JAVA-EE部门OA管理系统后端Servlet部分------计算机网络经典

￡神魔★判官ぃ 2024-02-20 09:15 17阅读 0赞

>     package com.bjpowernode.oa.action;
>     
>     import com.bjpowernode.oa.utils.DBUtil;
>     import com.bjpowernode.oa.Pojo.Dept;
>     import jakarta.servlet.ServletException;
>     import jakarta.servlet.annotation.WebServlet;
>     import jakarta.servlet.http.HttpServlet;
>     import jakarta.servlet.http.HttpServletRequest;
>     import jakarta.servlet.http.HttpServletResponse;
>     
>     import java.io.IOException;
>     import java.sql.Connection;
>     import java.sql.PreparedStatement;
>     import java.sql.ResultSet;
>     import java.sql.SQLException;
>     import java.util.ArrayList;
>     import java.util.List;
>     
>     @WebServlet(urlPatterns = {"/dept/list","/dept/detail","/dept/delete","/dept/save","/dept/edit"})
>     public class DeptServlet extends HttpServlet
>     {
>         @Override
>         protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             String servletPath = request.getServletPath();
>             if("/dept/list".equals(servletPath))
>             {
>                 doList(request,response);
>             }
>             else if("/dept/detail".equals(servletPath))
>             {
>                 doDetail(request,response);
>             }
>             else if("/dept/delete".equals(servletPath))
>             {
>                 doDel(request,response);
>             }
>             else if("/dept/save".equals(servletPath))
>             {
>                 doSave(request,response);
>             }
>             else if("/dept/edit".equals(servletPath))
>             {
>                 doModify(request,response);
>             }
>         }
>     
>         private void doModify(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             Integer deptno = Integer.parseInt(request.getParameter("deptno"));
>             String dname = request.getParameter("dname");
>             String loc = request.getParameter("loc");
>             Connection connection = null;
>             PreparedStatement statement = null;
>             ResultSet resultSet = null;
>             int count = 0;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 connection.setAutoCommit(false);
>                 String sql = "update dept set dname = ?,loc = ? where deptno = ?";
>                 statement = connection.prepareStatement(sql);
>                 statement.setString(1,dname);
>                 statement.setString(2,loc);
>                 statement.setInt(3,deptno);
>                 count = statement.executeUpdate();
>                 connection.commit();
>             }
>             catch (SQLException e)
>             {
>                 if (connection != null)
>                 {
>                     try
>                     {
>                         connection.rollback();
>                     }
>                     catch (SQLException ex)
>                     {
>                         throw new RuntimeException(ex);
>                     }
>                 }
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(connection,statement,resultSet);
>             }
>             if(count == 1)
>             {
>                 response.sendRedirect(request.getContextPath() +  "/dept/list");
>             }
>             else
>             {
>                 response.sendRedirect(request.getContextPath() + "/Error.jsp");
>             }
>         }
>     
>         private void doSave(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             Integer deptno = Integer.parseInt(request.getParameter("deptno"));
>             String dname = request.getParameter("dname");
>             String loc = request.getParameter("loc");
>             Connection connection = null;
>             PreparedStatement statement = null;
>             ResultSet resultSet = null;
>             int count = 0;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 connection.setAutoCommit(false);
>                 String sql = "insert into dept(deptno,dname,loc) values(?,?,?)";
>                 statement = connection.prepareStatement(sql);
>                 statement.setInt(1,deptno);
>                 statement.setString(2,dname);
>                 statement.setString(3,loc);
>                 count = statement.executeUpdate();
>                 connection.commit();
>     
>             }
>             catch (SQLException e)
>             {
>                 if (connection != null)
>                 {
>                     try
>                     {
>                         connection.rollback();
>                     }
>                     catch (SQLException ex)
>                     {
>                         throw new RuntimeException(ex);
>                     }
>                 }
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(connection,statement,resultSet);
>             }
>             if(count == 1)
>             {
>                 response.sendRedirect(request.getContextPath() +  "/dept/list");
>             }
>             else
>             {
>                 response.sendRedirect(request.getContextPath() + "/Error.jsp");
>             }
>         }
>     
>         private void doDel(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             Connection connection = null;
>             PreparedStatement statement = null;
>             ResultSet resultSet = null;
>             String deptno = request.getParameter("deptno");
>             int count = 0;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 connection.setAutoCommit(false);
>                 String sql = "delete from dept where deptno = ?";
>                 statement = connection.prepareStatement(sql);
>                 statement.setString(1,deptno);
>                 count = statement.executeUpdate();
>                 connection.commit();
>             }
>             catch (SQLException e)
>             {
>                 if (connection != null)
>                 {
>                     try
>                     {
>                         connection.rollback();
>                     }
>                     catch (SQLException ex)
>                     {
>                         throw new RuntimeException(ex);
>                     }
>                 }
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(connection,statement,resultSet);
>             }
>             if(count == 1)
>             {
>                 response.sendRedirect(request.getContextPath() + "/dept/list");
>             }
>             else
>             {
>                 response.sendRedirect(request.getContextPath() + "/Error.jsp");
>             }
>         }
>     
>         private void doDetail(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             Connection connection = null;
>             PreparedStatement statement = null;
>             ResultSet resultSet = null;
>             String deptno = request.getParameter("deptno");
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "select * from dept where deptno = ?";
>                 statement = connection.prepareStatement(sql);
>                 statement.setString(1,deptno);
>                 resultSet = statement.executeQuery();
>                 if(resultSet.next())
>                 {
>                     String dname = resultSet.getString("dname");
>                     String loc = resultSet.getString("loc");
>                     Dept dept = new Dept(deptno,dname,loc);
>                     request.setAttribute("dept",dept);
>                 }
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(connection,statement,resultSet);
>             }
>             String flag = request.getParameter("f");
>             if("d".equals(flag))
>             {
>                 request.getRequestDispatcher("/detail.jsp").forward(request,response);
>             }
>             if("m".equals(flag))
>             {
>                 request.getRequestDispatcher("/edit.jsp").forward(request,response);
>             }
>         }
>     
>         private void doList(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             //连接数据库,查询所有部门信息
>             Connection connection = null;
>             PreparedStatement statement = null;
>             ResultSet resultSet = null;
>             List<Dept> list = new ArrayList<Dept>();
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "select * from dept";
>                 statement = connection.prepareStatement(sql);
>                 resultSet = statement.executeQuery();
>                 while(resultSet.next())
>                 {
>                     String deptno = resultSet.getString("deptno");
>                     String dname = resultSet.getString("dname");
>                     String loc = resultSet.getString("loc");
>                     Dept dept = new Dept(deptno,dname,loc);
>                     list.add(dept);
>                 }
>                 request.setAttribute("depts",list);
>                 request.getRequestDispatcher("/list.jsp").forward(request,response);
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(connection,statement,resultSet);
>             }
>         }
>     }
> 
>     package com.bjpowernode.oa.action;
>     
>     import com.bjpowernode.oa.utils.DBUtil;
>     import com.bjpowernode.oa.Pojo.Dept;
>     import jakarta.servlet.ServletException;
>     import jakarta.servlet.annotation.WebServlet;
>     import jakarta.servlet.http.HttpServlet;
>     import jakarta.servlet.http.HttpServletRequest;
>     import jakarta.servlet.http.HttpServletResponse;
>     
>     import java.io.IOException;
>     import java.sql.Connection;
>     import java.sql.PreparedStatement;
>     import java.sql.ResultSet;
>     import java.sql.SQLException;
>     import java.util.ArrayList;
>     import java.util.List;
>     
>     @WebServlet(urlPatterns = {"/dept/list","/dept/detail","/dept/delete","/dept/save","/dept/edit"})
>     public class DeptServlet extends HttpServlet
>     {
>         @Override
>         protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             String servletPath = request.getServletPath();
>             if("/dept/list".equals(servletPath))
>             {
>                 doList(request,response);
>             }
>             else if("/dept/detail".equals(servletPath))
>             {
>                 doDetail(request,response);
>             }
>             else if("/dept/delete".equals(servletPath))
>             {
>                 doDel(request,response);
>             }
>             else if("/dept/save".equals(servletPath))
>             {
>                 doSave(request,response);
>             }
>             else if("/dept/edit".equals(servletPath))
>             {
>                 doModify(request,response);
>             }
>         }
>     
>         private void doModify(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             Integer deptno = Integer.parseInt(request.getParameter("deptno"));
>             String dname = request.getParameter("dname");
>             String loc = request.getParameter("loc");
>             Connection connection = null;
>             PreparedStatement statement = null;
>             ResultSet resultSet = null;
>             int count = 0;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 connection.setAutoCommit(false);
>                 String sql = "update dept set dname = ?,loc = ? where deptno = ?";
>                 statement = connection.prepareStatement(sql);
>                 statement.setString(1,dname);
>                 statement.setString(2,loc);
>                 statement.setInt(3,deptno);
>                 count = statement.executeUpdate();
>                 connection.commit();
>             }
>             catch (SQLException e)
>             {
>                 if (connection != null)
>                 {
>                     try
>                     {
>                         connection.rollback();
>                     }
>                     catch (SQLException ex)
>                     {
>                         throw new RuntimeException(ex);
>                     }
>                 }
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(connection,statement,resultSet);
>             }
>             if(count == 1)
>             {
>                 response.sendRedirect(request.getContextPath() +  "/dept/list");
>             }
>             else
>             {
>                 response.sendRedirect(request.getContextPath() + "/Error.jsp");
>             }
>         }
>     
>         private void doSave(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             Integer deptno = Integer.parseInt(request.getParameter("deptno"));
>             String dname = request.getParameter("dname");
>             String loc = request.getParameter("loc");
>             Connection connection = null;
>             PreparedStatement statement = null;
>             ResultSet resultSet = null;
>             int count = 0;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 connection.setAutoCommit(false);
>                 String sql = "insert into dept(deptno,dname,loc) values(?,?,?)";
>                 statement = connection.prepareStatement(sql);
>                 statement.setInt(1,deptno);
>                 statement.setString(2,dname);
>                 statement.setString(3,loc);
>                 count = statement.executeUpdate();
>                 connection.commit();
>     
>             }
>             catch (SQLException e)
>             {
>                 if (connection != null)
>                 {
>                     try
>                     {
>                         connection.rollback();
>                     }
>                     catch (SQLException ex)
>                     {
>                         throw new RuntimeException(ex);
>                     }
>                 }
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(connection,statement,resultSet);
>             }
>             if(count == 1)
>             {
>                 response.sendRedirect(request.getContextPath() +  "/dept/list");
>             }
>             else
>             {
>                 response.sendRedirect(request.getContextPath() + "/Error.jsp");
>             }
>         }
>     
>         private void doDel(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             Connection connection = null;
>             PreparedStatement statement = null;
>             ResultSet resultSet = null;
>             String deptno = request.getParameter("deptno");
>             int count = 0;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 connection.setAutoCommit(false);
>                 String sql = "delete from dept where deptno = ?";
>                 statement = connection.prepareStatement(sql);
>                 statement.setString(1,deptno);
>                 count = statement.executeUpdate();
>                 connection.commit();
>             }
>             catch (SQLException e)
>             {
>                 if (connection != null)
>                 {
>                     try
>                     {
>                         connection.rollback();
>                     }
>                     catch (SQLException ex)
>                     {
>                         throw new RuntimeException(ex);
>                     }
>                 }
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(connection,statement,resultSet);
>             }
>             if(count == 1)
>             {
>                 response.sendRedirect(request.getContextPath() + "/dept/list");
>             }
>             else
>             {
>                 response.sendRedirect(request.getContextPath() + "/Error.jsp");
>             }
>         }
>     
>         private void doDetail(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             Connection connection = null;
>             PreparedStatement statement = null;
>             ResultSet resultSet = null;
>             String deptno = request.getParameter("deptno");
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "select * from dept where deptno = ?";
>                 statement = connection.prepareStatement(sql);
>                 statement.setString(1,deptno);
>                 resultSet = statement.executeQuery();
>                 if(resultSet.next())
>                 {
>                     String dname = resultSet.getString("dname");
>                     String loc = resultSet.getString("loc");
>                     Dept dept = new Dept(deptno,dname,loc);
>                     request.setAttribute("dept",dept);
>                 }
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(connection,statement,resultSet);
>             }
>             String flag = request.getParameter("f");
>             if("d".equals(flag))
>             {
>                 request.getRequestDispatcher("/detail.jsp").forward(request,response);
>             }
>             if("m".equals(flag))
>             {
>                 request.getRequestDispatcher("/edit.jsp").forward(request,response);
>             }
>         }
>     
>         private void doList(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             //连接数据库,查询所有部门信息
>             Connection connection = null;
>             PreparedStatement statement = null;
>             ResultSet resultSet = null;
>             List<Dept> list = new ArrayList<Dept>();
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "select * from dept";
>                 statement = connection.prepareStatement(sql);
>                 resultSet = statement.executeQuery();
>                 while(resultSet.next())
>                 {
>                     String deptno = resultSet.getString("deptno");
>                     String dname = resultSet.getString("dname");
>                     String loc = resultSet.getString("loc");
>                     Dept dept = new Dept(deptno,dname,loc);
>                     list.add(dept);
>                 }
>                 request.setAttribute("depts",list);
>                 request.getRequestDispatcher("/list.jsp").forward(request,response);
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(connection,statement,resultSet);
>             }
>         }
>     }

>     package com.bjpowernode.oa.action;
>     
>     import com.bjpowernode.oa.Pojo.User;
>     import com.bjpowernode.oa.utils.DBUtil;
>     import jakarta.servlet.ServletException;
>     import jakarta.servlet.annotation.WebServlet;
>     import jakarta.servlet.http.*;
>     
>     import java.io.IOException;
>     import java.sql.Connection;
>     import java.sql.PreparedStatement;
>     import java.sql.ResultSet;
>     import java.sql.SQLException;
>     
>     @WebServlet({"/user/login","/user/exit"})
>     public class UserServlet extends HttpServlet
>     {
>         //JSessionID=??这个键值对数据就是cookie保存的信息
>         //对于session关联的cookie来说,这个cookie是保存在浏览器的运行内存中的
>         //用户再次发送请求的时候,会自动把运行内存中的cookie放到请求头内一并发送
>         //服务器就是根据这个值找到对应的对象
>         //session存储在服务器上的,cookie是储存在电脑机器上的
>         //cookie可以存在浏览器运行内存中,也可以放在硬盘内保存
>         //cookie和session都是为了保存会话的状态
>         //这两个机制存在的目的就是为了解决我们的http协议的无状态无连接协议的问题
>         //(无状态无连接)没有请求和响应时,双方不知道对方是否还在
>         @Override
>         public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             String servletPath = request.getServletPath();
>             request.setCharacterEncoding("UTF-8");
>             response.setContentType("text/html;charset=UTF-8");
>             if("/user/login".equals(servletPath))
>             {
>                 doLogin(request,response);
>             }
>             else if("/user/exit".equals(servletPath))
>             {
>                 doExit(request,response);
>             }
>         }
>         //将购物车中的商品编号放到cookie当中,cookie保存到硬盘
>         //下一次再打开,自动读取本地cookie,就还会显示这些商品
>         //购物网站未登录不允许查看商品和保存购物车的原理是,为了记录数据,什么用户喜欢什么样的东西
>         //和针对不同用户给出不同的优惠力度(大数据杀熟),并且可以防止爬虫,和减轻服务器压力(没有购买欲望的客户不让你看)
>         //十天免登录的实现原理如下,保存一个记录了用户名和密码的cookie到本地
>         //当十天内再次访问该网站时,会自动在请求头内发送这个账号用户名和密码到服务器,服务器接收到这个cookie
>         //解密后实现登录
>         //cookie和session都是Http协议的一部分,因为Http协议是无状态和无连接的协议
>         //Http协议规定,任何一个cookie都是由name和value组成的
>         //在java的servlet中,对cookie提供了那些支持?
>         //jakarta.servlet.http.HttpCookie
>         //Cookie是带有路径的,不同的cookie会带不同的路径,方便对应的提交信息和用于握手机制的实现
>         //我们java的cookie主要是在response中将信息作为回传给浏览器的,在服务器中只是做一个信息的处理
>         //在Http协议中规定如下,在浏览器发送请求时,会自动携带该路径下的cookie在请求头中给服务器
>         //cookie的name和value都是字符串,cookie的name和value都是字符串
>         private void doExit(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             HttpSession session = request.getSession(false);
>             if(session != null && session.getAttribute("user") != null)
>             {
>                 //从session域中移除对象
>                 session.removeAttribute("user");
>                 //销毁session的方法,session.invalidate()
>                 session.invalidate();
>                 Cookie[] cookies = request.getCookies();
>                 for (Cookie cookie : cookies)
>                 {
>                     cookie.setMaxAge(0);
>                     cookie.setPath(request.getContextPath());
>                     response.addCookie(cookie);
>                 }
>                 response.sendRedirect(request.getContextPath());
>             }
>         }
>         protected void doLogin(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             String username = request.getParameter("username");
>             String password = request.getParameter("password");
>             String loginSet = request.getParameter("flag");
>             Connection connection = null;
>             PreparedStatement statement = null;
>             ResultSet resultSet = null;
>             boolean flag = false;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "select * from t_user where username = ? and pssword = ?";
>                 statement = connection.prepareStatement(sql);
>                 statement.setString(1,username);
>                 statement.setString(2,password);
>                 resultSet = statement.executeQuery();
>                 if(resultSet.next())
>                 {
>                     flag = true;
>                 }
>     
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(connection,statement,resultSet);
>             }
>             if(flag)
>             {
>                 HttpSession session = request.getSession();
>                 session.setAttribute("user",new User(username,password));
>                 if(loginSet != null && "1".equals(loginSet))
>                 {
>                     //存储登录名
>                     Cookie name = new Cookie("username",username);
>                     //存储密码
>                     Cookie LoginPassword = new Cookie("password",password);
>                     //生命周期都设为1小时,实验够了
>                     name.setMaxAge(60 * 60);
>                     LoginPassword.setMaxAge(60 * 60);
>                     //保存到浏览器中
>                     name.setPath(request.getContextPath());
>                     LoginPassword.setPath(request.getContextPath());
>                     //添加到响应中去
>                     response.addCookie(name);
>                     response.addCookie(LoginPassword);
>                 }
>                 response.sendRedirect(request.getContextPath() + "/dept/list");
>             }
>             else
>             {
>                 response.sendRedirect(request.getContextPath() + "/Error.jsp");
>             }
>         }
>     }
> 
>     package com.bjpowernode.oa.action;
>     
>     import com.bjpowernode.oa.Pojo.User;
>     import com.bjpowernode.oa.utils.DBUtil;
>     import jakarta.servlet.ServletException;
>     import jakarta.servlet.annotation.WebServlet;
>     import jakarta.servlet.http.*;
>     
>     import java.io.IOException;
>     import java.sql.Connection;
>     import java.sql.PreparedStatement;
>     import java.sql.ResultSet;
>     import java.sql.SQLException;
>     
>     @WebServlet({"/user/login","/user/exit"})
>     public class UserServlet extends HttpServlet
>     {
>         //JSessionID=??这个键值对数据就是cookie保存的信息
>         //对于session关联的cookie来说,这个cookie是保存在浏览器的运行内存中的
>         //用户再次发送请求的时候,会自动把运行内存中的cookie放到请求头内一并发送
>         //服务器就是根据这个值找到对应的对象
>         //session存储在服务器上的,cookie是储存在电脑机器上的
>         //cookie可以存在浏览器运行内存中,也可以放在硬盘内保存
>         //cookie和session都是为了保存会话的状态
>         //这两个机制存在的目的就是为了解决我们的http协议的无状态无连接协议的问题
>         //(无状态无连接)没有请求和响应时,双方不知道对方是否还在
>         @Override
>         public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             String servletPath = request.getServletPath();
>             request.setCharacterEncoding("UTF-8");
>             response.setContentType("text/html;charset=UTF-8");
>             if("/user/login".equals(servletPath))
>             {
>                 doLogin(request,response);
>             }
>             else if("/user/exit".equals(servletPath))
>             {
>                 doExit(request,response);
>             }
>         }
>         //将购物车中的商品编号放到cookie当中,cookie保存到硬盘
>         //下一次再打开,自动读取本地cookie,就还会显示这些商品
>         //购物网站未登录不允许查看商品和保存购物车的原理是,为了记录数据,什么用户喜欢什么样的东西
>         //和针对不同用户给出不同的优惠力度(大数据杀熟),并且可以防止爬虫,和减轻服务器压力(没有购买欲望的客户不让你看)
>         //十天免登录的实现原理如下,保存一个记录了用户名和密码的cookie到本地
>         //当十天内再次访问该网站时,会自动在请求头内发送这个账号用户名和密码到服务器,服务器接收到这个cookie
>         //解密后实现登录
>         //cookie和session都是Http协议的一部分,因为Http协议是无状态和无连接的协议
>         //Http协议规定,任何一个cookie都是由name和value组成的
>         //在java的servlet中,对cookie提供了那些支持?
>         //jakarta.servlet.http.HttpCookie
>         //Cookie是带有路径的,不同的cookie会带不同的路径,方便对应的提交信息和用于握手机制的实现
>         //我们java的cookie主要是在response中将信息作为回传给浏览器的,在服务器中只是做一个信息的处理
>         //在Http协议中规定如下,在浏览器发送请求时,会自动携带该路径下的cookie在请求头中给服务器
>         //cookie的name和value都是字符串,cookie的name和value都是字符串
>         private void doExit(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             HttpSession session = request.getSession(false);
>             if(session != null && session.getAttribute("user") != null)
>             {
>                 //从session域中移除对象
>                 session.removeAttribute("user");
>                 //销毁session的方法,session.invalidate()
>                 session.invalidate();
>                 Cookie[] cookies = request.getCookies();
>                 for (Cookie cookie : cookies)
>                 {
>                     cookie.setMaxAge(0);
>                     cookie.setPath(request.getContextPath());
>                     response.addCookie(cookie);
>                 }
>                 response.sendRedirect(request.getContextPath());
>             }
>         }
>         protected void doLogin(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             String username = request.getParameter("username");
>             String password = request.getParameter("password");
>             String loginSet = request.getParameter("flag");
>             Connection connection = null;
>             PreparedStatement statement = null;
>             ResultSet resultSet = null;
>             boolean flag = false;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "select * from t_user where username = ? and pssword = ?";
>                 statement = connection.prepareStatement(sql);
>                 statement.setString(1,username);
>                 statement.setString(2,password);
>                 resultSet = statement.executeQuery();
>                 if(resultSet.next())
>                 {
>                     flag = true;
>                 }
>     
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(connection,statement,resultSet);
>             }
>             if(flag)
>             {
>                 HttpSession session = request.getSession();
>                 session.setAttribute("user",new User(username,password));
>                 if(loginSet != null && "1".equals(loginSet))
>                 {
>                     //存储登录名
>                     Cookie name = new Cookie("username",username);
>                     //存储密码
>                     Cookie LoginPassword = new Cookie("password",password);
>                     //生命周期都设为1小时,实验够了
>                     name.setMaxAge(60 * 60);
>                     LoginPassword.setMaxAge(60 * 60);
>                     //保存到浏览器中
>                     name.setPath(request.getContextPath());
>                     LoginPassword.setPath(request.getContextPath());
>                     //添加到响应中去
>                     response.addCookie(name);
>                     response.addCookie(LoginPassword);
>                 }
>                 response.sendRedirect(request.getContextPath() + "/dept/list");
>             }
>             else
>             {
>                 response.sendRedirect(request.getContextPath() + "/Error.jsp");
>             }
>         }
>     }

>     package com.bjpowernode.oa.filter;
>     
>     import jakarta.servlet.*;
>     import jakarta.servlet.http.HttpServletRequest;
>     import jakarta.servlet.http.HttpServletResponse;
>     import jakarta.servlet.http.HttpSession;
>     
>     import java.io.IOException;
>     
>     public class LoginFilter implements Filter {
>         @Override
>         public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException
>         {
>             HttpServletRequest request = (HttpServletRequest)req;
>             HttpServletResponse response = (HttpServletResponse)res;
>             request.setCharacterEncoding("UTF-8");
>             response.setContentType("text/html;charset=UTF-8");
>             HttpSession session = request.getSession(false);
>             if(session != null && session.getAttribute("user") != null)
>             {
>                 chain.doFilter(request,response);
>             }
>             else
>             {
>                 response.sendRedirect(request.getContextPath() + "/index.jsp");
>             }
>         }
>     }
> 
>     package com.bjpowernode.oa.filter;
>     
>     import jakarta.servlet.*;
>     import jakarta.servlet.http.HttpServletRequest;
>     import jakarta.servlet.http.HttpServletResponse;
>     import jakarta.servlet.http.HttpSession;
>     
>     import java.io.IOException;
>     
>     public class LoginFilter implements Filter {
>         @Override
>         public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException
>         {
>             HttpServletRequest request = (HttpServletRequest)req;
>             HttpServletResponse response = (HttpServletResponse)res;
>             request.setCharacterEncoding("UTF-8");
>             response.setContentType("text/html;charset=UTF-8");
>             HttpSession session = request.getSession(false);
>             if(session != null && session.getAttribute("user") != null)
>             {
>                 chain.doFilter(request,response);
>             }
>             else
>             {
>                 response.sendRedirect(request.getContextPath() + "/index.jsp");
>             }
>         }
>     }

>     package com.bjpowernode.oa.Pojo;
>     
>     import java.util.Objects;
>     
>     public class Dept
>     {
>         private String deptno;
>         private String dname;
>         private String loc;
>     
>         @Override
>         public String toString() {
>             return "Dept{" +
>                     "deptno='" + deptno + '\'' +
>                     ", dname='" + dname + '\'' +
>                     ", loc='" + loc + '\'' +
>                     '}';
>         }
>     
>         @Override
>         public boolean equals(Object o) {
>             if (this == o) return true;
>             if (o == null || getClass() != o.getClass()) return false;
>             Dept dept = (Dept) o;
>             return Objects.equals(deptno, dept.deptno) && Objects.equals(dname, dept.dname) && Objects.equals(loc, dept.loc);
>         }
>     
>         @Override
>         public int hashCode() {
>             return Objects.hash(deptno, dname, loc);
>         }
>     
>         public String getDeptno() {
>             return deptno;
>         }
>     
>         public void setDeptno(String deptno) {
>             this.deptno = deptno;
>         }
>     
>         public String getDname() {
>             return dname;
>         }
>     
>         public void setDname(String dname) {
>             this.dname = dname;
>         }
>     
>         public String getLoc() {
>             return loc;
>         }
>     
>         public void setLoc(String loc) {
>             this.loc = loc;
>         }
>     
>         public Dept() {
>         }
>     
>         public Dept(String deptno, String dname, String loc) {
>             this.deptno = deptno;
>             this.dname = dname;
>             this.loc = loc;
>         }
>     }
> 
>     package com.bjpowernode.oa.Pojo;
>     
>     import java.util.Objects;
>     
>     public class Dept
>     {
>         private String deptno;
>         private String dname;
>         private String loc;
>     
>         @Override
>         public String toString() {
>             return "Dept{" +
>                     "deptno='" + deptno + '\'' +
>                     ", dname='" + dname + '\'' +
>                     ", loc='" + loc + '\'' +
>                     '}';
>         }
>     
>         @Override
>         public boolean equals(Object o) {
>             if (this == o) return true;
>             if (o == null || getClass() != o.getClass()) return false;
>             Dept dept = (Dept) o;
>             return Objects.equals(deptno, dept.deptno) && Objects.equals(dname, dept.dname) && Objects.equals(loc, dept.loc);
>         }
>     
>         @Override
>         public int hashCode() {
>             return Objects.hash(deptno, dname, loc);
>         }
>     
>         public String getDeptno() {
>             return deptno;
>         }
>     
>         public void setDeptno(String deptno) {
>             this.deptno = deptno;
>         }
>     
>         public String getDname() {
>             return dname;
>         }
>     
>         public void setDname(String dname) {
>             this.dname = dname;
>         }
>     
>         public String getLoc() {
>             return loc;
>         }
>     
>         public void setLoc(String loc) {
>             this.loc = loc;
>         }
>     
>         public Dept() {
>         }
>     
>         public Dept(String deptno, String dname, String loc) {
>             this.deptno = deptno;
>             this.dname = dname;
>             this.loc = loc;
>         }
>     }

>     package com.bjpowernode.oa.Pojo;
>     
>     import jakarta.servlet.ServletContext;
>     import jakarta.servlet.http.HttpSessionBindingEvent;
>     import jakarta.servlet.http.HttpSessionBindingListener;
>     
>     public class User implements HttpSessionBindingListener
>     {
>         private String username;
>         private String password;
>     
>         public User() {
>         }
>     
>         @Override
>         public String toString() {
>             return "User{" +
>                     "username='" + username + '\'' +
>                     ", password='" + password + '\'' +
>                     '}';
>         }
>     
>         @Override
>         public void valueBound(HttpSessionBindingEvent event) {
>             ServletContext application = event.getSession().getServletContext();
>             Long onlineCount = (Long)application.getAttribute("onlineCount");
>             if(onlineCount == null)
>             {
>                 application.setAttribute("onlineCount",1L);
>             }
>             else
>             {
>                 onlineCount++;
>                 application.setAttribute("onlineCount",onlineCount);
>             }
>         }
>     
>         @Override
>         public void valueUnbound(HttpSessionBindingEvent event) {
>             //因为是推出登录,所以必定不会是null空值
>             ServletContext application = event.getSession().getServletContext();
>             Long onlineCount = (Long)application.getAttribute("onlineCount");
>             onlineCount--;
>             application.setAttribute("onlineCount",onlineCount);
>         }
>     
>         public String getUsername() {
>             return username;
>         }
>     
>         public void setUsername(String username) {
>             this.username = username;
>         }
>     
>         public String getPassword() {
>             return password;
>         }
>     
>         public void setPassword(String password) {
>             this.password = password;
>         }
>     
>         public User(String username, String password) {
>             this.username = username;
>             this.password = password;
>         }
>     }
> 
>     package com.bjpowernode.oa.Pojo;
>     
>     import jakarta.servlet.ServletContext;
>     import jakarta.servlet.http.HttpSessionBindingEvent;
>     import jakarta.servlet.http.HttpSessionBindingListener;
>     
>     public class User implements HttpSessionBindingListener
>     {
>         private String username;
>         private String password;
>     
>         public User() {
>         }
>     
>         @Override
>         public String toString() {
>             return "User{" +
>                     "username='" + username + '\'' +
>                     ", password='" + password + '\'' +
>                     '}';
>         }
>     
>         @Override
>         public void valueBound(HttpSessionBindingEvent event) {
>             ServletContext application = event.getSession().getServletContext();
>             Long onlineCount = (Long)application.getAttribute("onlineCount");
>             if(onlineCount == null)
>             {
>                 application.setAttribute("onlineCount",1L);
>             }
>             else
>             {
>                 onlineCount++;
>                 application.setAttribute("onlineCount",onlineCount);
>             }
>         }
>     
>         @Override
>         public void valueUnbound(HttpSessionBindingEvent event) {
>             //因为是推出登录,所以必定不会是null空值
>             ServletContext application = event.getSession().getServletContext();
>             Long onlineCount = (Long)application.getAttribute("onlineCount");
>             onlineCount--;
>             application.setAttribute("onlineCount",onlineCount);
>         }
>     
>         public String getUsername() {
>             return username;
>         }
>     
>         public void setUsername(String username) {
>             this.username = username;
>         }
>     
>         public String getPassword() {
>             return password;
>         }
>     
>         public void setPassword(String password) {
>             this.password = password;
>         }
>     
>         public User(String username, String password) {
>             this.username = username;
>             this.password = password;
>         }
>     }

>     package com.bjpowernode.oa.utils;
>     
>     import java.sql.*;
>     import java.util.ResourceBundle;
>     
>     public class DBUtil
>     {
>         private static ResourceBundle bundle = ResourceBundle.getBundle("resources.jdbc");
>         private static String driver = bundle.getString("driver");
>         private static String url = bundle.getString("url");
>         private static String user = bundle.getString("user");
>         private static String password = bundle.getString("password");
>         //JDBC工具类
>         static
>         {
>             //注册驱动
>             try
>             {
>     //            Class.forName("com.mysql.jdbc.Driver");//避免写死
>                 Class.forName(driver);
>             }
>             catch (ClassNotFoundException e)
>             {
>                 throw new RuntimeException(e);
>             }
>         }
>         public static Connection getConnection() throws SQLException {
>             //获取链接
>             return DriverManager.getConnection(url,user,password);
>         }
>         //释放资源
>         public static void close(Connection connection, Statement statement, ResultSet resultSet)
>         {
>             if (resultSet != null) {
>                 try {
>                     resultSet.close();
>                 } catch (SQLException e) {
>                     throw new RuntimeException(e);
>                 }
>             }
>             if (statement != null) {
>                 try {
>                     statement.close();
>                 } catch (SQLException e) {
>                     throw new RuntimeException(e);
>                 }
>             }
>             if (connection != null) {
>                 try {
>                     connection.close();
>                 } catch (SQLException e) {
>                     throw new RuntimeException(e);
>                 }
>             }
>         }
>     }
> 
>     package com.bjpowernode.oa.utils;
>     
>     import java.sql.*;
>     import java.util.ResourceBundle;
>     
>     public class DBUtil
>     {
>         private static ResourceBundle bundle = ResourceBundle.getBundle("resources.jdbc");
>         private static String driver = bundle.getString("driver");
>         private static String url = bundle.getString("url");
>         private static String user = bundle.getString("user");
>         private static String password = bundle.getString("password");
>         //JDBC工具类
>         static
>         {
>             //注册驱动
>             try
>             {
>     //            Class.forName("com.mysql.jdbc.Driver");//避免写死
>                 Class.forName(driver);
>             }
>             catch (ClassNotFoundException e)
>             {
>                 throw new RuntimeException(e);
>             }
>         }
>         public static Connection getConnection() throws SQLException {
>             //获取链接
>             return DriverManager.getConnection(url,user,password);
>         }
>         //释放资源
>         public static void close(Connection connection, Statement statement, ResultSet resultSet)
>         {
>             if (resultSet != null) {
>                 try {
>                     resultSet.close();
>                 } catch (SQLException e) {
>                     throw new RuntimeException(e);
>                 }
>             }
>             if (statement != null) {
>                 try {
>                     statement.close();
>                 } catch (SQLException e) {
>                     throw new RuntimeException(e);
>                 }
>             }
>             if (connection != null) {
>                 try {
>                     connection.close();
>                 } catch (SQLException e) {
>                     throw new RuntimeException(e);
>                 }
>             }
>         }
>     }