tomcat6.0 运行jsp时出现500错误提示，急急急急急

Question

type Exception reportmessage 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:522)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:416)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
com.bjsxt.shopping.util.filter.IPFilter.doFilter(IPFilter.java:31)
root cause java.lang.NullPointerException
com.bjsxt.shopping.category.CategoryService.getCategories(CategoryService.java:102)
org.apache.jsp.Index_jsp._jspService(Index_jsp.java:95)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
com.bjsxt.shopping.util.filter.IPFilter.doFilter(IPFilter.java:31)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.18 logs.

Answer 1

同时发两个相同的帖子？com.bjsxt.shopping.category.CategoryService.getCategories(CategoryService.java:102) 这个类是你写的吧，检查一下，在调用之前检查一下对象是不是null 

Answer 2

com.bjsxt.shopping.category.CategoryService.getCategories(CategoryService.java:102) 
找到这行看看什么为null、

Answer 3

不是运行JSP问题，CategoryService类102行调用getCategories的实例为空。测试下

Answer 4

空指针异常,检查com.bjsxt.shopping.category.CategoryService.getCategories(CategoryService.java:102) CategoryService这个类

Answer 5

root cause java.lang.NullPointerException 
com.bjsxt.shopping.category.CategoryService.getCategories(CategoryService.java:102) 注意一下之前的是否有空的实例

Answer 6

bjsxt,呵呵,我也看过他的教程,感觉不错~~
java.lang.NullPointerException 
com.bjsxt.shopping.category.CategoryService.getCategories(CategoryService.java:102) 
空指针错误,
看看数据库连接是不是有问题,看看下面两处关键的地方是不是有问题:
Category c = this.getCategoryFromRs(rs);private Category getCategoryFromRs(ResultSet rs) {
Category c = new Category();
try {
c.setId(rs.getInt("id"));
c.setPid(rs.getInt("pid"));
c.setName(rs.getString("name"));
c.setDescr(rs.getString("descr"));
c.setCno(rs.getInt("cno"));
c.setGrade(rs.getInt("grade"));
} catch (SQLException e) {
e.printStackTrace();
}
return c;
}

Answer 7

com.bjsxt.shopping.category.CategoryService.getCategories(CategoryService.java:102) 
如果102行是
Category c = this.getCategoryFromRs(rs);估计 this为NULL

Answer 8

org.apache.jasper.JasperException: java.lang.NullPointerException 空指针错误，
楼主的这个类好像有错误com.bjsxt.shopping.util.filter.IPFilter.doFilter(IPFilter.java:31) 
有没有返回值，或其返回值为null