JAVA | 学生选课系统

这里使用JAVA语言编写的简易的学生选课系统，展现的都是这个系统核心代码。

其中有不足欢迎批评和指正！

链接数据库的代码

package connection;
//连接数据库student

import java.sql.Connection;
import java.sql.DriverManager;
//import java.sql.Statement;
import java.sql.SQLException;

public class xu{

private static Connection conn = null;
static {
try {
// 注册驱动
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
// 获得一个数据库连接
conn = DriverManager.getConnection("jdbc:sqlserver://localhost:1433;DatabaseName=student","sa","123456");
}catch(ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

public static Connection getConnection() {
return conn;
}
}

选课的操作代码

package connection;

import java.sql.*;
import java.util.*;

public class test1{

private static String ID; // 此处的ID设为全局变量，在下面某些方法里会用到
private static Scanner console = new Scanner(System.in);
private static String managerPass = "123456";
private static Connection conn = xu.getConnection();

public static void main(String [] args) throws SQLException {

System.out.println("Welcome to the student selection system!\n\n"
+"if you are maneger please choose 6、7、8、9、10\n"
+"if you are student Please choose 1、2、3、4、5、10\n");
ShowMenu();
}

public static void ShowMenu() throws SQLException {

System.out.println("-----------option-------------\n");

System.out.println("1--Student login"); // 学生登录
System.out.println("2--Change password"); // 学生修改密码
System.out.println("3--Choose course"); // 学生选课
System.out.println("4--Get course list"); // 学生查看自己的课程表
System.out.println("5--Student rigistration"); // 学生注册账号
System.out.println("6--Create student"); // 管理员创建学生
System.out.println("7--Create course"); // 管理员创建课表
System.out.println("8--Get student list"); // 管理员查看学生表
System.out.println("9--Get course list1"); // 管理员查看选课表里的课程
System.out.println("10--exit\n"); // 退出

Test();
}

public static void Test() throws SQLException {

System.out.println("manager choose 1 ,student choose 0");
int choose1 = console.nextInt(); //int 用nextInt()

if(choose1 == 1) {

System.out.println("Please input your password :");
String password = console.next(); //String 用next()

if(password.equals(managerPass)) {

System.out.println("Welcome manager!\n");
ManagerMenu1();
}

else {

System.out.println("Your password is worry!"); }
}

else if(choose1 == 0) {

System.out.println("Welcome Student!");
StudentMenu1();
}
}

/*管理员操作菜单*/
public static void ManagerMenu1() throws SQLException {

System.out.println("----------Manager----------\n");
System.out.println("Please choose option");
int choose2 = console.nextInt();

switch(choose2) {

case 1 :
case 2 :
case 3 :
case 4 :
case 5 :
System.out.println("This is student`s option,try again!");
ManagerMenu1();
break;
case 6 : CreateStu();break;
case 7 : CreateCourse();break;
case 8 : GetStudentList();break;
case 9 : GetCourseList1();break;
case 10 : System.exit(0);break;
default : System.out.println("Please input an right number , try again!"); ManagerMenu1();

}
}

/*学生操作菜单*/
public static void StudentMenu1() throws SQLException {

System.out.println("----------Student----------\n");
System.out.println("Please input option");
int choose3 = console.nextInt();

switch(choose3) {

case 1 : StuLogin();break;
case 2 : ChangePass();break;

//在进行Choose course,Get course list之前都要求学生进行StuLogin操作

case 3 :
case 4 : System.out.println("you must login before you can do it!\n");StuLogin();break;
case 5 : StuRigistration();break;
case 6 :
case 7 :
case 8 :
case 9 : System.out.println("This is manager`s option,try again!");StudentMenu1();break;
case 10 : System.exit(0);break;
default : System.out.println("Please input an right number,try again!");StudentMenu1();

}
}

/*管理员创建课程*/
public static void CreateCourse() throws SQLException{

try {
/* 通过connection数据库链接对象 创建一个statement对象数据库操作对象,stat对象再获取一个执行sql的语句。
* stat对象就是java程序与Database的一个连接通道*/

Statement stat = conn.createStatement();
String sql1 = "insert into course(couID,couName,couTeacher)values(1,'软件工程','黄伟国')";
String sql2 = "insert into course(couID,couName,couTeacher)values(2,'数据库','韦美雁')";
String sql3 = "insert into course(couID,couName,couTeacher)values(3,'算法设计','黎明')";
String sql4 = "insert into course(couID,couName,couTeacher)values(4,'大学英语','章琴')";
String sql5 = "insert into course(couID,couName,couTeacher)values(5,'Java','唐雅媛')";

int a = stat.executeUpdate(sql1);
int b = stat.executeUpdate(sql2);
int c = stat.executeUpdate(sql3);
int d = stat.executeUpdate(sql4);
int e = stat.executeUpdate(sql5);

int sum = a + b + c + d + e;
System.out.println("成功添加"+ sum + "行课程数据");
ManagerMenu1();

} catch (SQLException e) {
// TODO Auto-generated catch block
// e.printStackTrace();
System.out.println("Course already exists");

ManagerMenu1();
}
}

/*管理员创建学生*/
public static void CreateStu() throws SQLException {

try {
Statement stat = conn.createStatement();
String sql1 = "insert into student(stuID,stuName) Values(20160501,'徐明正')";

// 这里对学生信息的输入也必须一个一个输入，这是系统的缺陷，问题待解决

int a = stat.executeUpdate(sql1);
System.out.println("成功添加"+ a + "行学生数据");
ManagerMenu1();

}catch(SQLException e) {
// TODO Auto-generated catch block
System.out.println("The student already exists");

ManagerMenu1();
}
}

/*学生登录*/
public static void StuLogin() throws SQLException {

System.out.println("Please input your stuID"); // 输入账号
ID = console.next();

System.out.println("Please input your Password"); // 输入密码
String stuPassword = console.next();

String stuID = null;
String Password = null;

Statement stat ;
ResultSet rs ;

try {
stat = conn.createStatement();
String sql1 = "select * from login "; /* 从login表中查询其所有属性值，则stuID 和 Password都有了。
rs是结果集。查询出的记录是一个列表，初始时指针指向的是第一条记录之前的。*/
boolean flag;
rs = stat.executeQuery(sql1);

while(flag = rs.next()) { // rs.next(); //返回值为true or false

stuID = rs.getString("stuID");
Password = rs.getString("Password");

if( ID.equals(stuID) && stuPassword.equals(Password)) // 注意这里，跳出循环的条件很重要

break;

// 如果在数据库里没有找到与用户输入的stuID和Password相匹配的stuID和Password,flag则变为false

}

if(!flag){ // 当flag 为 false 时

System.out.println("The ID or Password is worry!Please input your ID and Password again\n");
StuLogin();
}

else {
System.out.println("***"+ID+"***"+stuID +"***"+stuPassword+"***"+Password+"***");

System.out.println("Login Successful!\n");
System.out.println("------------------Please choose option------------------\n"
// +"If you want to Change Password ,Please choose 2\n"
+"If you want to Choose Course,Please choose 3\n"+"If you want to Get Course List,Please choose 4\n"
+"If you want to exit ,Please choose 8\n");

int choose4 = console.nextInt();

switch(choose4) {

// case 2 : ChangePass();break;
case 3 : ChooseCourse();break;
case 4 : GetCourseList();break;
case 10 : System.exit(0);break;
default : System.out.println("You input an invalid number!");

}

}

} catch (SQLException e) {

// TODO Auto-generated catch block
e.printStackTrace();
}

}

/*在这里说明一下 方法execute 、executeQuery、executeUpdate三者的区别
* 方法executeQuery 用于单个结果集的语句，如select。他会把查询的结果放入ResultSet类对象中供使用。
* 方法executeUpdate 用于执行insert、update或delete语句<返回值为整数>以及SQL DDL（数据定义语言），如create table 和 drop table <返回值为零>。
* 方法execute 用于执行返回多个结果集、多个更新计数或二者组合的语句。*/

/*学生修改密码*/
public static void ChangePass() throws SQLException {

// System.out.println(ID);

/*此处的ID应该必须要重新输入，否则当选择对数据库中某个ID更新的Password进行修改时，没有对应的ID*/

System.out.println("Please input your ID");
String ID = console.next();
System.out.println("Please input your new Password");
String NewPassword = console.next();

Statement stat ;

try {

stat = conn.createStatement(); // 两种写法都可以
// stat = conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
String sql ="UPDATE login SET Password =" + "" + NewPassword + " where stuID ="+ ID;

//注意，此处的NewPassword 和 ID 没有要用''括起来

// String sql1 ="UPDATE login SET Password = 111 where stuID = 20156022";

int a = stat.executeUpdate(sql);
System.out.println(a);

if(a != 0) {

System.out.println("成功修改"+a+"行记录");
System.out.println("Your new Password is "+ NewPassword);

StudentMenu1();
}

else System.out.println("\n"+"Changing the Password is failed!");

}catch(SQLException e) {

// TODO Auto-generated catch block
e.printStackTrace();
}

}

/*学生选课*/
public static void ChooseCourse() throws SQLException {

System.out.println(ID);
String couID = null;
String couName = null;
String couTeacher = null;

Statement stat;
ResultSet rs;

try {

stat = conn.createStatement();
String sql = "select * from course";
rs = stat.executeQuery(sql);

System.out.println("--------可选课程的信息-------");
while(rs.next()) {

couID = rs.getString("couID");
couName = rs.getString("couName");
couTeacher = rs.getString("couTeacher");

System.out.println(couID + " " + couName + " " + couTeacher);
}

System.out.println("\n Please choose your course \n");

stat= conn.createStatement();

// 此处stuID固定位学生登录时所用的ID,这样可以保证登录自己的账号却能选别的账号的课程

System.out.println("input CourseID");
int ID1 = console.nextInt();
int ID2 = console.nextInt();
int ID3 = console.nextInt();

// 这样写 ，学生选课的数目必须固定为3门，问题待解决

String sql1 = "insert into stuCourse(stuID,couID1,couID2,couID3)VALUES(" + ID + ","+ ID1 + "," + ID2 + "," +ID3 +")";
int i = stat.executeUpdate(sql1);

if(i != 0) {
System.out.println("成功选入课程");

GetCourseList();
}
else System.out.println("选课错误");

} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

/*学生获取已选课程列表*/
public static void GetCourseList() throws SQLException {

System.out.println("\nHere is your course that you have choose\n");

Statement stat = null;
ResultSet rs = null;

try {

stat = conn.createStatement();
String sql = "select * from stuCourse ";
rs = stat.executeQuery(sql);

String stuID = null;
String couID1 = null;
String couID2 = null;
String couID3 = null;
String couID4 = null;

while(rs.next()) {

stuID = rs.getString("stuID");
couID1 = rs.getString("couID1");
couID2 = rs.getString("couID2");
couID3 = rs.getString("couID3");
couID4 = rs.getString("couID4");

if(stuID.equals(ID))

System.out.println(stuID + " " + couID1 + " " + couID2 + " " + couID3 + " " + couID4 + "\n");

}

}catch(SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

/*学生注册*/
public static void StuRigistration() throws SQLException{

System.out.println("Please input your ID ");
String ID = console.next();
System.out.println("Please input your Password");
String Password = console.next();

try {
Statement stat = conn.createStatement();
String sql1 = "insert into login(stuID,Password)Values(" + ID + ", " + Password + ")";
//这里密码只能输入数字,问题待解决

int a = stat .executeUpdate(sql1);
System.out.println("成功注册"+ a +"个账号");

StudentMenu1();

}catch(SQLException e) {
// TODO Auto-generated catch block
System.out.println("ID already exists");
}
}

/* 管理员查看学生表 */
public static void GetStudentList() {

System.out.println("\n Here is student` information \n");

Statement stat = null;
ResultSet rs = null;

try {

stat = conn.createStatement();
String sql = "select * from student ";
rs = stat.executeQuery(sql);

String stuID = null;
String stuName = null;

while(rs.next()) {

stuID = rs.getString("stuID");
stuName= rs.getString("stuName");

System.out.println(stuID + " " + stuName + "\n");

ManagerMenu1();
}

}catch(SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

/* 管理员查看选课表里的课程*/
public static void GetCourseList1() {

System.out.println("\n Here is course`information \n");

Statement stat = null;
ResultSet rs = null;

try {

stat = conn.createStatement();
String sql = "select * from course ";
rs = stat.executeQuery(sql);

String couID = null;
String couName = null;
String couTeacher = null;

while(rs.next()) {

couID = rs.getString("couID");
couName = rs.getString("couName");
couTeacher = rs.getString("couTeacher");

System.out.println(couID + " " + couName + " " + couTeacher + "\n");

ManagerMenu1();
}

}catch(SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}