计算机192-25.zip

package dao; import model.User; import utils.DbUtils; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; public class UserDao { //根据用户名密码，判断数据库中是否存在该记录 //输入用户名，密码 //输出： public User selectUserByNameAndPwd(String userName,String userPassword){ ResultSet resultSet = DbUtils.exeQuery( "select * from user where userName=? and userPassword=?" ,userName,userPassword); try { if (resultSet.next()){ User user = new User(resultSet.getInt(1), resultSet.getString(2), resultSet.getString(3)); return user; } }catch (SQLException throwables){ throwables.printStackTrace(); }finally { DbUtils.closeConnection(); } return null; } public int insert(User user){ String sql = "insert into user values(?,?,?) "; return DbUtils.exeUpdate(sql,user.getUserId(),user.getUsername(),user.getPassword()); } public int delete(int userId) { String sql = "delete from user where userId=?"; return DbUtils.exeUpdate(sql, userId); } public int update(User user) { String sql = "update user set userName=?,userPassword=? where userId=?"; return DbUtils.exeUpdate(sql,user.getUsername(),user.getPassword(),user.getUserId()); } public User selectById(int userId) { String sql = "select * from user where userId = ?"; ResultSet resultSet = DbUtils.exeQuery(sql,userId); List<User> list = new ArrayList<>(); try { if(resultSet.next()){ return new User( resultSet.getInt(1), resultSet.getString(2), resultSet.getString(3) ); } }catch (SQLException throwable){ throwable.printStackTrace(); }finally { DbUtils.closeConnection(); } return null; } public List<User> queryALL() { String sql = "select * from user"; ResultSet resultSet = DbUtils.exeQuery(sql); List<User> list = new ArrayList<>(); try { while (resultSet.next()){ User user = new User( resultSet.getInt(1), resultSet.getString(2), resultSet.getString(3) ); list.add(user); } }catch (SQLException throwables){ throwables.printStackTrace(); }finally { DbUtils.closeConnection(); } return list; } public Object selectByName() { String sql = "select * from user where userName = ?"; ResultSet resultSet = DbUtils.exeQuery(sql); List<User> list = new ArrayList<>(); try { if(resultSet.next()){ User user = new User(resultSet.getInt(1), resultSet.getString(2), resultSet.getString(3)); list.add(user); } }catch (SQLException throwables){ throwables.printStackTrace(); }finally { DbUtils.closeConnection(); } return list; } }