JSP运行不了，请高手看看怎么弄

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

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)
ata.wx.shopping.filter.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:124)

root cause

java.lang.NullPointerException
ata.wx.shopping.dao.impl.ProductDAOImpl.selectAll(ProductDAOImpl.java:185)
org.apache.jsp.index_jsp._jspService(index_jsp.java:295)
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)
ata.wx.shopping.filter.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:124)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.13 logs.

这里是空指针问题，看一下JspServletWrapper.java这个文件下的541行的变量是不是null，可以加上if判断如果不为空，再执行该语句。

java.lang.NullPointerException
ata.wx.shopping.dao.impl.ProductDAOImpl.selectAll(ProductDAOImpl.java:185)
ProductDAOImpl这个里面的selectAll()方法报空了