Session+JSP Demo

时间 2019-11-08

标签 session+jsp session jsp demo 栏目网站开发繁體版

原文原文链接

验证码案例: 

需求:
 1.访问带有验证码的登陆页面login.js
 2.用户输入用户名和密码

若是用户名和密码错误,跳转到登陆页面,提示用户名密码错误
若是验证码有误,跳转到登陆页面,提示验证码错误
若是所有输入正确,则跳转到success.jsp,显示用户名,欢迎您!


步骤:
 1.设置request的编码
 2.获取参数Map集合
 3.获取验证码
 4.将用户信息封装到User对象
 5.判断程序生成的验证码和用户输入的验证码是否一致,从session中获取程序生成的验证码
      *一致
          在此判断用户名和密码是否一致(查询数据库)
             正确:登陆成功,存储数据,跳转到页面(重定向Session域)
             不正确:给提示信息,跳转登陆页面

     *不一致
          1.给用户提示信息,验证码错误 request
          2.跳转登陆页面 转发

LoginServlet

package com.infosys.session; 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 javax.servlet.http.HttpSession; import java.io.IOException; @WebServlet("/LoginServlet") public class LoginServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); String username = request.getParameter("username"); String password = request.getParameter("password"); String checkCode = request.getParameter("checkCode"); HttpSession session = request.getSession(); String checkCode_session = (String) session.getAttribute("checkCode_session"); if (checkCode_session.equalsIgnoreCase(checkCode)) { if ("zhangsan".equals(username) && "123".equals(password)) { session.setAttribute("user", username); response.sendRedirect(request.getContextPath() + "/success.jsp"); } else { request.setAttribute("login_error", "用户名或密码错误"); request.getRequestDispatcher("/login.jsp").forward(request, response); } } else { request.setAttribute("cc_error", "验证码错误"); request.getRequestDispatcher("/login.jsp").forward(request, response); } } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } }

CheckCodeServlet

package com.infosys.servlet; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.awt.*; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.Random; @WebServlet("/checkCodeServlet") public class CheckCodeServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { int width = 100; int height = 50; //1.建立一对象，在内存中图片(验证码图片对象)
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); //2.美化图片 //2.1 填充背景色
        Graphics g = image.getGraphics();//画笔对象
        g.setColor(Color.PINK);//设置画笔颜色
        g.fillRect(0, 0, width, height); //2.2画边框
 g.setColor(Color.BLUE); g.drawRect(0, 0, width - 1, height - 1); String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789"; //生成随机角标
        Random ran = new Random(); StringBuilder sb = new StringBuilder(); for (int i = 1; i <= 4; i++) { int index = ran.nextInt(str.length()); //获取字符
            char ch = str.charAt(index);//随机字符
 sb.append(ch); //2.3写验证码
            g.drawString(ch + "", width / 5 * i, height / 2); } String checkCode_session = sb.toString(); request.getSession().setAttribute("checkCode_session", checkCode_session); //2.4画干扰线
 g.setColor(Color.GREEN); //随机生成坐标点

        for (int i = 0; i < 10; i++) { int x1 = ran.nextInt(width); int x2 = ran.nextInt(width); int y1 = ran.nextInt(height); int y2 = ran.nextInt(height); g.drawLine(x1, y1, x2, y2); } //3.将图片输出到页面展现
        ImageIO.write(image, "jpg", response.getOutputStream()); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } }

login.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
    <script> window.onload = function () { document.getElementById("img").onclick = function () { this.src = "/cookie/checkCodeServlet?time=" + new Date().getTime(); } } </script>
</head>

<body>
<form action="/cookie/LoginServlet" method="post">
    <table>
        <tr>
            <td>用户名</td>
            <td><input type="text" name="username"/></td>
        </tr>
        <tr>
            <td>密码</td>
            <td><input type="password" name="password"/></td>
        </tr>
        <tr>
            <td>验证码</td>
            <td><input type="text" name="checkCode"/></td>

            <td colspan="2"><img src="/cookie/checkCodeServlet" id="img"/></td>
        </tr>
        <tr>
            <td colspan="2"><input type="submit" value="登陆"/></td>
        </tr>
    </table>
</form>


<div><%= request.getAttribute("cc_error")%>
</div>
<div><%= request.getAttribute("login_error")%>
</div>

</body>
</html>

success.jsphtml

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h1><%=request.getSession().getAttribute("user")%>,欢迎您</h1>
</body>
</html>

真实数据查询数据库java