Tomcat6.0运行时出现 500错误，小弟新手，迷惑中，大虾援助。。。。

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

com.bjsxt.shopping.category.CategoryService.getCategories(CategoryService.java:102) 这行有对象为null

Answer 2

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;
    }