学生选课管理系统（B/S）

package com.xuanke.dao; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class Dao { private Connection conn = null; // private String drivername="com.microsoft.jdbc.sqlserver.SQLServerDriver"; // private String // url="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=xuanke"; private String drivername = "org.gjt.mm.mysql.Driver"; private String url = "jdbc:mysql://localhost:3306/xuanke"; // private String username="sa"; // private String pwd="sa"; private String username = "root"; private String pwd = "root"; PreparedStatement stmt = null; public Dao() { try { Class.forName(drivername).newInstance(); conn = DriverManager.getConnection(url, username, pwd); } catch (InstantiationException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IllegalAccessException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } // ************************用户模块*************************************************************** public boolean userlogin(String username, String password) { boolean res = false;// 默认是登录失败的 ResultSet rs = null; try { stmt = conn .prepareStatement("select * from yonghu where username=? and password=?"); stmt.setString(1, username); stmt.setString(2, password); rs = stmt.executeQuery(); if (rs.next()) { // if(password.equals(rs.getString("password"))) res = true;// 表示登录成功 } else res = false; } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); onclose(); } return res; } // 得到用户级别 0为普通用户 1为管理员用户 // 得到用户级别 0为普通用户 1为管理员用户 public int getstage(String username) { int a = 0; ResultSet rs = null; try { stmt = conn .prepareStatement("select stage from yonghu where username=?"); stmt.setString(1, username); rs = stmt.executeQuery(); if (rs.next()) a = rs.getInt("stage"); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); onclose(); } return a; } public boolean addUser(String username, String password, String stage)// 这个方法返回真值表示注册成功，返回假值表示注册失败 { boolean bo = false;// 表示注册失败 ResultSet res = null; try { stmt = conn .prepareStatement("select * from yonghu where username=?");// 去找用户是否存在 stmt.setString(1, username);// 设定参数username res = stmt.executeQuery(); if (!(res.next()))// 说明用户没有找到 { stmt = conn .prepareStatement("insert into yonghu(username,password,stage) values(?,?,?)");// 插入新用户信息 stmt.setString(1, username);// 参数啊 stmt.setString(2, password);// 还是参数 stmt.setString(3, stage); stmt.execute();// 执行 bo = true;// 表示注册成功 } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); onclose(); } return bo; } public int totalpage() { int totalpage = 0; ResultSet res = null; String sql = "select * from yonghu"; try { stmt = conn.prepareStatement(sql); res = stmt.executeQuery(); if (res.next()) { int x = res.getInt(1); if (x % 10 == 0) { totalpage = x % 10; } else totalpage = x % 10 + 1; } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); onclose(); } return totalpage; } public ResultSet pagers(int topage)// 翻页程序 { ResultSet res = null; try { stmt = conn .prepareStatement("select * from yonghu order by id desc limit ?,10"); stmt.setInt(1, (topage - 1) * 10); res = stmt.executeQuery(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); onclose(); } return res; } public void deleteUser(String username) { try { stmt = conn.prepareStatement("delete from yonghu where username=?"); stmt.setString(1, username); stmt.execute(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); onclose(); } } //*****************学生模块*************************************************************************** public boolean addStudent(String xuehao, String xingming, String sex,String age,String banji)// 这个方法返回真值表示注册成功，返回假值表示注册失败 { boolean bo = false;// 表示注册失败 // ResultSet res = null; try { // stmt = conn // .prepareStatement("select * from student where xuehao=?");// 去找用户是否存在 // stmt.setString(1, xuehao);// 设定参数username // res = stmt.executeQuery(); // if (!(res.next()))// 说明用户没有找到 // { stmt = conn .prepareStatement("insert into student(xuehao,xingming,sex,age,banji) values(?,?,?,?,?)");// 插入新用户信息 stmt.setString(1, xuehao);// 参数啊 stmt.setString(2, xingming);// 还是参数 stmt.setString(3, sex); stmt.setString(4, age); stmt.setString(5, banji); stmt.execute();// 执行 bo = true;// 表示注册成功 // } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); onclose(); } return bo; } public int stutotalpage() { int totalpage = 0; ResultSet res = null; String sql = "select * from student"; try { stmt = conn.prepareStatement(sql); res = stmt.executeQuery(); if (res.next()) { int x = res.getInt(1); if (x % 10 == 0) { totalpage = x % 10; } else totalpage = x % 10 + 1; } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); onclose(); } return totalpage; } public ResultSet stupagers(int topage)// 翻页程序 { ResultSet res = null; try { stmt = conn .prepareStatement("select * from student order by id desc limit ?,10"); stmt.setInt(1, (topage - 1) * 10); res = stmt.executeQuery(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); onclose(); } return res; } public void deleteStu(String xuehao) { try { stmt = conn.prepareStatement("delete from student where xuehao=?"); stmt.setString(1, xuehao); stmt.execute(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); onclose(); } } //****************课程管理************************************* public boolean addCource(String courcename, String teacher, String jiaoshi,String time,float score)// 这个方法返回真值表示注册成功，返回假值表示注册失败 { boolean bo = false;// 表示注册失败 try { stmt = conn .prepareStatement("insert into cource(courcename,teacher,jiaoshi,time,score) values(?,?,?,?,?)");// 插入新用户信息 stmt.setString(1, courcename);// 参数啊 stmt.setString(2, teacher);// 还是参数 stmt.setString(3, jiaoshi); stmt.setString(4, time); stmt.setFloat(5, score); stmt.execute();// 执行 bo = true;// 表示注册成功 } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); onclose(); } return bo; } public int coutotalpage() { int totalpage = 0; ResultSet res = null; String sql = "select * from cource"; try { stmt = conn.prepareStatement(sql); res = stmt.executeQuery(); if (res.next()) { int x = res.getInt(1); if (x % 10 == 0) { totalpage = x % 10; } else totalpage = x % 10 + 1; } } catch (SQLException e) { /