JAVA分级测试——选课系统（补发）
作者：互联网
博客园似乎上传图片多了之后会出现各种问题，所以只能直接上代码了
1 <!DOCTYPE HTML> 2 <html lang="zh"> 3 <head> 4 <meta charset="UTF-8"> 5 <title>石家庄铁道大学学生选课系统</title> 6 <link rel="stylesheet" type="text/css" href="css/login®ister.css"> 7 <link rel="icon" type="image/x-ico" href="images/stu.ico"> 8 </head> 9 <body> 10 <!--Header--> 11 <header> 12 <nav> 13 <ul> 14 <a href="Login.html"><li>首页</li></a> 15 </ul> 16 </nav> 17 </header> 18 19 <!--Main--> 20 <main> 21 <div class="container"> 22 <img class="login_bg" src="images/login.png"> 23 <form class="form" action="LoginServlet" method="post"> 24 <h3>学生选课管理系统</h3> 25 用户类别:<select name="UserSort" size="1"> 26 <option value="1">学生</option> 27 <option value="2">教师</option> 28 <option value="3">管理员</option> 29 </select> 30 <input type="text" autofocus="autofocus" name="username" value="" placeholder="用户名" required="required"> 31 <input type="password" name="password" value="" placeholder="密码" required="required"> 32 <input id="submit" type="submit" name="submit" value="登录"> 33 <input id="submit" type="reset" name="submit" value="清空"> 34 </form> 35 </div> 36 </main> 37 38 <!--Footer--> 39 <footer> 40 <div class="info"> 41 <ul> 42 <a href="#"><li>学生选课管理系统</li></a> 43 <a href="#"><li>帮助与反馈</li></a> 44 </ul> 45 </div> 46 <div class="copyright"> 47 © Copyright. All rights reserved. Design by <a href="http://www.github.com/Soarkey/">Soarkey</a> 48 </div> 49 </footer> 50 </body> 51 </html>Login.html
1 <%@ page language="java" contentType="text/html; charset=UTF-8"
2 pageEncoding="UTF-8"%>
3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
4 <html>
5 <head>
6 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
7 <title>Insert title here</title>
8 <script type="text/javascript">
9 alert("${message}"); /* 提示信息 */
10 document.location.href='${url}'; /* 页面转换 */
11 </script>
12 </head>
13 <body>
14
15 </body>
16 </html>
message.jsp
1 <%@page import="bean.User"%>
2 <%@ page language="java" contentType="text/html; charset=UTF-8"
3 pageEncoding="UTF-8"%>
4 <!DOCTYPE html>
5 <html lang="zh">
6 <head>
7 <meta charset=UTF-8>
8 <title>错误信息</title>
9 <link rel="stylesheet" type="text/css" href="css/message.css">
10 <link rel="icon" type="image/x-ico" href="images/stu.ico">
11 </head>
12 <body>
13 <main>
14 <div class="message">
15 <div class="left">
16 <%
17 //获取提示信息
18 String info = (String) request.getAttribute("info");
19 //如果提示信息不为空，则输出
20 if(info != null){
21 %>
22 <h3><%=info%></h3>
23 <%
24 }
25 //获取登录成功的用户信息
26 User user = (User) session.getAttribute("user");
27 //判断用户是否登录
28 if(user != null){
29
30 }else{
31 //out.print("<script>alert('对不起！您还未登录！');</script>");
32 %>
33 <p><%="对不起！您还未登录！"%></p>
34 <%
35 }
36 %>
37 </div>
38 <div class="right">
39 <a class="relogin" href="Login.html">重新登录></a>
40 </div>
41 </div>
42 </main>
43
44 <footer>
45 <div class="info">
46 <ul>
47 <a href="#"><li>学生选课管理系统</li></a>
48 <a href="#"><li>联系我们</li></a>
49 </ul>
50 </div>
51 <div class="copyright">
52 © Copyright. All rights reserved. Design by <a href="http://www.github.com/Soarkey/">Soarkey</a>
53 </div>
54 </footer>
55 </body>
56 </html>
error.jsp
1 <%@page import="bean.User"%>
2 <%@ page language="java" contentType="text/html; charset=UTF-8"
3 pageEncoding="UTF-8"%>
4 <!DOCTYPE html>
5 <html>
6 <head>
7 <meta charset="UTF-8">
8 <title>管理员后台界面</title>
9 <link rel="stylesheet" type="text/css" href="css/user&admin.css">
10 <link rel="icon" type="image/x-ico" href="images/stu.ico">
11 </head>
12 <body>
13 <header>
14 <div class="title">
15 <span>管理员操作界面</span>
16 </div>
17 <nav>
18 <div class="userinfo">
19 <ul>
20 <li>${UNAME}</li>
21 <li><a href="UserExitServlet">退出登录</a></li>
22 </ul>
23 </div>
24 </nav>
25 </header>
26
27 <main>
28 <div class="container">
29 <div class="select">
30 <h3>请选择操作</h3>
31 <ul id="accordion" class="accordion">
32 <li>
33 <div id="user-info" class="link">教师信息管理</div>
34 <ul class="submenu">
35 <li><a onclick="show_insert_user()">新增教师信息</a></li>
36 </ul>
37 </li>
38 <li>
39 <div class="link">学生信息管理</div>
40 <ul class="submenu">
41 <li><a onclick="show_insert_student()">新增学生信息</a></li>
42 </ul>
43 </li>
44 </ul>
45 </div>
46 <div id="result" class="result">
47 <p class="welcome">欢迎使用学生选课管理系统！</p>
48 </div>
49 </div>
50 </main>
51
52 <footer>
53 <div class="copyright">
54 © Copyright. All rights reserved. Design by <a href="http://www.github.com/Soarkey/">Soarkey</a>
55 </div>
56 </footer>
57
58 <script src="js/jquery-3.1.1.min.js"></script>
59 <script src="js/admin.js"></script>
60 </body>
61 </html>
A_Home.jsp
1 <%@ page language="java" contentType="text/html; charset=UTF-8"
2 pageEncoding="UTF-8"%>
3 <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
4 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
5 <html>
6 <head>
7 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
8 <title>Insert title here</title>
9 </head>
10 <body bgcolor="#e5eecc">
11 <form name="Seekfrom"
12 action="${pageContext.request.contextPath}/ElectCourseServlet"
13 method="post" target="_self">
14 <table align="center">
15 <tr>
16 <td align="center" colspan="4">
17 <h3>搜索课程</h3>
18 <hr>
19 </td>
20 </tr>
21 <tr>
22 <td><input name="seek" type="radio" value="模糊查询" checked>模糊查询
23 <input name="seek" type="radio" value="精确查询">精确查询</td>
24 <td width="80px"><select name="select">
25 <option>名称</option>
26 <option>编号</option>
27 <option>授课教师</option>
28 </select></td>
29 <td><input type="text" name="name" /></td>
30 <td align="center" colspan="2"><input type="submit"
31 value="搜 索"></td>
32 </tr>
33 </table>
34 </form>
35 <br>
36 <table align="center" width="1000" border="1">
37 <tr>
38 <td align="center" ><b>课程信息</b></td>
39 </tr>
40 </table>
41 <table align="center" width="1000" border="1" height="120"
42 cellpadding="1" cellspacing="1">
43
44 <tr align="center" ">
45 <td><b>编号</b></td>
46 <td><b>名称</b></td>
47 <td><b>上课教师</b></td>
48 <td><b>限制人数</b></td>
49 <td><b>可选人数</b></td>
50 <td><b>是否选修</b>
51 </tr>
52 <c:forEach items="${requestScope.list}" var="c">
53 <tr align="center" bgcolor="white">
54 <td>${c.getCNO()}</td>
55 <td>${c.getCName()}</td>
56 <td>${c.getCTeacher()}</td>
57 <td>${c.getCLimitNum()}</td>
58 <td>${c.getCResidueNum()}</td>
59 <td><a
60 href="${pageContext.request.contextPath}/ElectCourseServlet?id=elect&No=${c.getCNO()}">选修</a></td>
61 </tr>
62 </c:forEach>
63 </table>
64 </body>
65 </html>
ElectCourse.jsp
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 <link rel="stylesheet" type="text/css" href="css/login®ister.css">
9 <link rel="icon" type="image/x-ico" href="images/stu.ico">
10 </head>
11 <body>
12 <body bgcolor="#e5eecc">
13 <form action="${pageContext.request.contextPath}/AddStudent_Servlet"
14 method="post" id="myform">
15 <h3> 添加学生信息：</h3>
16 <table width="650px" border="1" align="center" cellpadding="2"
17 cellspacing="2" bgcolor="#EEE8AA">
18 <tr>
19 <td width="150px" align="center">身 份：</td>
20 <td>学 生</td>
21 </tr>
22 <tr>
23 <td width="150px" align="center"><label for="No">学
24 号：</label></td>
25 <td><input type="text" name="No" size="19" id="No" /></td>
26 </tr>
27 <tr>
28 <td width="150px" align="center"><label for="username">姓
29 名：</label></td>
30 <td><input type="text" name="username" size="19" id="username" /></td>
31 </tr>
32 <tr>
33 <td width="150px" align="center">性 别：</td>
34 <td><input type="radio" name="sex" value='男' checked>男
35 <input type="radio" name="sex" value='女'>女</td>
36 </tr>
37 <tr>
38 <td width="150px" align="center"><label for="class">班 级：</label></td>
39 <td><input type="text" name="class" size="19" id="class" /></td>
40 </tr>
41 <tr>
42 <td width="150px" align="center"><label for="major">专 业：</label></td>
43 <td><input type="text" name="department" size="19"
44 id="department" /></td>
45 </tr>
46 <tr>
47 <td width="150px" align="center"><label for="password">密 码：</label></td>
48 <td><input id="password" name="password" type="password"
49 size="20"></td>
50 </tr>
51 <tr>
52 <td width="150px" align="center"><label for="password_2">确认新密码：</label></td>
53 <td><input type="password" name="password_2" size="20"
54 id="password_2" /></td>
55 </tr>
56 <tr>
57 <td align="center" colspan="2"><input type="submit" value="添加">
58 <input name="reset"
59 type="reset" value="重 置"></td>
60 </tr>
61 </table>
62 </form>
63 </body>
64 </html>
AddStudent.jsp
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>学生选课界面</title>
8 <link rel="stylesheet" type="text/css" href="css/user&admin.css">
9 <link rel="icon" type="image/x-ico" href="images/stu.ico">
10 </head>
11 <body>
12 <header>
13 <div class="title">
14 <span>学生操作界面</span>
15 </div>
16 <nav>
17 <div class="userinfo">
18 <ul>
19 <li>${UNAME}</li>
20 <li><a href="UserExitServlet">退出登录</a></li>
21 </ul>
22 </div>
23 </nav>
24 </header>
25
26 <main>
27 <div class="container">
28 <div class="select">
29 <h3>请选择操作</h3>
30 <ul id="accordion" class="accordion">
31 <li>
32 <div id="user-info" class="link">个人信息管理</div>
33 <ul class="submenu">
34 <li><a href="${pageContext.request.contextPath}/StudentInfoServlet?id=update" target="result" onclick="$('div#result').load(this.href);return false;">修改个人信息</a></li>
35 </ul>
36 </li>
37 <li>
38 <div class="link">课程信息管理</div>
39 <ul class="submenu">
40 <li><a href="${pageContext.request.contextPath}/ElectCourseServlet?id=seekall" target="result" onclick="$('div#result').load(this.href);return false;">选课</a></li>
41 <li><a onclick="show_course_teacher()">查看课程信息</a></li>
42 </ul>
43 </li>
44 </ul>
45 </div>
46 <div id="result" class="result">
47 <p class="welcome">欢迎使用学生选课管理系统！</p>
48 </div>
49 </div>
50 </main>
51
52 <footer>
53 <div class="copyright">
54 © Copyright. All rights reserved. Design by <a href="http://www.github.com/Soarkey/">Soarkey</a>
55 </div>
56 </footer>
57
58 <script src="js/jquery-3.1.1.min.js"></script>
59 <script src="js/admin.js"></script>
60 </body>
61 </html>
S_Home.jsp
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>教师管理界面</title>
8 <link rel="stylesheet" type="text/css" href="css/user&admin.css">
9 <link rel="icon" type="image/x-ico" href="images/stu.ico">
10 </head>
11 <body>
12 <header>
13 <div class="title">
14 <span>教师操作界面</span>
15 </div>
16 <nav>
17 <div class="userinfo">
18 <ul>
19 <li>${UNAME}</li>
20 <li><a href="UserExitServlet">退出登录</a></li>
21 </ul>
22 </div>
23 </nav>
24 </header>
25
26 <main>
27 <div class="container">
28 <div class="select">
29 <h3>请选择操作</h3>
30 <ul id="accordion" class="accordion">
31 <li>
32 <div id="user-info" class="link">个人信息管理</div>
33 <ul class="submenu">
34 <li><a href="${pageContext.request.contextPath}/TeacherInfoServlet?id=update" target="result" onclick="$('div#result').load(this.href);return false;">修改个人信息</a></li>
35 </ul>
36 </li>
37 <li>
38 <div class="link">课程信息管理</div>
39 <ul class="submenu">
40 <li><a onclick="show_insert_course()">新增选课信息</a></li>
41 <li><a onclick="show_course_teacher()">查看课程信息</a></li>
42 </ul>
43 </li>
44 </ul>
45 </div>
46 <div id="result" class="result">
47 <p class="welcome">欢迎使用学生选课管理系统！</p>
48 </div>
49 </div>
50 </main>
51
52 <footer>
53 <div class="copyright">
54 © Copyright. All rights reserved. Design by <a href="http://www.github.com/Soarkey/">Soarkey</a>
55 </div>
56 </footer>
57
58 <script src="js/jquery-3.1.1.min.js"></script>
59 <script src="js/admin.js"></script>
60 </body>
61 </html>
T_Home.jsp
1 <%@ page language="java" contentType="text/html; charset=UTF-8"
2 pageEncoding="UTF-8"%>
3 <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
4 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
5 <html>
6 <head>
7 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
8 <title>Insert title here</title>
9 <link rel="stylesheet"
10 href="http://jqueryvalidation.org/files/demo/site-demos.css">
11
12 <script
13 src="http://static.runoob.com/assets/jquery-validation-1.14.0/lib/jquery.js"></script>
14 <script
15 src="http://static.runoob.com/assets/jquery-validation-1.14.0/dist/jquery.validate.min.js"></script>
16 <script
17 src="http://static.runoob.com/assets/jquery-validation-1.14.0/dist/localization/messages_zh.js"></script>
18 <script type="text/javascript">
19 $().ready(function() {
20 $("#myform").validate({/*表单信息验证*/
21 rules : {
22 username : "required",
23 No : {
24 required : true,
25 digits : true
26 },
27 age : {
28 required : true,
29 digits : true
30 },
31 collage : "required",
32 department : "required",
33 password : "required",
34 password_2 : {
35 required : true,
36 equalTo : "#password"
37 }
38 },
39 messages : {
40 username : {
41 required : "请输入姓名",
42 },
43 No : {
44 required : "请输入学号",
45 digits : "只能输入数字串",
46 },
47 age : {
48 required : "请输入年龄",
49 digits : "只能输入数字串",
50 },
51 collage : {
52 required : "请输入所在学院",
53 },
54 department : {
55 required : "请输入所在专业",
56 },
57 password : {
58 required : "请输入密码",
59 },
60 password_2 : {
61 required : "请确认密码",
62 equalTo : "两次密码输入不一致",
63 }
64 }
65 });
66 });
67 </script>
68 </head>
69 <body>
70 <form
71 action="${pageContext.request.contextPath}/UpdateTeacherInfoServlet"
72 method="post" id="myform">
73 <h3> 修改教师信息：</h3>
74 <table width="650px" border="1" align="center" cellpadding="2"
75 cellspacing="2">
76 <tr>
77 <td width="150px" align="center">身 份：</td>
78 <td>教 师</td>
79 </tr>
80 <tr>
81 <td width="150px" align="center"><label for="No">工
82 号：</label></td>
83 <td>${t.getTNo()}</td>
84 </tr>
85 <tr>
86 <td width="150px" align="center"><label for="username">姓 名：</label></td>
87 <td><input type="text" name="username" size="19" id="username"
88 value="${t.getTName()}" /></td>
89 </tr>
90 <tr>
91 <td width="150px" align="center">性 别：</td>
92 <td><input type="radio" name="sex" value='男' checked>男
93 <input type="radio" name="sex" value='女'>女</td>
94 </tr>
95 <tr>
96 <td width="150px" align="center"><label for="age">专 业：</label></td>
97 <td><input type="text" name="major" size="19" id="age"
98 value="${t.getTMajor()}" /></td>
99 </tr>
100 <tr>
101 <td width="150px" align="center"><label for="collage">职 称：</label></td>
102 <td><input type="text" name="level" size="19" id="collage"
103 value="${t.getTLevel()}" /></td>
104 </tr>
105 <tr>
106 <td width="150px" align="center"><label for="password">新
107 密 码：</label></td>
108 <td><input id="password" name="password" type="password"
109 size="20"></td>
110 </tr>
111 <tr>
112 <td width="150px" align="center"><label for="password_2">确认新密码：</label></td>
113 <td><input type="password" name="password_2" size="20"
114 id="password_2" /></td>
115 </tr>
116 <tr>
117 <td align="center" colspan="2"><input type="submit"
118 value="确认修改"></td>
119 </tr>
120 <tr>
121 <td colspan="2">
122 <font color="red">${message}</font>
123 </td>
124 </tr>
125 </table>
126 </form>
127 </body>
128 </html>
UpdateTeacherInfo.jsp
后台代码：
因为大部分代码都大同小异，只展示选课部分的代码
1 package servlet;
2
3 import java.io.IOException;
4 import java.util.ArrayList;
5 import java.util.List;
6
7 import javax.servlet.ServletException;
8 import javax.servlet.annotation.WebServlet;
9 import javax.servlet.http.HttpServlet;
10 import javax.servlet.http.HttpServletRequest;
11 import javax.servlet.http.HttpServletResponse;
12
13 import bean.Course;
14 import service.CService;
15 import service.EService;
16
17 /**
18 * Servlet implementation class MyCourseServlet
19 */
20 @WebServlet("/ElectCourseServlet")
21 public class ElectCourseServlet extends HttpServlet {
22 private static final long serialVersionUID = 1L;
23
24 /**
25 * @see HttpServlet#HttpServlet()
26 */
27 public ElectCourseServlet() {
28 super();
29 // TODO Auto-generated constructor stub
30 }
31
32 /**
33 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
34 */
35 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
36 // TODO Auto-generated method stub
37 String id = request.getParameter("id");
38 if (id.equals("seekall")) {// 查询所有课程分配
39 List<Course> list = new ArrayList<>();
40 list = new CService().seekAll_C(list);
41 request.setAttribute("list", list); // 把list储存在request对象中
42 request.getRequestDispatcher("/jsp/course/ElectCourse.jsp").forward(request, response);// 转到/AllBookInfo.jsp页面
43 } else if (id.equals("elect")) {// 选课
44 String cNo = request.getParameter("No"); //
45 String sNo = (String) request.getSession().getAttribute("UNAME");
46 String message = "";
47 message = new EService().elect_C(cNo, sNo, message);
48 if (message == null || message.equals("")) {
49 request.getSession().setAttribute("message", "选课成功！");
50 } else {
51 request.getSession().setAttribute("message", message);
52
53 }
54 request.getSession().setAttribute("url", "ElectCourseServlet?id=seekall");
55 response.sendRedirect("Message.jsp");
56 }
57 }
58
59 /**
60 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
61 */
62 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
63 // TODO Auto-generated method stub
64 doGet(request, response);
65 }
66
67 }
ElectCourseServlet.java
1 package service;
2
3 import java.util.ArrayList;
4 import java.util.List;
5
6 import bean.Course;
7 import bean.Student;
8 import dao.ElectCSql;
9 import dao.MinusResidueNumSql;
10 import dao.SeekElectedSql;
11 import service.CService;
12 import service.SService;
13
14 public class EService {
15 public String elect_C(String cNo, String sNo, String message) {
16 List<Course> list = new ArrayList<>();
17 list = new CService().seek_C("编号", "精确查询", cNo, list);// 根据课程编号获得课程名称
18 String cname = ((Course) list.toArray()[0]).getCName();
19 String tname = ((Course) list.toArray()[0]).getCTeacher();
20 List<Student> list2 = new ArrayList<>();
21 list2 = new SService().seek_S("学号", "精确查询", sNo, list2);// 根据学号获得姓名
22 String sname = ((Student) list2.toArray()[0]).getSName();
23 Boolean bool = new SeekElectedSql().seekExist_Sql(cNo, sNo);// 判断该课是否选过
24 if (bool == true) {
25 message = "该课已选，请选其它课";
26 bool = false;
27 } else if (bool == false) {
28 Boolean bool2 = new MinusResidueNumSql().seekResidueNum_Sql(cNo);// 判断可选人数，并修改
29 if (bool2 == true) {
30 bool = new ElectCSql().electC_Sql(cNo, cname, sNo, sname,tname);// 根据课程编号和学号选课
31 } else if (bool2 == false) {
32 message = "该班学生已满，请选其它课";
33 }
34 }
35 return message;
36 }
37 }
EService.java
1 package dao;
2
3 import java.sql.Connection;
4 import java.sql.PreparedStatement;
5
6 import database.MysqlLinking;
7
8 public class ElectCSql {
9 public Boolean electC_Sql(String cNo, String cname, String sNo, String sname,String tname) {
10 (new MysqlLinking()).getLink();// 连接数据库
11 Connection conn = MysqlLinking.conn;// 得到连接数据库的Connection对象
12 Boolean bool = false;
13 if (conn != null) {
14 try {
15 // 插入注册信息的SQL语句(使用?占位符) //添加选课信息
16 String sql = "insert into electcourse (C_No,S_No,T_Name,C_Name,S_Name) values(?,?,?,?,?)";
17 // 创建PreparedStatement对象
18 PreparedStatement ps = conn.prepareStatement(sql);
19 // 对SQL语句中的参数动态赋值
20 ps.setString(1, cNo);
21 ps.setString(2, sNo);
22 ps.setString(3, tname);
23 ps.setString(4, cname);
24 ps.setString(5, sname);
25 // 执行更新操作
26 int count = ps.executeUpdate();
27 if (count >= 1) {
28 bool = true;
29 }
30 } catch (Exception e) {
31 e.printStackTrace();
32 }
33 } else {
34 // 发送数据库连接错误提示信息
35 System.out.println("数据库连接错误！");
36 }
37 return bool;
38 }
39 }
ElectCSql
1 package dao;
2
3 import java.sql.Connection;
4 import java.sql.PreparedStatement;
5 import java.sql.ResultSet;
6
7 import database.MysqlLinking;
8
9 public class MinusResidueNumSql {
10 public Boolean seekResidueNum_Sql(String cNo) {
11 (new MysqlLinking()).getLink();// 连接数据库
12 Connection conn = MysqlLinking.conn;// 得到连接数据库的Connection对象
13 Boolean bool = false;
14 if (conn != null) {
15 try {
16 String sql = "select * from course where C_No=?"; // 根据课程编号查询课程的可选人数
17 PreparedStatement ps = conn.prepareStatement(sql);
18 ps.setString(1, cNo);
19 ResultSet rs = ps.executeQuery();
20 int residueNum = 0;
21 while (rs.next()) {
22 residueNum = Integer.valueOf(rs.getString("C_ResidueNum"));
23 }
24 if (residueNum > 0) {
25 try {
26 String sql_2 = "update course set C_ResidueNum=? where C_No=?";
27 PreparedStatement ps_2 = conn.prepareStatement(sql_2);
28 int re = residueNum - 1;// 课程可选人数减一
29 ps_2.setString(1, String.valueOf(re));
30 ps_2.setString(2, cNo);
31 int count = ps_2.executeUpdate();
32 if (count >= 1) {
33 bool = true;
34 }
35 } catch (Exception e) {
36 e.printStackTrace();
37 }
38 }
39 } catch (Exception e) {
40 e.printStackTrace();
41 }
42 } else {
43 // 发送数据库连接错误提示信息
44 System.out.println("数据库连接错误！");
45 }
46 return bool;
47 }
48 }
MinusResidueNumSql
1 package dao;
2
3 import java.sql.Connection;
4 import java.sql.PreparedStatement;
5 import java.sql.ResultSet;
6 import java.util.List;
7
8 import bean.Course;
9 import database.MysqlLinking;
10
11 public class SeekCSql {
12 public List<Course> seekC_Sql(String select, String seek, String name, List<Course> list) {
13 (new MysqlLinking()).getLink();// 连接数据库
14 Connection conn = MysqlLinking.conn;// 得到连接数据库的Connection对象
15 if (conn != null) {
16 try {
17 String sql = "";
18 PreparedStatement ps = null;
19 if (seek.equals("模糊查询")) {// 条件查询课程
20 sql = "select * from course where " + select + " like '%" + name + "%'";
21 ps = conn.prepareStatement(sql);
22 } else if (seek.equals("精确查询")) {
23 sql = "select * from course where " + select + "=?";
24 // 创建PreparedStatement对象
25 ps = conn.prepareStatement(sql);
26 ps.setString(1, name);
27 }
28 ResultSet rs = ps.executeQuery();
29
30 while (rs.next()) {
31 Course c = new Course();
32 c.setCNO(rs.getString("C_No"));
33 c.setCName(rs.getString("C_Name"));
34 c.setCTeacher(rs.getString("C_Teacher"));
35 list.add(c);
36 }
37 } catch (Exception e) {
38 e.printStackTrace();
39 }
40 } else {
41 // 发送数据库连接错误提示信息
42 System.out.println("数据库连接错误！");
43 }
44 return list;
45 }
46 }
SeekCSql.java
1 package dao;
2
3 import java.sql.Connection;
4 import java.sql.PreparedStatement;
5 import java.sql.ResultSet;
6
7 import database.MysqlLinking;
8
9 public class SeekElectedSql {
10 public Boolean seekExist_Sql(String cNo, String sNo) {
11 (new MysqlLinking()).getLink();// 连接数据库
12 Connection conn = MysqlLinking.conn;// 得到连接数据库的Connection对象
13 Boolean bool = false;
14 if (conn != null) {
15 try {
16 // 插入注册信息的SQL语句(使用?占位符)
17 String sql = "select * from electcourse where C_No=? and S_No=?";// 根据课程编号和学号判断该课是否已选
18 // 创建PreparedStatement对象
19 PreparedStatement ps = conn.prepareStatement(sql);
20 // 对SQL语句中的参数动态赋值
21 ps.setString(1, cNo);
22 ps.setString(2, sNo);
23 // 执行更新操作
24 ResultSet rs = ps.executeQuery();
25 while (rs.next()) {
26 bool = true;
27 }
28 } catch (Exception e) {
29 e.printStackTrace();
30 }
31 } else {
32 // 发送数据库连接错误提示信息
33 System.out.println("数据库连接错误！");
34 }
35 return bool;
36 }
37 }
SeekElectedSql.java
整体项目结构如图：
标签：ps,JAVA,String,选课,java,nbsp,sql,import,补发 来源： https://www.cnblogs.com/wushenjiang/p/12152653.html