Question

这是我的Java代码：

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@page import="java.util.*" %>
<%!
String fName = "";
String lName = "";
String gender = "";
String uOutput = "";
String uOutput2 = "";
String uOutput3 = "";
%>
<%
int i;
Cookie[] cookies = request.getCookies();
for (i=0; i < cookies.length; i++){
    if (cookies[i].getName().equals("firstname")){
        fName = cookies[i].getValue();
    }
}

if (!fName.equals("")){
    uOutput = "Hello " + fName;
}else{
    fName = request.getParameter("fName");
    lName = request.getParameter("lName");
    gender = request.getParameter("gender");
    if (gender == null){
        response.sendRedirect("form.html");
    }else if(gender.equals("Male")){
        uOutput = "Hello mr " + lName;
    }else if (gender.equals("Female")){
        uOutput = "Hello miss " + lName;
    }

    uOutput2 = "May i call you "+fName+" ?";
    uOutput3 = "<input type='submit' name='YES' value='YES' /><input type='submit' name='NO' value='NO' />";

    if (request.getParameter("YES")!=null){
        Cookie firstname = new Cookie("firstname",fName);
        Cookie lastname = new Cookie("lastname",lName);
        Cookie ugender = new Cookie("gender",gender);
        response.addCookie(firstname);
        response.addCookie(lastname);
        response.addCookie(ugender);
    }

    if (request.getParameter("NO")!=null){

    }
}
%>

这是HTML：

<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>JSP Page</title>
</head>
<body>
    <form method="POST" action="welcome.jsp?fName=<%=fName%>&lName=<%=lName%>&gender=<%=gender%>">
    <h1><%= uOutput %></h1>
    <h2><%= uOutput2 %></h2>
    <%= uOutput3 %>
    </form>
</body>
</html>

浏览器给出Glassfish服务器500内部错误，我找不到错误，我尝试了所有的东西，但它似乎没有帮助，有时其工作正常的奇怪的事情。

这是错误：

例外

org.apache.jasper.JasperException：java.lang.NullPointerException

根本原因

显示java.lang.NullPointerException

任何人都可以帮忙吗？

完整的堆栈跟踪：

    Warning:   StandardWrapperValve[jsp]: Servlet.service() for servlet jsp threw exception
    java.lang.NullPointerException
            at org.apache.jsp.welcome_jsp._jspService(welcome_jsp.java:58)
            at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:111)
            at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
            at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:411)
            at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:473)
            at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:377)
            at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
            at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
            at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
            at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
            at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
            at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
            at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
            at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
            at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:415)
            at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:282)
            at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459)
            at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167)
            at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:201)
            at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:175)
            at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235)
            at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
            at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:284)
            at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:201)
            at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:133)
            at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:112)
            at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
            at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:561)
            at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112)
            at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117)
            at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56)
            at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137)
            at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:565)
            at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:545)
            at java.lang.Thread.run(Thread.java:745)

JSP和Glassfish服务器500内部错误（java.lang.NullPointerException）

0 个答案: