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验证码案例的代码实现和细节处理

作者:互联网

代码实现:

login.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>login</title>
    <script>
        window.onload = function () {
            document.getElementById("img").onclick = function () {
                this.src = "/checkCodeServlet1?time="+new Date().getTime();
            }
        }
    </script>
    <style>
        div{
            color: red;
        }
    </style>
</head>
<body>
    <form action="/loginServlet1" 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>
            </tr>
            <tr>
                <td colspan="2"><img id="img" src="/checkCodeServlet1"></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>
CheckCodeServlet:
@WebServlet("/checkCodeServlet1")
public class CheckCodeServlet1 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int width = 100;
        int height = 50;
        //1、创建一对象,在内存中画图(验证码图片对象)
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        //2、美化图片
        //填充背景色
        Graphics g = image.getGraphics();
        g.setColor(Color.PINK);
        g.fillRect(0,0,width,height);
        //画边框
        g.setColor(Color.BLUE);
        g.drawRect(0,0,width-1,height-1);
        //写验证码
        String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";
        //生成随机角标
        Random ra = new Random();

        StringBuilder sb = new StringBuilder();
        for (int i = 1; i <= 4; i++) {
            int index = ra.nextInt(str.length());
            //获取字符
            char c = str.charAt(index);
            sb.append(c);
            //写验证码
            g.drawString(c+"",width/5*i,height/2);
        }
        String checkCode_session = sb.toString();
        //将验证码存入session
        request.getSession().setAttribute("checkCode_session",checkCode_session);

        //画干扰线
        g.setColor(Color.GREEN);
        //随机生成坐标点
        for (int i = 0; i < 10; i++) {
            int x1 = ra.nextInt(width);
            int x2 = ra.nextInt(width);

            int y1 = ra.nextInt(height);
            int y2 = ra.nextInt(height);
            g.drawLine(x1,y1,x2,y2);
        }

        //3、将图片输出到页面展示
        ImageIO.write(image,"jpg",response.getOutputStream());
    }

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

LoginServlet:

@WebServlet("/loginServlet1")
public class LoginServlet1 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1、设置request编码
        request.setCharacterEncoding("utf-8");
        //2、获取参数
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String checkCode = request.getParameter("checkCode");
        //3、先获取生成的验证码
        HttpSession session = request.getSession();
        String checkCode_session = (String) session.getAttribute("checkCode_session");
        //判断验证码是否正确
        if (checkCode_session.equalsIgnoreCase(checkCode)){
            //忽略大小写比较
            //验证码正确
            //判断用户名和密码是否一致
            if ("zs".equals(username) && "123".equals(password)){//需要调用UserDao查询数据库
                //登录成功
                //存储信息,用户信息
                session.setAttribute("user",username);
                //重定向到success.jsp
                response.sendRedirect(request.getContextPath()+"/success.jsp");
            }else {
                //登录失败
                //存储提示信息到request
                request.setAttribute("login_error","用户名或密码错误");
                //转发到登录页面
                request.getRequestDispatcher("/login.jsp").forward(request,response);
            }
        }else {
            //验证码不一致
            //存储提示信息到request
            request.setAttribute("cc_error","验证码错误");
            //转发到登录页面
            request.getRequestDispatcher("/login.jsp").forward(request,response);
        }
    }

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

success.jsp:

<%@ 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>

 

 

 

 

细节处理

login.jsp

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

loginServlet:

@WebServlet("/loginServlet1")
public class LoginServlet1 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1、设置request编码
        request.setCharacterEncoding("utf-8");
        //2、获取参数
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String checkCode = request.getParameter("checkCode");
        //3、先获取生成的验证码
        HttpSession session = request.getSession();
        String checkCode_session = (String) session.getAttribute("checkCode_session");
        //删除session中存储的验证码
       session.removeAttribute("checkCode_session");
        //判断验证码是否正确
        if (checkCode_session != null && checkCode_session.equalsIgnoreCase(checkCode)){
            //忽略大小写比较
            //验证码正确
            //判断用户名和密码是否一致
            if ("zs".equals(username) && "123".equals(password)){//需要调用UserDao查询数据库
                //登录成功
                //存储信息,用户信息
                session.setAttribute("user",username);
                //重定向到success.jsp
                response.sendRedirect(request.getContextPath()+"/success.jsp");
            }else {
                //登录失败
                //存储提示信息到request
                request.setAttribute("login_error","用户名或密码错误");
                //转发到登录页面
                request.getRequestDispatcher("/login.jsp").forward(request,response);
            }
        }else {
            //验证码不一致
            //存储提示信息到request
            request.setAttribute("cc_error","验证码错误");
            //转发到登录页面
            request.getRequestDispatcher("/login.jsp").forward(request,response);
        }
    }

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

 

标签:String,checkCode,request,验证码,案例,细节,session,response
来源: https://www.cnblogs.com/xjw12345/p/16587358.html