carddao.java

我做的第一个java MIS项目

package server.dao;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Connection;
import server.entity.User;
import java.sql.SQLException;
import server.entity.Card;
import server.entity.Sysconfig;

public class Carddao {

    private Connection con = null;
    private Connectionmanager cm=null;
    private PreparedStatement ps = null;
    private ResultSet rs = null;

    //检验客户有效性
    public boolean chkcard(Card card)
    {
        //初始化变量
        String testcardid=card.getcardid();
        String testcardpwd=card.getcardpwd();
        String realcardpwd="";
        String dbcardid=null;
        String dbcardpwd=null;
        //创建一个连接并得到查询结果
        cm =new Connectionmanager();
        con= cm.getconnection();
        try
        {
            ps = con.prepareStatement("select cardpwd from card where cardid='" +testcardid+ "'");
            rs=ps.executeQuery();
            rs.next();
            realcardpwd=rs.getString(1);
        }
        catch (SQLException ex) {return false;}
        //断开数据连接
        finally
        {
            cm.closeresultset(rs);
            cm.closestatement(ps);
            cm.closeconnection(con);
        }

        //判断并返回判断值
        if (realcardpwd.equals(testcardpwd))
        {return true;}
        else
        {return false;}
    }

    //检查客户帐户借出数量是否达到上限
    public boolean chkcdoutnum(Card cardtemp)
    {
        //初始化变量
        String testcardid=cardtemp.getcardid();
        int testcdoutnum=0;

        //创建一个连接并得到查询结果
        cm =new Connectionmanager();
        con= cm.getconnection();
        try
        {
            ps = con.prepareStatement("select count(*) from record where reccardid='"+testcardid+"' and recendtime='1970-01-01'");
            rs=ps.executeQuery();
            rs.next();
            testcdoutnum=rs.getInt(1);
        }
        catch (SQLException ex) {return false;}
        //断开数据连接
        finally
        {
           cm.closeresultset(rs);
           cm.closestatement(ps);
           cm.closeconnection(con);
        }

        //判断并返回判断值
        if (testcdoutnum<=Sysconfig.getcdoutmaxnum())
        {return true;}
        else
        {return false;}
    }

    //检查客户帐户是否还可以借阅
    public boolean chkcdrestnum(Card cardtemp)
    {
        //初始化变量
        String testcardid=cardtemp.getcardid();
        int testcardrestnum=0;

        //创建一个连接并得到查询结果
        cm =new Connectionmanager();
        con= cm.getconnection();
        try
        {
            ps = con.prepareStatement("select cardrestnum from card where cardid='" +testcardid+ "'");
            rs=ps.executeQuery();
            rs.next();
            testcardrestnum=rs.getInt(1);
        }
        catch (SQLException ex) {return false;}
        //断开数据连接
        finally
        {
           cm.closeresultset(rs);
           cm.closestatement(ps);
           cm.closeconnection(con);
        }

        //判断并返回判断值
        if (testcardrestnum>0)
        {return true;}
        else
        {return false;}
    }

    //得到最大卡号
    public int getmaxcardid()
    {
        //初始化变量
        int maxcardid=0;
        int t=0;

        //创建一个连接并得到查询结果
        cm =new Connectionmanager();
        con= cm.getconnection();
        try
        {
            ps = con.prepareStatement("select cardid from card");
            rs = ps.executeQuery();
            while (rs.next())
            {
                t=rs.getInt(1);
                if (maxcardid<t)
                {maxcardid=t;}
            }
        }
        catch (SQLException ex) {}
        //断开数据连接
        finally
        {
            cm.closeresultset(rs);
            cm.closestatement(ps);
            cm.closeconnection(con);
        }
        //返回值
        {return maxcardid;}
    }

}