session的登录验证-------工具验证码

index.jsp

<%@ 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=ISO-8859-1">
<title>Insert title here</title>
<script type="text/javascript">
    function changeCode(){
        var img=document.getElementsByTagName("img")[0];
        img.src="/session/ShowCode?random="+Math.random();
    }
</script>
</head>
<body>
    <% 
        String msg=(String)request.getAttribute("msg");
        if(msg!=null){
            out.print(msg);
        }
    %>
    <form action="/session/LoginCheck">
               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="/session/ShowCode" onclick="changeCode()"><a href="javascript:changeCode()">看不清换一张</a></br>
            <input type="submit" value="登录">
    </form>
</body>
</html>

验证登录

package qingxia.tang;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class LoginCheck
 */
@WebServlet("/LoginCheck")
public class LoginCheck extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public LoginCheck() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter pw=response.getWriter();
        String userName = request.getParameter("userName");
        String pwd = request.getParameter("pwd");
        String code = request.getParameter("code");
        //从session中获取code值
        String ycode =(String) request.getSession().getAttribute("ycode");
        if("tom".equals(userName) && "123".equals(pwd)){
            if(!ycode.equalsIgnoreCase(code)){
                request.setAttribute("msg", "验证码错误!");
                request.getRequestDispatcher("/index.jsp").forward(request, response);
                return;
            }
            pw.print("登录成功!");
        }
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

生成验证码

package qingxia.tang;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import cn.dsna.util.images.ValidateCode;


/**
 * Servlet implementation class ShowCode
 */
@WebServlet("/ShowCode")
public class ShowCode extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public ShowCode() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ValidateCode vc=new ValidateCode(110, 25, 4, 9);
        vc.write(response.getOutputStream());
        String code = vc.getCode();
        //将code写入session中
        request.getSession().setAttribute("ycode", code);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

效果图：

http://localhost:8080/session/index.jsp

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原文地址：https://www.cnblogs.com/xiaotang5051729/p/9834922.html