Cookie实现10天内免密登录

2020-08-18

原视频地址：https://www.bilibili.com/video/BV1vb41187jH?p=53

<!--login.html-->
<html>
    <head>
        <title>登录页面</title>
        <meta http-equiv = "keywords" content = "keyword1, keyword2, keyword3">
        <meta http-equiv = "description" content = "this is my page">
        <meta http-equiv = "content-type" content = "text/html;charset = UTF-8">
    </head>
    <body>
        <form action = "/webappname/login" method = "post">
            用户名
                <input type = "text" name = "username">
                <br>
            密码
                <input type = "password" name = "password">
                <br>
            <input type = "checkbox" name = "tenDayAutoLoginFlag" value = "ok">十天内免登录<br>
            
            <input type = "submit" value = "登录">
        </form>
    </body>
</html>

<!--login-error.html-->
<html>
    <head>
        <title>登录失败</title>
        <meta http-equiv = "keywords" content = "keyword1, keyword2, keyword3">
        <meta http-equiv = "description" content = "this is my page">
        <meta http-equiv = "content-type" content = "text/html;charset = UTF-8">
    </head>
    <body>
        <!--欢迎页面-->
        登录失败，用户名不存在或者密码错误，请<a href = "/webappname/login.html">重新登录</a>
    </body>
</html>

<!--web.xml-->
<welcome-file-list>
    <welcome-file>isLogin</welcome-file>
</welcome-file-list>

<servlet>
    <servlet-name>login</servlet-name>
    <!--Servlet全类名-->
    <servlet-class>包名.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>login</servlet-name>
    <!--请求路径-->
    <url-pattern>/login</url-pattern>
</servlet-mapping>

<servlet>
    <servlet-name>isLogin</servlet-name>
    <!--Servlet全类名-->
    <servlet-class>包名.CheckLoginStatusServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>isLogin</servlet-name>
    <!--请求路径-->
    <url-pattern>/isLogin</url-pattern>
</servlet-mapping>

// LoginServlet.java
public class LoginServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 获取用户名和密码
        request.setCharacterEncoding("UTF-8");
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        // JDBC连接数据验证用户名和密码
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        boolean loginSuccess = false;
        String realName = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "123");
            String sql = "select id,username,password realname from t_user where username=? and password=?";
            ps = conn.prepareStatement(sql);
            ps.setString(1, username);
            ps.setString(2, password);
            re = ps.executeQuery();
            if (rs.next()) {
                loginSuccess = true;
                realName = rs.getString("realname");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (rs != null) {
                try {
                    rs.close();
                } catch(SQLException e) {
                    e.printStackTrace();
                }
            }
            
            if (ps != null) {
                try {
                    ps.close();
                } catch(SQLException e) {
                    e.printStackTrace();
                }
            }
            
            if (conn != null) {
                try {
                    conn.close();
                } catch(SQLException e) {
                    e.printStackTrace();
                }
            }
        }
        
        
        if (loginSuccess) {
            // 登录成功之后，获取用户是否选择了十天内免登录
            String tenDayAutoLoginFlag = request.getParameter("tenDayAutoLoginFlag");
            if ("ok".equals(tenDayAutoLoginFlag)) {
                // 创建Cookie对象
                Cookie cookie1 = new Cookie("username", username);
                Cookie cookie2 = new Cookie("password", password);// password可以使用MD5加密
                // 设置有效时间
                cookie1.setMaxAge(60*60*24*10);
                cookie2.setMaxAge(60*60*24*10);
                // 设置关联路径
                cookie1.setPath(request.getContextPath()); 
                cookie2.setPath(request.getContextPath());
                // 发送Cookie给浏览器
                response.addCookie(cookie1);
                response.addCookie(cookie2);
            }
            // 登录成功跳转到成功页面
            response.setContentType("text/html;charset=UTF-8");
            PrintWriter out = response.getWriter();
            out.print("<html>");
            out.print("<head>");
            out.print("<title>欢迎页面</title>");
            out.print("</head>");
            out.print("<body>");
            out.print("欢迎");
            out.print(realName);
            out.print("访问");
            out.print("</body>");
            out.print("</html>");
        } else {
            // 登录失败跳转到失败页面
            response.sendRedirect(request.getContextPath + "/login-error.html");
        }
    }
}

// CheckLoginStatusServlet.java
public class CheckLoginStatusServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Cookie[] cookies = request.getCookies();
        String username = null;
        String password = null;
        if (cookies != null) {
            for (Cookie cookie : cookies) {
                String cookieName = cookie.getName();
                String cookieValue = cookie.getValue();
                if ("username".equals(cookieName)) {
                    username = cookieValue;
                } else if ("password".equals(cookieName)) {
                    password = cookieValue;
                }
            }
        }
        
        if (username != null && password != null) {
            // JDBC连接数据验证用户名和密码
            Connection conn = null;
            PreparedStatement ps = null;
            ResultSet rs = null;
            boolean loginSuccess = false;
            String realName = null;
            try {
                Class.forName("com.mysql.jdbc.Driver");
                conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "123");
                String sql = "select id,username,password realname from t_user where username=? and password=?";
                ps = conn.prepareStatement(sql);
                ps.setString(1, username);
                ps.setString(2, password);
                re = ps.executeQuery();
                if (rs.next()) {
                    loginSuccess = true;
                    realName = rs.getString("realname");
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (rs != null) {
                    try {
                        rs.close();
                    } catch(SQLException e) {
                        e.printStackTrace();
                    }
                }

                if (ps != null) {
                    try {
                        ps.close();
                    } catch(SQLException e) {
                        e.printStackTrace();
                    }
                }

                if (conn != null) {
                    try {
                        conn.close();
                    } catch(SQLException e) {
                        e.printStackTrace();
                    }
                }
            }
            if (loginSuccess) {
                // 登录成功跳转到成功页面
                response.setContentType("text/html;charset=UTF-8");
                PrintWriter out = response.getWriter();
                out.print("<html>");
                out.print("<head>");
                out.print("<title>欢迎页面</title>");
                out.print("</head>");
                out.print("<body>");
                out.print("欢迎");
                out.print(realName);
                out.print("访问");
                out.print("</body>");
                out.print("</html>");
            } else {
                // 登录失败跳转到失败页面
                response.sendRedirect(request.getContextPath + "/login-error.html");
            }
            
        } else {
            // 跳转到登录页面
            response.sendRedirect(request.getContextPath + "/login.html");
        }
    }
}

drop table if exists t_user;
create table t_user(
    id int(10) primary key auto_increment,
    username varchar(32) not null unique,
    password varchar(32) not null,
    realname varchar(128)
);

insert into t_user(username,password,realname) values ("admin","123","管理员");
insert into t_user(username,password,realname) values ("zhangsan","123","张三");
commit;
select * from t_user;