为什么我在 liferay 中收到 NullPointerException？

我得到了NullPointerException在下面一行：

originalStrutsPortletAction.processAction(
                    originalStrutsPortletAction, portletConfig, actionRequest,
                        actionResponse);

我正在打印所有值：

System.out.println(originalStrutsPortletAction);
System.out.println(portletConfig);
System.out.println(actionRequest);
System.out.println(actionResponse);

Output:

com.liferay.portal.struts.StrutsPortletActionAdapter@2f20c4be
com.liferay.portlet.PortletConfigImpl@5f4268dd
com.liferay.portlet.ActionRequestImpl@1054ae1e
com.liferay.portlet.ActionResponseImpl@27733bf2

那么为什么我会得到NullPointerException？请帮忙。提前致谢。 完整的堆栈跟踪如下：-

java.lang.NullPointerException
    at com.liferay.portlet.login.action.LoginAction.login(LoginAction.java:196)
    at com.liferay.portlet.login.action.LoginAction.processAction(LoginAction.java:93)
    at com.liferay.portal.struts.StrutsPortletActionAdapter.processAction(StrutsPortletActionAdapter.java:60)
    at com.liferay.portal.kernel.struts.BaseStrutsPortletAction.processAction(BaseStrutsPortletAction.java:44)
    at com.abhishek.ExampleLoginAction.check(ExampleLoginAction.java:185)
    at org.apache.jsp.jsp.otpCheck_jsp._jspService(otpCheck_jsp.java:71)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
    at sun.reflect.GeneratedMethodAccessor503.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.liferay.portal.kernel.bean.ClassLoaderBeanHandler.invoke(ClassLoaderBeanHandler.java:67)
    at com.sun.proxy.$Proxy660.doFilter(Unknown Source)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:165)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:96)
    at com.liferay.portal.kernel.servlet.PortalClassLoaderFilter.doFilter(PortalClassLoaderFilter.java:74)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:204)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:109)
    at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:96)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

简单的答案：您在该位置没有得到 NullpointerException - 至少根据您发布的堆栈跟踪没有得到。 Liferay 的LoginAction 没有originalStrutsAction。如果您使用的是 6.2 GA5，这是代码 https://github.com/liferay/liferay-portal/blob/6.2.x/portal-impl/src/com/liferay/portlet/login/action/LoginAction.java#L196抛出 NullpointerException。为什么？那不是你问的。

或者，换句话说：您将收到 NullpointerException，因为您取消引用 Nullpointer。您只需要确定您实际从哪里获得它。堆栈跟踪有帮助。谁知道您的 ExampleLoginAction 在调用您要发布的行之前会做什么...