JAVA-EE动态展示访问者信息内容的实现------计算机网络经典

傷城~ 2024-02-21 09:27 1阅读 0赞

>     `springbootvue`CREATE DATABASE SpringBootVue;
>     USE SpringBootVue;
>     CREATE TABLE t_movie(id BIGINT PRIMARY KEY AUTO_INCREMENT,title VARCHAR(255),rating DOUBLE);
>     INSERT INTO t_movie(id,title,rating) VALUES(NULL,"金刚狼",8.7);
>     INSERT INTO t_movie(id,title,rating) VALUES(NULL,"变形金刚",8.6)
>     INSERT INTO t_movie(id,title,rating) VALUES(NULL,"蜘蛛侠",8.7)
>     SELECT * FROM t_movie
>     CREATE TABLE dept(deptno INT PRIMARY KEY,dname VARCHAR(255),loc VARCHAR(255))
>     INSERT INTO dept(deptno,dname,loc) VALUES(10,'销售部','北京')
>     INSERT INTO dept(deptno,dname,loc) VALUES(20,'研发部','上海')
>     INSERT INTO dept(deptno,dname,loc) VALUES(30,'技术部','广州')
>     INSERT INTO dept(deptno,dname,loc) VALUES(40,'媒体部','深圳')
>     SELECT * FROM dept
>     INSERT INTO t_movie VALUES(NULL,'asd',2.0)
>     SELECT * FROM t_movie
>     CREATE TABLE t_user(id INT PRIMARY KEY AUTO_INCREMENT,username VARCHAR(255),pssword VARCHAR(255));
>     INSERT INTO t_user(username,pssword) VALUES('admin','123456')
>     INSERT INTO t_user(username,pssword) VALUES('zhangsan','123456')
> 
> \`springbootvue\`CREATE DATABASE SpringBootVue;  
> USE SpringBootVue;  
> CREATE TABLE t\_movie(id BIGINT PRIMARY KEY AUTO\_INCREMENT,title VARCHAR(255),rating DOUBLE);  
> INSERT INTO t\_movie(id,title,rating) VALUES(NULL,"金刚狼",8.7);  
> INSERT INTO t\_movie(id,title,rating) VALUES(NULL,"变形金刚",8.6)  
> INSERT INTO t\_movie(id,title,rating) VALUES(NULL,"蜘蛛侠",8.7)  
> SELECT \* FROM t\_movie  
> CREATE TABLE dept(deptno INT PRIMARY KEY,dname VARCHAR(255),loc VARCHAR(255))  
> INSERT INTO dept(deptno,dname,loc) VALUES(10,'销售部','北京')  
> INSERT INTO dept(deptno,dname,loc) VALUES(20,'研发部','上海')  
> INSERT INTO dept(deptno,dname,loc) VALUES(30,'技术部','广州')  
> INSERT INTO dept(deptno,dname,loc) VALUES(40,'媒体部','深圳')  
> SELECT \* FROM dept  
> INSERT INTO t\_movie VALUES(NULL,'asd',2.0)  
> SELECT \* FROM t\_movie  
> CREATE TABLE t\_user(id INT PRIMARY KEY AUTO\_INCREMENT,username VARCHAR(255),pssword VARCHAR(255));  
> INSERT INTO t\_user(username,pssword) VALUES('admin','123456')  
> INSERT INTO t\_user(username,pssword) VALUES('zhangsan','123456')

>     <%@ page import="com.bjpowernode.oa.web.Pojo.Dept" %>
>     <%@ page import="java.util.List" %>
>     <%@ page contentType="text/html;charset=UTF-8" language="java" %>
>     <%List<Dept> depts = (List)request.getAttribute("dept");%>
>     <!DOCTYPE html>
>     <html>
>     <head>
>         <meta charset="utf-8">
>         <title>部门列表</title>
>     </head>
>     <body>
>     <script>
>         function del(dno){
>             var ok = window.confirm('亲,确认删除该数据吗?');
>             if(ok){
>                 document.location.href = "<%=request.getContextPath()%>/dept/delete?deptno=" + dno;
>             }
>         }
>     </script>
>     <h2>欢迎:<a href=""><%=session.getAttribute("username")%></a></h2>
>     <h1 align="center">部门列表</h1>
>     <hr>
>         <table align="center" border="1px" width="50%">
>             <tr>
>                 <th>序号</th>
>                 <th>部门编号</th>
>                 <th>部门名称</th>
>                 <th>操作</th>
>             </tr>
>             <%
>                 int count = 0;
>                 for(Dept dept : depts)
>                 {
>     
>             %>
>                 <tr>
>                     <td><%=++count%></td>
>                     <td><%=dept.getDeptno()%></td>
>                     <td><%=dept.getDname()%></td>
>                     <td>
>                         <a href="javascript:void(0)" onclick="del(<%=dept.getDeptno()%>)">删除</a>
>                         <a href="<%=(request.getContextPath())%>/dept/detail?f=m&deptno=<%=dept.getDeptno()%>">修改</a>
>                         <a href="<%=(request.getContextPath())%>/dept/detail?f=d&deptno=<%=dept.getDeptno()%>">详情</a>
>                     </td>
>                 </tr>
>             <%
>                 }
>             %>
>     
>         </table>
>         <hr>
>         <a href="<%=(request.getContextPath())%>/add.jsp">新增部门</a>
>     </body>
>     </html>
> 
>     <%@ page import="com.bjpowernode.oa.web.Pojo.Dept" %>
>     <%@ page import="java.util.List" %>
>     <%@ page contentType="text/html;charset=UTF-8" language="java" %>
>     <%List<Dept> depts = (List)request.getAttribute("dept");%>
>     <!DOCTYPE html>
>     <html>
>     <head>
>         <meta charset="utf-8">
>         <title>部门列表</title>
>     </head>
>     <body>
>     <script>
>         function del(dno){
>             var ok = window.confirm('亲,确认删除该数据吗?');
>             if(ok){
>                 document.location.href = "<%=request.getContextPath()%>/dept/delete?deptno=" + dno;
>             }
>         }
>     </script>
>     <h2>欢迎:<a href=""><%=session.getAttribute("username")%></a></h2>
>     <h1 align="center">部门列表</h1>
>     <hr>
>         <table align="center" border="1px" width="50%">
>             <tr>
>                 <th>序号</th>
>                 <th>部门编号</th>
>                 <th>部门名称</th>
>                 <th>操作</th>
>             </tr>
>             <%
>                 int count = 0;
>                 for(Dept dept : depts)
>                 {
>     
>             %>
>                 <tr>
>                     <td><%=++count%></td>
>                     <td><%=dept.getDeptno()%></td>
>                     <td><%=dept.getDname()%></td>
>                     <td>
>                         <a href="javascript:void(0)" οnclick="del(<%=dept.getDeptno()%>)">删除</a>
>                         <a href="<%=(request.getContextPath())%>/dept/detail?f=m&deptno=<%=dept.getDeptno()%>">修改</a>
>                         <a href="<%=(request.getContextPath())%>/dept/detail?f=d&deptno=<%=dept.getDeptno()%>">详情</a>
>                     </td>
>                 </tr>
>             <%
>                 }
>             %>
>     
>         </table>
>         <hr>
>         <a href="<%=(request.getContextPath())%>/add.jsp">新增部门</a>
>     </body>
>     </html>

>     <%@ page contentType="text/html;charset=UTF-8" language="java" %>
>     <%--访问JSP不允许生成Session对象--%>
>     <%@ page session="false" %>
>     <!DOCTYPE html>
>     <html>
>     <head>
>         <meta charset="utf-8">
>         <title>欢迎页</title>
>     </head>
>     <body>
>         <h1>用户登录</h1>
>         <hr>
>         <form action="<%=request.getContextPath()%>/user/login" method="post">
>             username:<input type="text" name="username"><br>
>             password:<input type="password" name="password"><br>
>             <input type="submit" value="login">
>         </form>
>     <%--    前端发送请求路径的时候,如果请求路径是绝对路径,要以/开始,加项目名--%>
>     <%--    <h1><a href="<%=(request.getContextPath())%>/dept/list">查看部门列表</a></h1>--%>
>     </body>
>     </html>
> 
>     <%@ page contentType="text/html;charset=UTF-8" language="java" %>
>     <%--访问JSP不允许生成Session对象--%>
>     <%@ page session="false" %>
>     <!DOCTYPE html>
>     <html>
>     <head>
>         <meta charset="utf-8">
>         <title>欢迎页</title>
>     </head>
>     <body>
>         <h1>用户登录</h1>
>         <hr>
>         <form action="<%=request.getContextPath()%>/user/login" method="post">
>             username:<input type="text" name="username"><br>
>             password:<input type="password" name="password"><br>
>             <input type="submit" value="login">
>         </form>
>     <%--    前端发送请求路径的时候,如果请求路径是绝对路径,要以/开始,加项目名--%>
>     <%--    <h1><a href="<%=(request.getContextPath())%>/dept/list">查看部门列表</a></h1>--%>
>     </body>
>     </html>

>     package com.bjpowernode.oa.web.action;
>     
>     import com.bjpowernode.oa.utils.DBUtil;
>     import com.bjpowernode.oa.web.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 jakarta.servlet.http.HttpSession;
>     
>     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
>         {
>             HttpSession session = request.getSession(false);
>             String servletPath = request.getServletPath();
>             if(session != null && session.getAttribute("username") != null)
>             {
>                 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);
>                 }
>             }
>             else
>             {
>                 response.sendRedirect(request.getContextPath() + "/index.jsp");
>             }
>         }
>     
>         private void doModify(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             request.setCharacterEncoding("UTF-8");
>             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
>         {
>             request.setCharacterEncoding("UTF-8");
>             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("dept",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.web.action;
>     
>     import com.bjpowernode.oa.utils.DBUtil;
>     import com.bjpowernode.oa.web.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 jakarta.servlet.http.HttpSession;
>     
>     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
>         {
>             HttpSession session = request.getSession(false);
>             String servletPath = request.getServletPath();
>             if(session != null && session.getAttribute("username") != null)
>             {
>                 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);
>                 }
>             }
>             else
>             {
>                 response.sendRedirect(request.getContextPath() + "/index.jsp");
>             }
>         }
>     
>         private void doModify(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             request.setCharacterEncoding("UTF-8");
>             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
>         {
>             request.setCharacterEncoding("UTF-8");
>             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("dept",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.web.action;
>     
>     import com.bjpowernode.oa.utils.DBUtil;
>     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 jakarta.servlet.http.HttpSession;
>     
>     import java.io.IOException;
>     import java.sql.Connection;
>     import java.sql.PreparedStatement;
>     import java.sql.ResultSet;
>     import java.sql.SQLException;
>     
>     @WebServlet("/user/login")
>     public class UserServlet extends HttpServlet
>     {
>         @Override
>         protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             request.setCharacterEncoding("UTF-8");
>             String username = request.getParameter("username");
>             String password = request.getParameter("password");
>             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("username",username);
>                 response.sendRedirect(request.getContextPath() + "/dept/list");
>             }
>             else
>             {
>                 response.sendRedirect(request.getContextPath() + "/Error.jsp");
>             }
>         }
>     }
> 
>     package com.bjpowernode.oa.web.action;
>     
>     import com.bjpowernode.oa.utils.DBUtil;
>     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 jakarta.servlet.http.HttpSession;
>     
>     import java.io.IOException;
>     import java.sql.Connection;
>     import java.sql.PreparedStatement;
>     import java.sql.ResultSet;
>     import java.sql.SQLException;
>     
>     @WebServlet("/user/login")
>     public class UserServlet extends HttpServlet
>     {
>         @Override
>         protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             request.setCharacterEncoding("UTF-8");
>             String username = request.getParameter("username");
>             String password = request.getParameter("password");
>             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("username",username);
>                 response.sendRedirect(request.getContextPath() + "/dept/list");
>             }
>             else
>             {
>                 response.sendRedirect(request.getContextPath() + "/Error.jsp");
>             }
>         }
>     }