logindao.java

我实习时候的设计

package cn.yxh.dao;

import java.sql.*;

import cn.yxh.util.DBConn;

public class LoginDAO {
	//检验登陆的方法
	public static boolean checkLogin(String username,String password,String usertype) {
		String sql1 = "select password from student where studentid= ?";
		String sql2 = "select password from teacher where teacherid = ?";
		String sql3 = "select password from manager where name= ?";
		String sql  = null;
		Connection conn = DBConn.getConn();
		boolean flag = false;
		
		try{
			if(usertype.equals("3")) sql  = sql3;
			else if(usertype.equals("1")) sql = sql1;
			else sql = sql2;
			PreparedStatement  pstmt = conn.prepareStatement(sql);
			pstmt.setString(1, username);
			ResultSet rs = pstmt.executeQuery();
			if(rs.next()) {
				String password1 = rs.getString(1);
				if(password1.equals(password)) {
					flag = true;
				}
			}
		if(rs!=null) rs.close();
		if(pstmt!=null) pstmt.close();
		}catch(Exception e) {
			e.printStackTrace();
		}
		return flag;
	}
	
	public int ckStu(String studentid)
	{
		int a=0;
		Connection conn = DBConn.getConn();
		try {
			PreparedStatement  stmt = conn.prepareStatement("select count(*) from student where studentid=?");
			stmt.setString(1,studentid);
			ResultSet rs = stmt.executeQuery();
			rs=stmt.executeQuery();
			if(rs.next())
			{
				a=rs.getInt(1);
			}
			
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return a;
	}
	public int ckTea(String teacherid)
	{
		int a=0;
		Connection conn = DBConn.getConn();
		try {
			PreparedStatement  stmt = conn.prepareStatement("select count(*) from teacher where teacherid=?");
			stmt.setString(1,teacherid);
			ResultSet rs = stmt.executeQuery();
			rs=stmt.executeQuery();
			if(rs.next())
			{
				a=rs.getInt(1);
			}
			
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return a;
	}
	
	public void saveStu(String studentid,String password,String name,String sex,String department )
	{
		Connection conn=DBConn.getConn();
		try {
			PreparedStatement stmt=conn.prepareStatement("insert student(studentid,password,name,sex,department)values(?,?,?,?,?)");
			stmt.setString(1,studentid);
			stmt.setString(2,password);
			stmt.setString(3,name);
			stmt.setString(4,sex);
			stmt.setString(5,department);
			stmt.execute();
			
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	public void saveTea(String teacherid,String password,String teachername,String sex,String zhicheng,String department )
	{
		Connection conn=DBConn.getConn();
		try {
			PreparedStatement stmt=conn.prepareStatement("insert teacher(teacherid,password,teachername,sex,zhicheng,department)values(?,?,?,?,?,?)");
			stmt.setString(1,teacherid);
			stmt.setString(2,password);
			stmt.setString(3,teachername);
			stmt.setString(4,sex);
			stmt.setString(5,zhicheng);
			stmt.setString(6,department);
			stmt.execute();
			
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	//修改密码的方法
	public static boolean updatePassword(String username,String oldpassword,String newpassword,String usertype) {
		String sql1 = "update student set password = ? where studentid = ?";
		String sql2 = "update teacher set password = ? where teacherid = ?";
		String sql3 = "update manager set password = ? where name = ?";
		String sql = null;
		Connection conn = DBConn.getConn();
		boolean flag = false;
		
		boolean b = LoginDAO.checkLogin(username, oldpassword, usertype);
		
		if(b){
		try{
				if(usertype.equals("1")) sql = sql1;
				else if(usertype.equals("2")) sql = sql2 ;
				else sql = sql3;
				PreparedStatement pstmt = conn.prepareStatement(sql);
				pstmt.setString(1, newpassword);
				pstmt.setString(2, username);
				System.out.println(sql);
				pstmt.executeUpdate();
				flag = true;
			}catch(Exception e) {
				e.printStackTrace();
			}
		}
		return flag;
	}
}