java.lang.NullPointerExceptioncom.yxq.dao.LogonDao.logon(LogonDao.java:49)com.yxq.servlet.LogXServlet.logon(LogXServlet.java:71)com.yxq.servlet.LogXServlet.doPost(LogXServlet.java:29)javax.servlet.http.HttpServlet.service(HttpServlet.java:637)ja

Question

java.lang.NullPointerException
com.yxq.dao.LogonDao.logon(LogonDao.java:49)
com.yxq.servlet.LogXServlet.logon(LogXServlet.java:71)
com.yxq.servlet.LogXServlet.doPost(LogXServlet.java:29)
javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

Answer 1

空指针,LogonDao.logon 到这个方法里面看看对象,变量是不是都初始化了,
49：rs.close();
rs有没有打开?加个判断试下
if(rs!=null){
rs.close();
}