java dispatcher.forward抛出空异常
我犯了以下错误java dispatcher.forward抛出空异常,java,eclipse,jsp,servlets,requestdispatcher,Java,Eclipse,Jsp,Servlets,Requestdispatcher,我犯了以下错误 HTTP Status 500 - 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.a
HTTP Status 500 -
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:548)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:471)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
ahp.CompareCriterionSlider.doGet(CompareCriterionSlider.java:35)
javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
root cause
java.lang.NullPointerException
org.apache.jsp.CompareCriterionSlider_jsp._jspService(CompareCriterionSlider_jsp.java:91)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:433)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
ahp.CompareCriterionSlider.doGet(CompareCriterionSlider.java:35)
javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
对于线路:dispatcher.forward(请求、响应)代码>
我在目录WebContent/
我试图设置断点来调试它,但eclipse(版本:Indigo Service Release 2)给了我:找不到源代码。
投票否决我的人是否愿意给出原因?JSP抛出了一个空指针异常,您需要在JSP中找到导致该异常的确切代码行
一种方法是简单地打开jsp的编译java文件,即CompareCriterionSlider_jsp.java:91,然后将其映射到jsp中的行。
一旦你这样做了,如果它是一个空指针,那么就可以直接计算出错误。
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
HttpSession session = request.getSession(true);
session.setAttribute("criterions", CriterionRecommander.values() );
RequestDispatcher dispatcher = getServletContext().getRequestDispatcher("/CompareCriterionSlider.jsp");
dispatcher.forward(request, response);
}