web类的学生成绩管理系统

package com.dao; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; import com.entity.Stu; import com.util.DBconn; public class StuDaoImpl implements StuDao { //1.注册 public boolean register(Stu stu) { boolean flag = false; DBconn.init(); int i =DBconn.addUpdDel("insert into stu(name,pwd,sex,home,grades,info) " + "values('"+stu.getName()+"','"+stu.getPwd()+"','"+stu.getSex()+"','"+stu.getHome()+"','"+stu.getGrades()+"','"+stu.getInfo()+"')"); if(i>0){ flag = true; } DBconn.closeConn(); return flag; } //2.登录(学生与管理员的区别是查找的表不一样) //(学生) public boolean stulogin(String name, String pwd) { boolean flag = false; try { DBconn.init(); ResultSet rs = DBconn.selectSql("select * from stu where name='"+name+"' and pwd='"+pwd+"'"); while(rs.next()){ if(rs.getString("name").equals(name) && rs.getString("pwd").equals(pwd)){ flag = true; } } DBconn.closeConn(); } catch (SQLException e) { e.printStackTrace(); } return flag; } //(管理员) public boolean mgrlogin(String name, String pwd) { boolean flag = false; try { DBconn.init(); ResultSet rs = DBconn.selectSql("select * from mgr where name='"+name+"' and pwd='"+pwd+"'"); while(rs.next()){ if(rs.getString("name").equals(name) && rs.getString("pwd").equals(pwd)){ flag = true; } } DBconn.closeConn(); } catch (SQLException e) { e.printStackTrace(); } return flag; } //3.返回用户信息集合 public List<Stu> getStuAll() { List<Stu> list = new ArrayList<Stu>(); try { DBconn.init(); ResultSet rs = DBconn.selectSql("select * from stu"); while(rs.next()){ Stu stu = new Stu(); stu.setId(rs.getInt("id")); stu.setName(rs.getString("name")); stu.setPwd(rs.getString("pwd")); stu.setSex(rs.getString("sex")); stu.setHome(rs.getString("home")); stu.setGrades(rs.getString("grades")); stu.setInfo(rs.getString("info")); list.add(stu); } DBconn.closeConn(); return list; } catch (SQLException e) { e.printStackTrace(); System.out.print("错误"); } return null; } //4.根据用户名返回某个用户信息集合 public List<Stu> getStuByName(String namestr) { List<Stu> list = new ArrayList<Stu>(); try { DBconn.init(); ResultSet rs = DBconn.selectSql("select * from stu where name='"+namestr+"'"); while(rs.next()){ Stu stu = new Stu(); stu.setId(rs.getInt("id")); stu.setName(rs.getString("name")); stu.setPwd(rs.getString("pwd")); stu.setSex(rs.getString("sex")); stu.setHome(rs.getString("home")); stu.setGrades(rs.getString("grades")); stu.setInfo(rs.getString("info")); list.add(stu); } //DBconn.closeConn(); return list; } catch (SQLException e) { System.out.println("查询的用户可能不存在！"); e.printStackTrace(); }finally{ DBconn.closeConn(); } return null; } //5.根据学号返回某个用户信息集合 public List<Stu> getStuById(String IdStr) { List<Stu> list = new ArrayList<Stu>(); try { DBconn.init(); ResultSet rs = DBconn.selectSql("select * from stu where id='"+IdStr+"'"); while(rs.next()){ Stu stu = new Stu(); stu.setId(rs.getInt("id")); stu.setName(rs.getString("name")); stu.setPwd(rs.getString("pwd")); stu.setSex(rs.getString("sex")); stu.setHome(rs.getString("home")); stu.setGrades(rs.getString("grades")); stu.setInfo(rs.getString("info")); list.add(stu); } DBconn.closeConn(); return list; } catch (SQLException e) { e.printStackTrace(); } return null; } //6.更新用户信息 public boolean update(int id,String name, String pwd,String sex, String home, String grades,String info) { boolean flag = false; DBconn.init(); String sql ="update stu set name ='"+name +"' , pwd ='"+pwd +"' , sex ='"+sex +"' , home ='"+home +"' , grades ='"+grades +"' , info ='"+info+"' where id = "+id; int i =DBconn.addUpdDel(sql); if(i>0){ flag = true; } DBconn.closeConn(); return flag; } //7.根据id删除用户 public boolean delete(int id) { boolean flag = false; DBconn.init(); String sql = "delete from stu where id="+id; int i =DBconn.addUpdDel(sql); if(i>0){ flag = true; } DBconn.closeConn(); return flag; } //8.求成绩总和 public int sum(){ int sum = 0; try { DBconn.init(); ResultSet rs = DBconn.selectSql("SELECT SUM(grades) FROM stu"); while(rs.next()){ System.out.print("进来了1"); if(rs.getInt("SUM(grades)")!=0){ System.out.print("进来了2"); sum = rs.getInt("SUM(grades)"); } } DBconn.closeConn(); return sum; } catch (SQLException e) { e.printStackTrace(); } return 0; } //9.求成绩平均 public int avg(){ int avg = 0; try { DBconn.init(); ResultSet rs = DBconn.selectSql("SELECT AVG(grades) FROM stu"); while(rs.next()){ System.out.print("进来了1"); if(rs.getInt("AVG(grades)")!=0){ System.out.print("进来了2"); avg = rs.getInt("AVG(grades)"); } } DBconn.closeConn(); return avg; } catch (SQLException e) { e.printStackTrace(); } return 0; } }