• javaweb-选课系统

    选课系统中用到了4个表，分别是classs、yonghu、teacher、student。在用户中存放管理员的信息name和password以及id，在另三个表中存放对应的数据如图：

    calss：

     teacher：

     student：

    yonghu：

     首先root用户提前定义好名字以及密码，老师和学生可以由root进行增加

    登录时根据选择的用户类型将输入的用户名和密码与数据库中对应的进行判断，根据用户的不同类型跳转到不同的界面。登陆成功后将登录用户的名字存放到session中，之后进行一系列例如更改个人信息、添加课程时直接调用session中的当前用户的名字进行更改。

    下面是代码：

    DAO：

      1 package Dao;
  2 
  3 import java.sql.Connection;
  4 import java.sql.Statement;
  5 import java.util.ArrayList;
  6 import java.util.List;
  7 import java.sql.ResultSet;
  8 import DBUtil.DBUtil;
  9 import Entity.teacher;
 10 import Entity.student;
 11 import Entity.Classs;
 12 public class Dao {
 13     public String dopost(String username,String password,String leibie) {
 14         String i="-1";
 15         String sql=null;
 16         if(leibie.equals("老师"))
 17         {
 18             sql="select * from teacher where xingming = '"+username+"'";
 19         }
 20         else if(leibie.equals("学生"))
 21         {
 22             sql="select * from student where xingming = '"+username+"'";
 23         }
 24         else if(leibie.equals("管理员"))
 25         {
 26             sql="select * from yonghu where name = '"+username+"'";
 27         }
 28         Connection conn = DBUtil.getConn();
 29         Statement state = null;
 30         ResultSet rs = null;
 31         try {
 32             state = conn.createStatement();
 33             rs = state.executeQuery(sql);
 34             while(rs.next()) {
 35                 String password1 = rs.getString("password");
 36                 if(password.equals(password1)) {
 37                     i=rs.getString("id");
 38                 }
 39                 break;
 40             }
 41         }catch (Exception e) {
 42             e.printStackTrace();
 43         } finally {
 44             DBUtil.close(rs,state, conn);
 45         }
 46         return i;
 47     }
 48     public boolean teadd(teacher tea) {
 49 
 50         String sql = "insert into teacher(gonghao,xingbie,xingming,xuexiao,zhicheng,password,id) values('"+ tea.getGonghao() + "','"+ tea.getXingbie() +"','"+ tea.getXingming() +"','" + tea.getXuexiao() +"','"+ tea.getZhicheng() +"' , '"+tea.getPassword()+"' , '"+tea.getId()+"')";
 51         Connection conn = DBUtil.getConn();
 52         Statement state = null;
 53         boolean f = false;
 54         int a = 0;
 55 
 56         try {
 57             state = conn.createStatement();
 58             a=state.executeUpdate(sql);
 59         } catch (Exception e) {
 60             e.printStackTrace();
 61         } finally {
 62 
 63             DBUtil.close(state, conn);
 64         }
 65 
 66         if (a > 0) {
 67             f = true;
 68         }
 69         return f;
 70 
 71     }
 72     public boolean stadd(student stu) {
 73 
 74         String sql = "insert into student(xuehao,xingming,xingbie,banji,zhuanye,password,id) values('"+ stu.getXuehao() + "','"+ stu.getXingming() +"','"+ stu.getXingbie() +"','" + stu.getBanji() +"','"+ stu.getZhuanye() +"' , '"+stu.getPassword()+"' , '"+stu.getId()+"')";
 75         Connection conn = DBUtil.getConn();
 76         Statement state = null;
 77         boolean f = false;
 78         int a = 0;
 79 
 80         try {
 81             state = conn.createStatement();
 82             a=state.executeUpdate(sql);
 83         } catch (Exception e) {
 84             e.printStackTrace();
 85         } finally {
 86 
 87             DBUtil.close(state, conn);
 88         }
 89 
 90         if (a > 0) {
 91             f = true;
 92         }
 93         return f;
 94 
 95     }
 96     public boolean claadd(String bianhao,String name,String number,String prename) {
 97 
 98 
 99         String sql = "insert into classs(clahao,claname,number,tea,num) values('"+ bianhao + "','"+ name +"','"+ number +"','"+prename+"', '0')";
100         Connection conn = DBUtil.getConn();
101         Statement state = null;
102         boolean f = false;
103         int a = 0;
104 
105         try {
106             state = conn.createStatement();
107             a=state.executeUpdate(sql);
108         } catch (Exception e) {
109             e.printStackTrace();
110         } finally {
111 
112             DBUtil.close(state, conn);
113         }
114 
115         if (a > 0) {
116             f = true;
117         }
118         return f;
119 
120     }
121     public boolean teagai(String leibie,String neirong,String prename) {
122     
123         String sql = "update teacher set "+ leibie+" = '"+ neirong+"' "+"where xingming = '"+prename+"'";
124         Connection conn = DBUtil.getConn();
125         Statement state = null;
126         boolean f = false;
127         int a = 0;
128 
129         try {
130             state = conn.createStatement();
131             a=state.executeUpdate(sql);
132         } catch (Exception e) {
133             e.printStackTrace();
134         } finally {
135 
136             DBUtil.close(state, conn);
137         }
138 
139         if (a > 0) {
140             f = true;
141         }
142         return f;
143 
144     }
145     public boolean stugai(String leibie,String neirong,String prename) {
146 
147         String sql = "update student set "+ leibie+" = '"+ neirong+"' "+"where xingming = '"+prename+"'";
148         Connection conn = DBUtil.getConn();
149         Statement state = null;
150         boolean f = false;
151         int a = 0;
152 
153         try {
154             state = conn.createStatement();
155             a=state.executeUpdate(sql);
156         } catch (Exception e) {
157             e.printStackTrace();
158         } finally {
159 
160             DBUtil.close(state, conn);
161         }
162 
163         if (a > 0) {
164             f = true;
165         }
166         return f;
167 
168     }
169     public List<Classs> list(){
170         String sql="select * from classs";
171         Connection conn = DBUtil.getConn();
172         Statement state =null;
173         ResultSet rs = null;
174         List<Classs> list = new ArrayList<>();
175         try {
176             state = conn.createStatement();
177             rs = state.executeQuery(sql);
178             Classs bean = null;
179             while (rs.next()) {
180                 String claname1=rs.getString("claname");
181                 String clahao1=rs.getString("clahao");
182                 String number1=rs.getString("number");
183                 String tea1=rs.getString("tea");
184                 String num1=rs.getString("num");
185                 bean = new Classs(clahao1,claname1,number1,tea1,num1);
186                 list.add(bean);
187                 
188             }
189         
190     }catch (Exception e) {
191         e.printStackTrace();
192     } finally {
193         DBUtil.close(rs,state, conn);
194     }
195     return list;    
196 }
197     public boolean jia(String num,String number,String clahao) {
198         boolean f=false;
199         int n1=Integer.parseInt(num);
200         int n2=Integer.parseInt(number);
201         if(n1<n2) {
202             n1++;
203             String num1=null;
204             num1 = String.valueOf(n1);
205             String sql = "update classs set num = '"+num1+"' where clahao = '"+clahao+"'";
206             Connection conn = DBUtil.getConn();
207             Statement state = null;
208             int a = 0;
209             try {
210                 state = conn.createStatement();
211                 a=state.executeUpdate(sql);
212             } catch (Exception e) {
213                 e.printStackTrace();
214             } finally {
215 
216                 DBUtil.close(state, conn);
217             }
218 
219             if (a > 0) {
220                 f = true;
221             }
222             
223         }
224         return f;
225     }
226 }

    DBUtil：

     1 package DBUtil;
 2 
 3 
 4 import java.sql.Connection;
 5 import java.sql.DriverManager;
 6 import java.sql.PreparedStatement;
 7 import java.sql.ResultSet;
 8 import java.sql.SQLException;
 9 import java.sql.Statement;
10 
11 
12 public class DBUtil {
13 
14     public static String db_url = "**********";
15     public static String db_user = "****";
16     public static String db_pass = "******";
17 
18     public static Connection getConn () {
19         Connection conn = null;
20 
21         try {
22             Class.forName("com.mysql.jdbc.Driver");
23             conn = DriverManager.getConnection(db_url, db_user, db_pass);
24         } catch (Exception e) {
25             e.printStackTrace();
26         }
27 
28         return conn;
29     }//end getConn
30 
31     public static void close (Statement state, Connection conn) {
32         if (state != null) {
33             try {
34                 state.close();
35             } catch (SQLException e) {
36                 e.printStackTrace();
37             }
38         }
39 
40         if (conn != null) {
41             try {
42                 conn.close();
43             } catch (SQLException e) {
44                 e.printStackTrace();
45             }
46         }
47     }
48 
49     public static void close (ResultSet rs, Statement state, Connection conn) {
50         if (rs != null) {
51             try {
52                 rs.close();
53             } catch (SQLException e) {
54                 e.printStackTrace();
55             }
56         }
57 
58         if (state != null) {
59             try {
60                 state.close();
61             } catch (SQLException e) {
62                 e.printStackTrace();
63             }
64         }
65 
66         if (conn != null) {
67             try {
68                 conn.close();
69             } catch (SQLException e) {
70                 e.printStackTrace();
71             }
72         }
73     }
74 
75     public static void main(String[] args) throws SQLException {
76         Connection conn = getConn();
77         PreparedStatement pstmt = null;
78         ResultSet rs = null;
79         String sql ="select * from yonghu";
80         pstmt = conn.prepareStatement(sql);
81         rs = pstmt.executeQuery();
82         if(rs.next()){
83             System.out.println("连接成功");
84         }else{
85             System.out.println("连接失败");
86         }
87     }
88 }

    Entity中定义了4个类：

    classs：

     1 package Entity;
 2 
 3 public class Classs {
 4     private String clahao;
 5     private String claname;
 6     private String number;
 7     private String tea;
 8     private String num;
 9     public String getClahao() {
10         return clahao;
11     }
12     public void setClahao(String clahao) {
13         this.clahao = clahao;
14     }
15     public String getClaname() {
16         return claname;
17     }
18     public void setClaname(String claname) {
19         this.claname = claname;
20     }
21     public String getNumber() {
22         return number;
23     }
24     public void setNumber(String number) {
25         this.number = number;
26     }
27     public String getTea() {
28         return tea;
29     }
30     public void setTea(String tea) {
31         this.tea = tea;
32     }
33     public String getNum() {
34         return num;
35     }
36     public void setNum(String num) {
37         this.num = num;
38     }
39     public Classs(String clahao,String claname,String number, String tea,String num) {
40         super();
41         this.clahao=clahao;
42         this.claname=claname;
43         this.number=number;
44         this.tea=tea;
45         this.num=num;
46     }
47 
48 }

    另外三个是user、teacher、student结构和这个一样就不上了。

    Servlet：

      1 package Servlet;
  2 import java.io.IOException;
  3 import java.util.List;
  4 
  5 import javax.servlet.ServletException;
  6 import javax.servlet.annotation.WebServlet;
  7 import javax.servlet.http.HttpServlet;
  8 import javax.servlet.http.HttpServletRequest;
  9 import javax.servlet.http.HttpServletResponse;
 10 import javax.servlet.http.HttpSession;
 11 import Entity.teacher;
 12 import Entity.User;
 13 import Entity.student;
 14 import Entity.Classs;
 15 import Dao.Dao;
 16 
 17 
 18 
 19 
 20 @WebServlet("/Servlet")
 21 public class Servlet extends HttpServlet {
 22     private static final long serialVersionUID = 1L;
 23 
 24 
 25     public Servlet() {
 26         super();
 27 
 28     }
 29     protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
 30         req.setCharacterEncoding("utf-8");
 31         String method = req.getParameter("method");
 32         if ("dopost".equals(method)) {
 33             dopost(req,resp);
 34         } 
 35         if ("tiao".equals(method)) {
 36             tiao(req,resp);
 37         } 
 38         if ("teadd".equals(method)) {
 39             teadd(req,resp);
 40         } 
 41         if ("stadd".equals(method)) {
 42             stadd(req,resp);
 43         }
 44         if ("claadd".equals(method)) {
 45             claadd(req,resp);
 46         }
 47         if ("teagai".equals(method)) {
 48             teagai(req,resp);
 49         }
 50         if ("stugai".equals(method)) {
 51             stugai(req,resp);
 52         }
 53         if("list".equals(method)){
 54             list(req,resp);
 55         }
 56         if("jia".equals(method)) {
 57             jia(req,resp);
 58         }
 59 
 60     }
 61 
 62 
 63     private void dopost(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
 64 
 65         req.setCharacterEncoding("utf-8");
 66         String username = req.getParameter("username");
 67         String password = req.getParameter("password");
 68         String leibie=req.getParameter("leibie");
 69         HttpSession session = req.getSession();
 70           session.setAttribute("prename",username);
 71         Dao dao=new Dao();
 72         String id=dao.dopost(username, password,leibie);
 73         if(id.equals("-1")) {
 74             req.setAttribute("message", "登录失败！");
 75             req.getRequestDispatcher("index.jsp").forward(req,resp);
 76         }
 77         else if(id.equals("0")) {
 78             req.setAttribute("message", "登陆成功！");
 79             req.getRequestDispatcher("allteacher.jsp").forward(req,resp);
 80         }
 81         else if(id.equals("1")) {
 82             req.setAttribute("message", "登陆成功！");
 83             req.getRequestDispatcher("allstudent.jsp").forward(req,resp);
 84         }
 85         else if(id.equals("2")) {
 86             req.setAttribute("message", "登陆成功！");
 87             req.getRequestDispatcher("root.jsp").forward(req,resp);
 88         }
 89     }
 90     private void tiao(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
 91         req.setCharacterEncoding("utf-8");
 92         String leibie=req.getParameter("leibie");
 93         if(leibie.equals("学生")) {
 94             req.setAttribute("message", "请开始添加学生信息！");
 95             req.getRequestDispatcher("student.jsp").forward(req,resp);
 96         }
 97         if(leibie.equals("老师")) {
 98             req.setAttribute("message", "请添加老师信息！");
 99             req.getRequestDispatcher("teacher.jsp").forward(req,resp);
100         }
101     }
102     private void teadd(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
103         req.setCharacterEncoding("utf-8");
104         String gonghao=req.getParameter("gonghao");
105         String xingming=req.getParameter("xingming");
106         String xingbie=req.getParameter("xingbei");
107         String xuexiao=req.getParameter("xuexiao");
108         String zhicheng=req.getParameter("zhicheng");
109         String password=req.getParameter("password");
110         String id="0";
111         teacher tea=new teacher(gonghao,xingbie,xingming,xuexiao,zhicheng,password,id);
112         Dao dao =new Dao();
113         boolean f=dao.teadd(tea);
114         if(f) {
115             req.setAttribute("message", "添加成功！");
116             req.getRequestDispatcher("root.jsp").forward(req,resp);
117         } else {
118             req.setAttribute("message", "添加失败！");
119             req.getRequestDispatcher("teacher.jsp").forward(req,resp);
120         }
121     }
122     private void stadd(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
123         req.setCharacterEncoding("utf-8");
124         String xuehao=req.getParameter("xuehao");
125         String xingming=req.getParameter("xingming");
126         String xingbie=req.getParameter("xingbei");
127         String banji=req.getParameter("banji");
128         String zhuanye=req.getParameter("zhuanye");
129         String password=req.getParameter("password");
130         String id="1";
131         student stu=new student(xuehao,xingming,xingbie,banji,zhuanye,password,id);
132         Dao dao =new Dao();
133         boolean f=dao.stadd(stu);
134         if(f) {
135             req.setAttribute("message", "添加成功！");
136             req.getRequestDispatcher("root.jsp").forward(req,resp);
137         } else {
138             req.setAttribute("message", "添加失败！");
139             req.getRequestDispatcher("teacher.jsp").forward(req,resp);
140         }
141     }
142     private void claadd(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
143         req.setCharacterEncoding("utf-8");
144         HttpSession session = req.getSession();
145             String prename=null;
146           prename=(String)session.getAttribute("prename");
147         String bianhao=req.getParameter("hao");
148         String name=req.getParameter("name");
149         String number=req.getParameter("number");
150         Dao dao =new Dao();
151         boolean f=dao.claadd(bianhao,name,number,prename);
152         if(f) {
153             req.setAttribute("message", "添加成功！");
154             req.getRequestDispatcher("allteacher.jsp").forward(req,resp);
155         } else {
156             req.setAttribute("message", "添加失败！");
157             req.getRequestDispatcher("addclass.jsp").forward(req,resp);
158         }
159     }
160     private void teagai(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
161         req.setCharacterEncoding("utf-8");
162         HttpSession session = req.getSession();
163             String prename=null;
164           prename=(String)session.getAttribute("prename");
165         String leibie=req.getParameter("leibie");
166         String neirong=req.getParameter("neirong");
167     
168         Dao dao =new Dao();
169         boolean f=dao.teagai(leibie,neirong,prename);
170         if(f) {
171             req.setAttribute("message", "修改成功！");
172             req.getRequestDispatcher("allteacher.jsp").forward(req,resp);
173         } else {
174             req.setAttribute("message", "修改失败！");
175             req.getRequestDispatcher("updatetea.jsp").forward(req,resp);
176         }
177     }
178     private void stugai(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
179         req.setCharacterEncoding("utf-8");
180         HttpSession session = req.getSession();
181             String prename=null;
182           prename=(String)session.getAttribute("prename");
183         String leibie=req.getParameter("leibie");
184         String neirong=req.getParameter("neirong");
185         Dao dao =new Dao();
186         boolean f=dao.stugai(leibie,neirong,prename);
187         if(f) {
188             req.setAttribute("message", "修改成功！");
189             req.getRequestDispatcher("allstudent.jsp").forward(req,resp);
190         } else {
191             req.setAttribute("message", "修改失败！");
192             req.getRequestDispatcher("updatestu.jsp").forward(req,resp);
193         }
194     }
195     private void list(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
196 
197         Dao dao=new Dao();
198         List<Classs> holds = dao.list();
199         req.setAttribute("holds", holds);
200         req.getRequestDispatcher("xuan.jsp").forward(req,resp);
201     }
202     private void jia(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
203         req.setCharacterEncoding("UTF-8");
204         String num=req.getParameter("num");
205         String number=req.getParameter("number");
206         String clahao=req.getParameter("clahao");
207         Dao dao=new Dao();
208         boolean f=dao.jia(num, number, clahao);
209         if(f) {
210             req.setAttribute("message", "选课成功！");
211             req.getRequestDispatcher("allstudent.jsp").forward(req,resp);
212         } else {
213             req.setAttribute("message", "选课失败！");
214             req.getRequestDispatcher("xuan.jsp").forward(req,resp);
215         }
216     }
217 }

    然后就是各个jsp界面了

    index：

     1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 <!DOCTYPE html>
 4 <html>
 5 <head>
 6 <meta charset="UTF-8">
 7 <title>登录</title>
 8 </head>
 9 <body>
10     <%
11         Object message = request.getAttribute("message");
12         if (message != null && !"".equals(message)) {
13     %>
14     <script type="text/javascript">
15               alert("<%=request.getAttribute("message")%>");
16               var  asd=request.getAttribute("username");         
17     </script>
18     <%
19         }
20     %>
21     <form action="Servlet?method=dopost" method="post">
22         <div>
23             用户名<input type="text" name="username" />
24         </div>
25         <div>
26             密码<input type="password" name="password" />
27         </div>
28         <div>
29             <th>类别</th> <select name="leibie">
30                 <option>学生</option>
31                 <option>老师</option>
32                 <option>管理员</option>
33             </select>
34         </div>
35         <div>
36             <input type="submit" value="登录" />
37         </div>
38     </form>
39 </body>
40 </html>

    root：

     1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 <!DOCTYPE html>
 4 <html>
 5 <head>
 6 <meta charset="UTF-8">
 7 <title>当前位置：添加信息</title>
 8 </head>
 9 <body>
10     <%
11         Object message = request.getAttribute("message");
12         if (message != null && !"".equals(message)) {
13     %>
14     <script type="text/javascript">
15               alert("<%=request.getAttribute("message")%>");
16               var  asd=request.getAttribute("username");         
17     </script>
18     <%
19         }
20     %>
21     <form action="Servlet?method=tiao" method="post">
22         <div>
23             <th>类别</th> <select name="leibie">
24                 <option>学生</option>
25                 <option>老师</option>
26             </select>
27         </div>
28         <div>
29             <input type="submit" value="提交" />
30         </div>
31 
32 
33     </form>
34 
35 
36 </body>
37 
38 </html>

    teacher：

    <%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>添加老师信息</title>
</head>
<body>
<%
        Object message = request.getAttribute("message");
        if (message != null && !"".equals(message)) {
    %>
    <script type="text/javascript">
              alert("<%=request.getAttribute("message")%>");
              var  asd=request.getAttribute("name");         
    </script>
    <%
        }
    %>
<form action="Servlet?method=teadd" method="post" >
        <table  >
        
        <tr>
            <th>工号：</th>
            <td>                
                <input name="gonghao" type="text"  />
            </td>
        </tr>
        <tr>
            <th>姓名：</th>
            <td>
                <input name="xingming" type="text" />
            </td>
        </tr>
        <tr>
            <th>性别：</th>
            <td>
                <input name="xingbei" type="radio" value="男" />男
                <input name="xingbei" type="radio" value="女" />女
            </td>
        </tr>
        <tr>
            <th>学校：</th>
            <td>
                <input name="xuexiao" type="text">
            </td>
        </tr>
        <tr>
            <th>职称：</th>
            <td>
                <input name="zhicheng" type="text">                
            </td>
        </tr>
        <tr>
            <th>密码：</th>
            <td>
                <input name="password" type="text">
            </td>
        
        </tr>
        <tr>
            <td >
                <input type="submit" value="提交" />                
            </td>
        </tr>
        
    </table>
        
        


    </form>
</body>
</html>

    student：

    <%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>添加学生信息</title>
</head>
<body>
    <%
        Object message = request.getAttribute("message");
        if (message != null && !"".equals(message)) {
    %>
    <script type="text/javascript">
              alert("<%=request.getAttribute("message")%>");
              var  asd=request.getAttribute("name");         
    </script>
    <%
        }
    %>
    <form action="Servlet?method=stadd" method="post">
        <table>

            <tr>
                <th>学号：</th>
                <td><input name="xuehao" type="text" /></td>
            </tr>
            <tr>
                <th>姓名：</th>
                <td><input name="xingming" type="text" /></td>
            </tr>
            <tr>
                <th>性别：</th>
                <td><input name="xingbei" type="radio" value="男" />男 <input
                    name="xingbei" type="radio" value="女" />女</td>
            </tr>
            <tr>
                <th>班级：</th>
                <td><input name="banji" type="text"></td>
            </tr>
            <tr>
                <th>专业：</th>
                <td><input name="zhuanye" type="text"></td>
            </tr>
            <tr>
                <th>密码：</th>
                <td><input name="password" type="text"></td>
            </tr>
            <tr>
                <td><input type="submit" value="提交" /></td>
            </tr>

        </table>




    </form>
</body>
</html>

    allteacher：

     1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 <!DOCTYPE html>
 4 <html>
 5 <head>
 6 <meta charset="UTF-8">
 7 <title>当前位置：主页</title>
 8 </head>
 9 <body>
10 <%
11         Object message = request.getAttribute("message");
12         if (message != null && !"".equals(message)) {
13     %>
14     <script type="text/javascript">
15               alert("<%=request.getAttribute("message")%>");
16               var  asd=request.getAttribute("username");         
17     </script>
18     <%
19         }
20     %>
21     <% String prename=null;
22     prename=request.getParameter(prename); 
23     %>
24         
25 
26     <div align="center">
27     <div>当前用户：${prename }</div>
28             <div>
29             
30                 <a href="updatetea.jsp">修改个人信息</a> 
31             </div>
32 
33             <div>
34                 <a href="addclass.jsp">添加课程信息</a> 
35         
36             </div>
37 
38     </div>
39 
40 
41 
42 
43 
44 </body>
45 
46 </html>

    allstudent：

     1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
 4 <!DOCTYPE html>
 5 <html>
 6 <head>
 7 <meta charset="UTF-8">
 8 <title>当前位置：主页</title>
 9 </head>
10 <body>
11     <%
12         Object message = request.getAttribute("message");
13         if (message != null && !"".equals(message)) {
14     %>
15     <script type="text/javascript">
16               alert("<%=request.getAttribute("message")%>");
17               var  asd=request.getAttribute("username");         
18     </script>
19     <%
20         }
21     %>
22     <% String prename=null;
23     prename=request.getParameter(prename); 
24     %>
25         
26 
27     <div align="center">
28     <div>当前用户：${prename }</div>
29             <div>
30             
31                 <a href="updatestu.jsp">修改个人信息</a> 
32             </div>
33 
34             <div>
35                 <a href="Servlet?method=list">选课</a> 
36         
37             </div>
38 
39     </div>
40 
41 
42 
43 
44 </body>
45 
46 </html>

    addclass：

     1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 <!DOCTYPE html>
 4 <html>
 5 <head>
 6 <meta charset="UTF-8">
 7 <title>添加老师信息</title>
 8 </head>
 9 <body>
10     <%
11         Object message = request.getAttribute("message");
12         if (message != null && !"".equals(message)) {
13     %>
14     <script type="text/javascript">
15               alert("<%=request.getAttribute("message")%>");
16               var  asd=request.getAttribute("name");         
17     </script>
18     <%
19         }
20     %>
21     <form action="Servlet?method=claadd" method="post">
22         <table>
23 
24             <tr>
25                 <th>课程编号：</th>
26                 <td><input name="hao" type="text" /></td>
27             </tr>
28             <tr>
29                 <th>课程名称：</th>
30                 <td><input name="name" type="text" /></td>
31             </tr>
32             <tr>
33                 <th>选课人数：</th>
34                 <td><input name="number" type="text" /></td>
35             </tr>
36             <tr>
37                 <td><input type="submit" value="提交" /></td>
38             </tr>
39 
40         </table>
41 
42 
43 
44 
45     </form>
46 </body>
47 </html>

    updatestu：

     1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3     <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
 4 <!DOCTYPE html>
 5 <html>
 6 <head>
 7 <meta charset="UTF-8">
 8 <title>Insert title here</title>
 9 </head>
10 <body>
11     <%
12          Object message = request.getAttribute("message");
13          if(message!=null && !"".equals(message)){
14     %>
15          <script type="text/javascript">
16               alert("<%=request.getAttribute("message")%>");
17          </script>
18     <%} %>
19         <% 
20     String prename=null;
21     prename=request.getParameter(prename);
22     %>
23         
24         
25     <div align="center">
26     <div>${prename }</div>
27         <form action="Servlet?method=stugai" method="post" >
28         
29 
30             <div>
31                  <th>类别</th>
32             <select name="leibie">
33                     <option>xuehao</option>
34                     <option>xingming</option>
35                     <option>xingbie</option>
36                     <option>banji</option>
37                     <option>zhuanye</option>
38                 </select>
39             </div>
40             <div>
41                 <input type="text" name="neirong" />
42             </div>
43             
44             <div>
45                 <input type="submit" value="提交" />        
46             </div>
47         </form>
48     </div>    
49 </body>
50 </html>

    updatetea：

     1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 <!DOCTYPE html>
 4 <html>
 5 <head>
 6 <meta charset="UTF-8">
 7 <title>Insert title here</title>
 8 </head>
 9 <body>
10     <%
11          Object message = request.getAttribute("message");
12          if(message!=null && !"".equals(message)){
13     %>
14     <script type="text/javascript">
15               alert("<%=request.getAttribute("message")%>");
16          </script>
17     <%} %>
18     <% 
19     String prename=null;
20     prename=request.getParameter(prename);
21     %>
22     <div align="center">
23     <div>当前用户：${prename }</div>
24         <form action="Servlet?method=teagai" method="post">
25 
26             <div>
27                 <th>类别</th> <select name="leibie">
28                     <option>gonghao</option>
29                     <option>xingming</option>
30                     <option>xingbie</option>
31                     <option>xuexiao</option>
32                     <option>zhicheng</option>
33                 </select>
34             </div>
35             <div>
36                 <input type="text" name="neirong" />
37             </div>
38 
39             <div>
40                 <input type="submit" value="提交" />
41             </div>
42         </form>
43     </div>
44 </body>
45 </html>

    xuan：

     1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 
 4     <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
 5 <!DOCTYPE html>
 6 <html>
 7 <head>
 8 <meta charset="UTF-8">
 9 <title>课程信息</title>
10 </head>
11 <body>
12 <%
13         Object message = request.getAttribute("message");
14         if (message != null && !"".equals(message)) {
15     %>
16     <script type="text/javascript">
17               alert("<%=request.getAttribute("message")%>");
18               var  asd=request.getAttribute("username");         
19     </script>
20     <%
21         }
22     %>
23     <table >
24             <tr>
25                 <td>课程编号</td>
26                 <td>课程名称</td>
27                 <td>任课老师</td>
28                 <td>已选人数</td>
29                 <td>课程人数</td>
30             </tr>
31             <!-- forEach遍历出adminBeans -->
32             <c:forEach items="${holds}" var="item" varStatus="status">
33                 <tr>
34                     <td>${item.clahao}</td>
35                     <td>${item.claname}</td>
36                     <td>${item.tea}</td>
37                     <td>${item.num}</td>
38                     <td>${item.number}</td>
39                     <td><a href="Servlet?method=jia&num=${item.num }&number=${item.number}&clahao=${item.clahao}" >选课</a>   </td>
40                 </tr>
41             </c:forEach>
42         </table>
43 
44 
45 
46 </body>
47 </html>

     这就是全部的代码了，做这个系统的过程中我遇到的难点是如何保持一个用户的登录状态，可以再之后这个用户进行操作时简单便捷的获取当前用户的信息，找了资料之后发现session对象符合我的要求，便开始在我原来的代码上进行更改。最终实现了登录状态的保持。
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  • 原文地址：https://www.cnblogs.com/wyppaa/p/12121691.html
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