2020年12月11日

试着写了写，没有遇到问题，明天继续学习java

package Dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import com.sun.org.apache.xerces.internal.impl.xpath.regex.ParseException;

import DBUtil.DBUtil;
import DengBean.BookBean;
import DengBean.DengBean;

public class Dao {
    SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");

    public boolean insert(DengBean bean) {//插入数据的方法
        boolean f=false;
        String sql="insert into deng(id,user,password) values('"+bean.getId()+"','"+bean.getUser()+"','"+bean.getPassword()+"')";
        Connection conn=DBUtil.getConnection();//数据库连接，加载驱动
        Statement state=null;
        try
        {
            state=conn.createStatement();//实例化Statement对象,方便对sql语句进行操作
            System.out.println(conn);
            state.executeUpdate(sql);
            f=true;
            //执行数据库更新操作用于执行INSERT、UPDATE或DELETE语句以及SQLDDL（数据定义语言）语句，
            //例如CREATETABLE和DROPTABLE,（创建表和删除表）
        }catch(Exception e)//当try语句中s出现异常时，会执行catch中的语句
          {
            e.printStackTrace();//捕获异常的语句
          }
         finally //finally作为异常处理的一部分，它只能用在try/catch语句中，并且附带一个语句块，表示这段语句最终一定会被执行（不管有没有抛出异常），经常被用在需要释放资源的情况下。
         {
             DBUtil.close(conn);
         }
        return f;
    }
    
    public boolean delete(int id) {//删除方法
        String sql="delete from deng where id='"+id+"'";
        boolean f=false;
        Connection conn =DBUtil.getConnection();
        Statement st=null;
        try {
            st=conn.createStatement();
            st.executeUpdate(sql);
            f=true;
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        finally{
            DBUtil.close(st, conn);
        }
        return f;
    }
    public boolean login(String user,int password) {
         boolean f=false;
        String sql="select id from deng where username= '"+user+"' and password='"+password+"'";
        
        Connection conn=DBUtil.getConnection();
        Statement st=null;
        List<DengBean> list=new ArrayList<>();
        ResultSet rs=null;
        DengBean bean=null;
        try {
            st=conn.createStatement();
            st.executeQuery(sql);
            rs=st.executeQuery(sql);
            while(rs.next()) {
                int id=rs.getInt("id");
                user = rs.getString("user");
                password=rs.getInt("password");
                bean=new DengBean(id,user,password);
                System.out.print(id+"  ");
                System.out.print(user+"  ");
                System.out.println(password+"  ");
                list.add(bean);
                f=true;
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        finally {
            DBUtil.close(rs, st, conn);
        }
        return f;
        
    }
     public boolean update(DengBean bean) {//更新方法
            String sql="update deng set id='"+bean.getId()+"',user='"+bean.getUser()+"',password='"+bean.getPassword()+"'";
            Connection conn=DBUtil.getConnection();
            boolean f=false;
            Statement st=null;
            try {
                st=conn.createStatement();
                st.executeUpdate(sql);
                f=true;
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return f;
        }
     
     public List<DengBean> list(){//查询所有方法
            String sql="select * from deng order by id ASC";
            Connection conn=DBUtil.getConnection();
            Statement st=null;
            List<DengBean> list=new ArrayList<>();
            ResultSet rs=null;
            DengBean bean=null;
            try {
                st=conn.createStatement();
                st.executeQuery(sql);
                rs=st.executeQuery(sql);
                while(rs.next()) {
                    int id=rs.getInt("id");
                    String user = rs.getString("user");
                    int password=rs.getInt("password");
                    bean=new DengBean(id,user,password);
                    System.out.print(id+"  ");
                    System.out.print(user+"  ");
                    System.out.println(password+"  ");
                    list.add(bean);
                }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            finally {
                DBUtil.close(rs, st, conn);
            }
            return list;
        }
     public List<DengBean> searchById(String a) throws SQLException{//条件查询
         int aa = Integer.parseInt(a);
         String sql="select * from deng where(id like '%"+a+"%')";
            Connection conn=DBUtil.getConnection();
            Statement st=null;
            PreparedStatement pt = conn.prepareStatement(sql);
            List<DengBean> list=new ArrayList<>();
            ResultSet rs=null;
            DengBean bean=null;
            try {
                 pt=conn.prepareStatement(sql);
                 rs=pt.executeQuery();
                while(rs.next()) {
                    int id=rs.getInt("id");
                    String user = rs.getString("user");
                    int password=rs.getInt("password");
                    
                    bean=new DengBean(id,user,password);
                    System.out.print(id+"  ");
                    System.out.print(user+"  ");
                    System.out.println(password+"  ");
                    list.add(bean);
                }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            finally {
                DBUtil.close(rs, st, conn);
            }
            return list;
        }
     
     public List<DengBean> searchByUser(String str) throws SQLException{//条件查询模糊查询
            String sql="select * from deng where(user like '%"+str+"%')";
            Connection conn=DBUtil.getConnection();
            Statement st=null;
            PreparedStatement pt = conn.prepareStatement(sql);
            List<DengBean> list=new ArrayList<>();
            ResultSet rs=null;
            DengBean bean=null;
            try {
                 pt=conn.prepareStatement(sql);
                 rs=pt.executeQuery();
                while(rs.next()) {
                    int id=rs.getInt("id");
                    String user = rs.getString("user");
                    int password=rs.getInt("password");
                    
                    bean=new DengBean(id,user,password);
                    System.out.print(id+"  ");
                    System.out.print(user+"  ");
                    System.out.println(password+"  ");
                    list.add(bean);
                }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            finally {
                DBUtil.close(rs, st, conn);
            }
            return list;
        }
     public  int searchid(String username,int password)
     {
           Connection conn = DBUtil.getConnection();
           Statement state = null;
           ResultSet rs = null;
           int id=0;
           try {
              String sql="select id from deng where username= '"+username+"' and password='"+password+"'";
              state = conn.createStatement();
              rs = state.executeQuery(sql);
              while(rs.next()){
              id = rs.getInt("id");
              }
           }
           catch(SQLException e) {
               e.printStackTrace();
           }
           finally {
               DBUtil.close(state, conn); 
           }
            return id;
     }
     
     public boolean insertbook(BookBean bean) {//插入数据的方法
            boolean f=false;
            String sql="insert into book(id,bookname,date) values('"+bean.getId()+"','"+bean.getBookname()+"','"+bean.getTime()+"')";
            Connection conn=DBUtil.getConnection();//数据库连接，加载驱动
            Statement state=null;
            try
            {
                state=conn.createStatement();//实例化Statement对象,方便对sql语句进行操作
                System.out.println(conn);
                state.executeUpdate(sql);
                f=true;
                //执行数据库更新操作用于执行INSERT、UPDATE或DELETE语句以及SQLDDL（数据定义语言）语句，
                //例如CREATETABLE和DROPTABLE,（创建表和删除表）
            }catch(Exception e)//当try语句中s出现异常时，会执行catch中的语句
              {
                e.printStackTrace();//捕获异常的语句
              }
             finally //finally作为异常处理的一部分，它只能用在try/catch语句中，并且附带一个语句块，表示这段语句最终一定会被执行（不管有没有抛出异常），经常被用在需要释放资源的情况下。
             {
                 DBUtil.close(conn);
             }
            return f;
        }
        
        public boolean deletebook(int id) {//删除方法
            String sql="delete from book where id='"+id+"'";
            boolean f=false;
            Connection conn =DBUtil.getConnection();
            Statement st=null;
            try {
                st=conn.createStatement();
                st.executeUpdate(sql);
                f=true;
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            finally{
                DBUtil.close(st, conn);
            }
            return f;
        }
        
         public boolean updatebook(BookBean bean) {//更新方法
                String sql="update book set id='"+bean.getId()+"',bookname='"+bean.getBookname()+"',date='"+bean.getTime()+"'";
                Connection conn=DBUtil.getConnection();
                boolean f=false;
                Statement st=null;
                try {
                    st=conn.createStatement();
                    st.executeUpdate(sql);
                    f=true;
                } catch (SQLException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                return f;
            }
         
         public List<BookBean> listbook()throws SQLException{//查询所有方法
                String sql="select * from book order by id ASC";
                Connection conn=DBUtil.getConnection();
                Statement st=null;
                List<BookBean> list=new ArrayList<>();
                ResultSet rs=null;
                DengBean bean=null;
                try {
                    st=conn.createStatement();
                    st.executeQuery(sql);
                    rs=st.executeQuery(sql);
                    while(rs.next()) {
                        int id=rs.getInt("id");
                        String bookname = rs.getString("bookname");
                        String time = rs.getString("time");
                        
                        java.sql.Date sqlDate = null;// sql包中的Date
                        try {
                                   
                             java.util.Date utildate = simpleDateFormat.parse(str);
                             sqlDate = new java.sql.Date(utildate.getTime());
                                   
                           } catch (ParseException e) {
                                e.printStackTrace();
                        }
                        bean=new DengBean(id,bookname,);
               
                    }
                } catch (SQLException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                finally {
                    DBUtil.close(rs, st, conn);
                }
                return list;
            }
    public static void main(String[] args) {
        Dao dao=new Dao();
        dao.list();
        System.out.print("chenggg");
    }
}

package DBUtil;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;


public class DBUtil {
    private static String url = "jdbc:mysql://localhost:3306/denglu?useSSL=true&serverTimezone=UTC";
    private static String user = "root";
    private static String password = "789987";
    private static String jdbcName="com.mysql.jdbc.Driver";
    private Connection con=null;
    public static  Connection getConnection() {
        Connection con=null;
        try {
            Class.forName(jdbcName);
            con=DriverManager.getConnection(url, user, password);
            //System.out.println("数据库连接成功");
        } catch (Exception e) {
            // TODO Auto-generated catch block
            //System.out.println("数据库连接失败");
            e.printStackTrace();
        }
        try {
            con = DriverManager.getConnection(url,user,password);
            System.out.println("连接成功");


        } catch (SQLException e) {
            // TODO: handle exception
            e.printStackTrace();
        }
        return con;
    }
    public static void main(String[] args)throws SQLException { 
        Connection conn = getConnection();
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        String sql ="select * from deng";
        pstmt = conn.prepareStatement(sql);
        rs = pstmt.executeQuery();
        System.out.println(getConnection());
        while(rs.next()){
            System.out.println("成功");
        }

        }

       // return con;
        
    
    public static void close(Connection con) {
        if(con!=null)
            try {
                con.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        
    }
    public static void close(Statement state, Connection conn) {
        if(state!=null) {
            try {
                state.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    
    public static void close(ResultSet rs, Statement state, Connection conn) {
        if(rs!=null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(state!=null) {
            try {
                state.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

}

package DengBean;
import java.sql.Date;
public class BookBean {
    private int id;
    private String bookname;
    private Date time;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getBookname() {
        return bookname;
    }
    public void setBookname(String bookname) {
        this.bookname = bookname;
    }
    public Date getTime() {
        return time;
    }
    public void setTime(Date time) {
        this.time = time;
    }
    public BookBean(int id, String bookname, Date time) {
        super();
        this.id = id;
        this.bookname = bookname;
        this.time = time;
    }
    @Override
    public String toString() {
        return "BookBean [id=" + id + ", bookname=" + bookname + ", time=" + time + "]";
    }
    
}

package DengBean;

public class DengBean {
    private int id;
    private String user;
    private int password;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getUser() {
        return user;
    }
    public void setUser(String user) {
        this.user = user;
    }
    public int getPassword() {
        return password;
    }
    public void setPassword(int password) {
        this.password = password;
    }
    public DengBean(int id, String user, int password) {
        super();
        this.id = id;
        this.user = user;
        this.password = password;
    }
    @Override
    public String toString() {
        return "DengBean [id=" + id + ", user=" + user + ", password=" + password + "]";
    }
    
    
    
}

package dengServlet;

import java.io.IOException;
import java.sql.SQLException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import Dao.Dao;
import DengBean.DengBean;



/**
 * Servlet implementation class dengServlet
 */
@WebServlet("/dengServlet")
public class dengServlet extends HttpServlet {
    Dao dao = new Dao();
    private static final long serialVersionUID = 1L;

    /**
     * Default constructor.
     */
    public dengServlet() {
        // TODO Auto-generated constructor stub
    }
    
    
    private void insert(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("utf-8");
        int id = Integer.parseInt(request.getParameter("id"));
        String user = request.getParameter("user");
        int password = Integer.parseInt(request.getParameter("password"));
        DengBean bean = new DengBean(id, user, password);

        if (dao.insert(bean)) {
            request.setAttribute("message", "添加成功");
            request.getRequestDispatcher("index.jsp").forward(request, response);
        }
    }

    private void update(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("utf-8");
        int id = Integer.parseInt(request.getParameter("id"));
        String user = request.getParameter("user");
        int password = Integer.parseInt(request.getParameter("password"));
        /*
        int id = Integer.parseInt(request.getParameter("id"));
        String user = request.getParameter("user");
        int password = Integer.parseInt(request.getParameter("password"));
        DengBean bean = new DengBean(id, user, password);
        */
        DengBean bean = new DengBean(id, user, password);
        dao.update(bean);
        request.setAttribute("message", "修改成功");
        request.getRequestDispatcher("dengServlet?method=list").forward(request, response);
    }

    private void delete(HttpServletRequest request, HttpServletResponse response) throws Exception, IOException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("UTF-8");
        int id = Integer.parseInt(request.getParameter("id"));
        dao.delete(id); // 进行数据库的删除操作
        request.setAttribute("message", "删除成功");
        request.getRequestDispatcher("dengServlet?method=list").forward(request, response);
    }

    private void login(HttpServletRequest request, HttpServletResponse response) throws Exception {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("utf-8");
        List<DengBean> list = dao.list();
        request.setAttribute("list", list);
        request.getRequestDispatcher("list.jsp").forward(request, response);
    }

    private void search(HttpServletRequest request, HttpServletResponse response) throws Exception {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        String cxfs = request.getParameter("cxfs");
        System.out.print(cxfs);
        
        String str = request.getParameter("value");
        
        Dao dao = new Dao();
        List<DengBean> list = null;
        try {
            if ("1".equals(cxfs)) {
                list = dao.searchById(str);
            }
            if ("2".equals(cxfs)) {
                list = dao.searchByUser(str);
            }
        } catch (SQLException e) {
            // TODO 自动生成的 catch 块
            e.printStackTrace();
        }
        request.setAttribute("search", "查询成功");
        request.setAttribute("list", list);
        
        request.getRequestDispatcher("list.jsp").forward(request, response);
    }
    /*
    
    @SuppressWarnings("unused")
    private void login(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        
        
        /*
        String username = request.getParameter("username");
        int password = Integer.parseInt(request.getParameter("password"));
        //int id=dao.searchid(username,password);
        /*
        if(dao.login(username,password)) {
            //dengluchenggong
            req.getSession().setAttribute("message", "登陆成功");
            req.getRequestDispatcher("index.jsp").forward(req, resp);
        }else {
            //denglushibai
            req.getSession().setAttribute("message", "登陆失败");
            req.getRequestDispatcher("index.jsp").forward(req, resp);
        }
        System.out.println(id);
        
        request.setCharacterEncoding("utf-8");
        List<DengBean> list = dao.list();
        request.setAttribute("list", list);
        request.getRequestDispatcher("list.jsp").forward(request, response);
    
        }
*/
    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        String method = request.getParameter("method");
        if ("insert".equals(method)) {
            insert(request, response);
        } else if ("delete".equals(method)) {
            try {
                delete(request, response);
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        } else if ("update".equals(method)) {
            update(request, response);
        } else if ("login".equals(method)) {
            try {
                login(request, response);
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        } else if ("search".equals(method)) {
            try {
                search(request, response);
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<title>用户登录</title>
</head>


<body>
session.setAttribute("user",model);
  <table align="center" border="0px" cellpadding="10px" cellspacing="10px">
  <form action="dengServlet?method=login"  method="post"  >
  <!--  
  <tr>
  <td>用户名：</td>
  <td><input type="text" name="username" id="username"></td>
  </tr>
  <tr>
  <td>密码：</td>
  <td><input type="password" name="password" id="password"></td>
  </tr>
    <tr align="center">
    <th colspan="2">
    -->
    <input type="submit" value="登录"  >
    </th>
    </tr>
  </form>
  </table>
</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<%@include file="sessionCheck.jsp"%>
<% 
Object message =request.getAttribute("message");
if(message!=null&&!"".equals(message)){
%>
    <script type="text/javascript">
    alert("<%=request.getAttribute("message")%>");
    </script>
<%}%>
<div align="center" font-size="30px">
        <h1>用户信息查询系统</h1>
        <div>
            <a  href="insert.jsp">信息登记</a>
        </div>
        <div>
            <a href="dengServlet?method=list">信息修改</a>
        </div>
        <div>
            <a href="dengServlet?method=list">信息删除</a>
        </div>
        <div>
            <a href="dengServlet?method=list">浏览信息</a>
        </div>
        <div>
            <a href="dengServlet?method=list">查询信息</a>
        </div>


</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>添加</title>
</head>
<body>
    <%
        Object message = request.getAttribute("message");
        if (message != null && !"".equals(message)) {
    %>
    <script type="text/javascript">
              alert("<%=request.getAttribute("message")%>"); //弹出对话框
    </script>
    <%
        }
    %>
    <div align="center">
        <h1>添加信息,注册页面</h1>
        <a href="index.jsp">返回主页</a>
       
  <form action="dengServlet?method=insert" method="post">
      <table id="addTable" class="table table-bordered  ">
       <tr class="text-center row">
               <tr> 
                  <td class="col-sm-2">
                    id
                  </td>
                  <td class="col-sm-4">
                   <input type="text" class="form-control"  name="id" id="id" >
                  </td>
              <tr class="text-center row">
                <td class="col-sm-2">
                  账号
                  </td>
                  <td class="col-sm-4">
                   <input type="text" class="form-control"  name="user" id="user" >
                  </td>
              <tr class="text-center row">
                <td class="col-sm-2">
    密码
                  </td>
                  <td class="col-sm-4">
                   <input type="text" class="form-control"  name="password" id="password" >
                  </td>
              <tr class="text-center row">
                <td class="col-sm-2">

            </table>
            <input type="submit" value="添加"  onclick= "return check()" /> 
      </form> 
    </div>
</body>
<script type="text/javascript">
        function check()                        //封装一个<body>中做成点击事件的函数
        {
            if(document.getElementById('id').value=='') {
                  alert('id不能为空！');
                  document.getElementById('area').focus();
                  return false;
                 }
            
            if(document.getElementById('user').value=='') {
                alert('用户名不能为空！');
                document.getElementById('roomnum').focus();
                return false;
               }
            
            if(document.getElementById('password').value=='') {
                alert('密码不能为空！');
                document.getElementById('password').focus();
                return false;
                }
        }
        
        
    </script>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
         Object message = request.getAttribute("search");
         Object grade_list = request.getAttribute("grade_list");
         if(message!=null && !"".equals(message)){     
    %>
         <script type="text/javascript">
              alert("<%=request.getAttribute("search")%>");
         </script>
    <%} %>
        <div align="center">
        <h1 >信息列表</h1>
          <h1> 
        <form action="dengServlet?method=search" method="post">
        <select name="cxfs">
  <option  id="cxfs"value ="1">id</option>
  <option  id="cxfs" value ="2">使用者</option>
  <option  id="cxfs"value="3">密码</option>
</select>
            <input type="text" id="value" name="value" placeholder="请输入条件">
            <input type="submit" id="select" name="select" value="查询" />
      </form>
        
        </h1>
        <a href="index.jsp">返回主页</a>
        <table >
            <tr>
                <td>id</td>
                <td>账户</td>
                <td>密码</td>
                
            </tr>
            <c:forEach items="${list}" var="item">
                <tr>
               
                    <td>${item.id}</td>
                    <td>${item.user}</td>
                    <td>${item.password}</td>
                    
                    <td><a href="update.jsp?id=${item.id}&user=${item.user}&password=${item.password}">修改</a></td>
                    <td><a href="dengServlet?method=delete&id=${item.id}">删除</a></td>
                </tr>
            </c:forEach>
        </table>
    </div> 
</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
Object obj = session.getAttribute("user");
if(obj==null){
out.print("你没有登录");
response.sendRedirect("denglu.jsp");
}else{

}
%>
</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
    <% 
Object message =request.getAttribute("message");
if(message!=null&&!"".equals(message)){
%>
    <script type="text/javascript">
    alert("<%=request.getAttribute("message")%>");
    </script>
    <%}%>
    <div align="center">
        <h1>修改</h1>
        <a href="index.jsp">返回主页</a>
        <form action="dengServlet?method=update" method="post">
            <div>
                id:<input type="text" id="id" name="id" readonly="true" value="${param.id}" />
            </div>
            <div>
                用户:<input type="text" id="user" name="user" value="${param.user}" />
            </div>
            <div>
                密码:<input type="text" id="password" name="password" value="${param.password}"/>
                    
            </div>
            <div>
                <input type="submit" value="修改" onclick="return check()" />
            </div>
</body>
<script type="text/javascript">
        function check()                        //封装一个<body>中做成点击事件的函数
        {
            if(document.getElementById('id').value=='') {
                  alert('id不能为空！');
                  document.getElementById('area').focus();
                  return false;
                 }
            
            if(document.getElementById('user').value=='') {
                alert('用户名不能为空！');
                document.getElementById('roomnum').focus();
                return false;
               }
            
            if(document.getElementById('password').value=='') {
                alert('密码不能为空！');
                document.getElementById('password').focus();
                return false;
                }
        }
</html>