org.apache.jasper.JasperException: java.lang.NullPointerException
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:541)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:435)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
root cause java.lang.NullPointerException
org.apache.jsp.ver_jsp._jspService(ver_jsp.java:71)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
上面是出错代码,想问下是在哪出错了。
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:541)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:435)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
root cause java.lang.NullPointerException
org.apache.jsp.ver_jsp._jspService(ver_jsp.java:71)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
上面是出错代码,想问下是在哪出错了。
你找找哪有这空指针错误。如果实在找不出你就找出ver_jsp.java:71这行来看下到底哪出错。
<jsp:useBean id="conn" class="dbBean.DBBean" scope="session"/>
<%
String user=request.getParameter("user");
String pw=request.getParameter("pw");
String sql="select * from login where name='"+user+"' and password='"+pw+"'";
ResultSet rs=conn.executeQuery(sql);
if(rs.next())
{
rs.close();
conn.close();
session.setAttribute("login","ok");
%>
<jsp:forward page="add.jsp"/>
<%
}
else
{
rs.close();
conn.close();
%>
<jsp:forward page="loginhui.jsp">
<jsp:param name="warning" value=""/>
</jsp:forward>
<%
}
%>
或者你看看rs里有值么
user="";
if(pw==null)
pw="";
捕捉空指针:
System.out.println(user.length());
System.out.println(pw.length());
如果Tomcat服务器输出的是00的话就是你的user 和pw 为空所致
还要检查你的登录页面的关键子和user pw 是否一致
根本原因,明显是你代码写得有问题。debug看看。
String pw=request.getParameter("pw"); 没有取到值
String pw=request.getParameter("pw"); 可能没有取到值,
你把你这两个值一个一个的赋初值测试就知道那个包空指针异常了。