在jsp中从数据库中读取数据出现空指针异常

sql="select*from车辆where车辆编号='"+trainnumber+"'";rs=dodata.executeQuery(sql);if(rs!=nul... sql="select * from 车辆 where 车辆编号='"+trainnumber+"'";
rs=dodata.executeQuery(sql);
if(rs!=null&&rs.next()){
trainnumber=rs.getString(1);
traintype=rs.getString(2);
boxnum=rs.getInt(3);
platformnum=rs.getInt(4);
session.setAttribute("trainnumber", trainnumber);
session.setAttribute("traintype", traintype);
session.setAttribute("boxnum", boxnum);
session.setAttribute("platformnum",platformnum);
}else{
response.sendError(443, "查询站台出错！");
}
rs.close();
dodata.close();
//查询车厢信息
int i=0;
dodata.open();
sql2="select * from 车厢 where 车辆编号='"+trainnumber+"'";
rs2=dodata.executeQuery(sql2);
while(rs2!=null&&rs2.next()){
boxname[i]=rs2.getInt("车厢号")+"号车厢";
boxtype[i]=rs2.getString("类型");
seatnum[i]=rs2.getInt("座位数");
i++;
}
session.setAttribute("boxnameArray",boxname);
session.setAttribute("boxtypeArray",boxtype);
session.setAttribute("seatnumArray",seatnum);
rs2.close();
dodata.close();
//查询车次信息
i=0;
dodata.open();
sql3="select 车次.车次,始发站,出发时刻,车站名,里程,到达时刻,发出时刻,停留时间,无座票价,硬座票价,硬卧票价,软座票价,软卧票价 from 车次,经过站 where 车次.车次=经过站.车次 and 车辆编号='"+trainnumber+"'";
rs3=dodata.executeQuery(sql3);
if(rs3!=null&&rs3.next()){
trainnum=rs3.getString(1);
startstation=rs3.getString(2);
starttime=rs3.getString(3);
platname[i]=rs3.getString(4);
journey[i]=rs3.getFloat(5);
reachtime[i]=rs3.getString(6);
leavetime[i]=rs3.getString(7);
staytime[i]=rs3.getString(8);
noseat[i]=rs3.getFloat(9);
hseat[i]=rs3.getFloat(10);
hbed[i]=rs3.getFloat(11);
sseat[i]=rs3.getFloat(12);
sbed[i]=rs3.getFloat(13);
}
while(rs3!=null&&rs3.next()){
i++;
platname[i]=rs3.getString(4);
journey[i]=rs3.getFloat(5);
reachtime[i]=rs3.getString(6);
leavetime[i]=rs3.getString(7);
staytime[i]=rs3.getString(8);
noseat[i]=rs3.getFloat(9);
hseat[i]=rs3.getFloat(10);
hbed[i]=rs3.getFloat(11);
sseat[i]=rs3.getFloat(12);
sbed[i]=rs3.getFloat(13);
}
HttpSession session=request.getSession();
response.setContentType("text/html; charset=gb2312");
String trainnumber=request.getParameter("trainID");
ResultSet rs=null,rs2=null,rs3=null;
String sql=null,sql2=null,sql3=null;
String trainnum=null,traintype=null,startstation=null,starttime=null;
String[] boxname = null;
String[] boxtype=null;
int[] seatnum = null;
int platformnum=0,boxnum=0;
String[] platname=null,reachtime=null,leavetime=null,staytime=null;
float[] journey = null,noseat = null,hseat = null,hbed = null,sseat = null,sbed = null; 展开

 我来答