org.apache.catalina.core.ApplicationDispatcher 调用引发异常 java.lang.NullPointerException

问：

使用 Eclipse 进行 MVC，

1. 如果以 开头，则列表效果很好。com.controller.main/mainServlet.java
2. 但是如果从 、 到 开始，则会出现此错误。WebContect/main.jspWebcontent/goods/goodsList.jsp

在 Servlet 中，任一

请求调度程序 dis = request.getRequestDispatcher（“main.jsp”）;

或

RequestDispatcher dis = request.getRequestDispatcher（“goods/goodsList.jsp”）;，

无论如何，如果在 main.jsp 中启动，则会出现错误。

java.lang.NullPointerException
    at org.apache.jsp.goods.goodsList_jsp._jspService(goodsList_jsp.java:139)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:71)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:476)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:386)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:330)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:713)
    at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:583)
    at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:519)
    at org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:865)
    at org.apache.jsp.main_jsp._jspService(main_jsp.java:137)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:71)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:476)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:386)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:330)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:543)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:690)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:615)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:818)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1626)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)

at org.apache.jsp.goods.goodsList_jsp._jspService(goodsList_jsp.java:139)

这部分就在这里。我真的很想知道......

<%
    List<GoodsDTO> list = (List<GoodsDTO>)request.getAttribute("goodsList");
    for( int i = 1; i <=  list.size(); i++ ){
        GoodsDTO dto = list.get(i+1);
        String gCode = dto.getgCode();
        String gCategory = dto.getgCategory();
        String gName = dto.getgName();
        String gContent = dto.getgContent();
        int gPrice = dto.getgPrice();
        String gImage = dto.getgImage();
%>