calldao.java

火车订票。。 只有部分代码。实现功能是基本的查询和订购功能

package trainticket.Dao;
import java.sql.*;
import trainticket.Bean.*;
/**
  数据库访问层
 */
public class CallDao
{
     DBCOnn dbConn;
       public CallDao()
     {
         dbConn=new DBCOnn();
        try {
            jbInit();
        } catch (Exception ex) {
            ex.printStackTrace();
        }

    }
      public boolean SelectTrainOrder(String trainNum)//检查车次是否在数据库中存在
      {   Connection conn=null;
            try {
            conn=this.dbConn.getConn();
            PreparedStatement ptrt = conn.prepareStatement(
                    "select TrainNo from TrainTicket where TrainNo=?");
            ptrt.setString(1,trainNum);
            ResultSet res=ptrt.executeQuery();
            if(res.next())
            {
                return true;
            }
        } catch (SQLException ex)
        {
            ex.printStackTrace();
        }  finally
      {
            try {
                dbConn.CloseConn(conn);
            } catch (SQLException ex1)
            {
                 ex1.printStackTrace();
            }
      }
            return false;
      }

      public String compareAmount(Info info)//检测订购数量
      {
          PreparedStatement ptrt=null;
          Connection conn=null;
          try {
              conn=this.dbConn.getConn();
              if(info.getPrice().equals("seatPrice"))//坐
              {

                    ptrt = conn.prepareStatement(
                    "select seatNum,seatPrice from TrainTicket where TrainNo=?");
              }
              else //床
              {
                  ptrt = conn.prepareStatement(
                    "select bedNum,bedPrice from TrainTicket where TrainNo=?");
              }
            ptrt.setString(1,info.getTrainNumber());//设置车次
            ResultSet res=ptrt.executeQuery();//执行
            while(res.next())
            {
                  if(res.getInt(1)<info.getNumber())//判断数据库的数量是否小于订购的数量
                  {
                      return "Sorry,订购失败，车票数量不足";
                  }
                  else
                  {
                      return "车票订购成功，请支付："+(new Float(info.getNumber()*res.getFloat(2)).toString())+"元";
                  }

            }
        } catch (SQLException ex)
        {
            ex.printStackTrace();
        }
        finally
      {
            try {
                dbConn.CloseConn(conn);
            } catch (SQLException ex1)
            {
                 ex1.printStackTrace();
            }
      }

            return "";

      }

    private void jbInit() throws Exception {
    }


}