"/><br>
        验证码：<input type="text" name="code"/>
        <img src="/SH-web-servlet04/code" onclick="changeCode()"/>
        <a href="javascript:changeCode()">看不清换一张</a>
        <br>
        <input type="submit" value="登录"/><br>
    </form>
</body>
</html>

登陆功能验证码校验功能

public class Dologin extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println(123123);
                    //设置响应编码格式
                    response.setContentType("text/html;charset=UTF-8");
                    //告诉服务器  请求的内容是什么编码格式的
                    request.setCharacterEncoding("UTF-8");

                    //获取到请求过来的参数(表单提交过来的数据)
                String userName = request.getParameter("userName");
                String pwd = request.getParameter("pwd");
                String code = request.getParameter("code");
                //获取域中的session 
                HttpSession session = request.getSession();
                String  wcode = (String)session.getAttribute("wcode");
                PrintWriter out = response.getWriter();
                System.out.println(userName + pwd + code);
                // wanglong   123 
                if (userName.equals("wanglong") && pwd.equals("123")) {
                    System.out.println(1230);

                      //判断验证码(忽略大小写)
                    if (!code.equalsIgnoreCase(wcode)) {
                        //提示用户  验证码有误
                        //把错误信息  从 dologin 页面传到 1.jsp页面上
                        //使用request域 保存 验证码错误的信息
                        request.setAttribute("msg", "验证码输错了");
                        //请求转发
                        request.getRequestDispatcher("/1.jsp").forward(request, response);
                    }
                }else {
                    //提示登陆失败
                    //2秒回登陆页面  
                    response.getWriter().write("登陆失败");

                }


    }

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}

利用ValidateCode jar包实现验证码功能 以及登陆时验证码的校正

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利用ValidateCode jar包实现验证码功能以及登陆时验证码的校正