网站空指针异常怎么解决！！！

前提，数据库是同一个网络数据库，
本地访问时，一切正常，当用域名访问时有些功能报出空指针，错误信息如下org.apache.jasper.JasperException: An exception occurred processing JSP page /product.jsp at line 8885:       <a href="javascript:void(0);"><%=productTable.getName() %></a><br />
86:  <%
87:  }else{
88:  for(int i=0; i<list.size(); i++){
89:  productTable = (ProductTable)list.get(0);
90:  %>
91:   <a href="javascript:void(0);"><%=productTable.getName() %></a><br />
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:519)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:428)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)java.lang.NullPointerException
org.apache.jsp.product_jsp._jspService(product_jsp.java:171)
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:386)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
org.apache.struts2.dispatcher.ServletDispatcherResult.doExecute(ServletDispatcherResult.java:154)
org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:186)
com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:362)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:266)
com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252)我知道这是空指针异常，请不要告诉我这个是空指针异常，我知道list是一个NULL对象，
我是问，为什么本地没问题，用域名就出问题，谢谢诸位大神了。