Java 处理onSubmitation后引发异常

我对Spring非常陌生，我有一个simpleFormController，有两种方法。页面加载时调用referenceData with，提交表单时调用Submitation。在所有onsubmition代码完成之后，我得到了一个NullPointerException，我怀疑这与方法完成后控制流的去向有关。我希望在submitAction之后调用referenceData，以便页面的行为与首次加载时相同

<bean id="communicationsValidator" class="com.admin.portlet.communication.CommunicationsValidator"/>

<bean id="communicationsController" class="com.admin.portlet.communication.CommunicationsAdminController">
    <property name="commandName" value="communications"/>
    <property name="commandClass" value="com.admin.portlet.communication.vo.Communication"/>
    <property name="formView" value="communications/communicationsAdmin"/>
    <property name="successView" value="communications/communicationsAdmin"/>
    <property name="validator"><ref bean="communicationsValidator"/></property>
    <property name="dao"><ref bean="communicationsDao"/></property>
</bean>

<bean id="portletModeHandlerMapping" class="org.springframework.web.portlet.handler.PortletModeHandlerMapping">
    <property name="order" value="1"/>
    <property name="portletModeMap">
        <map>
            <entry key="view"><ref bean="communicationsController"/></entry>
        </map>
    </property>
</bean>

我还有一个要求，可能会改变我上面的想法。我想根据onsubmition的结果传回一条成功或错误消息。最好的方法是什么。以下是我的代码的相关部分：

protected Map referenceData(PortletRequest arg0, Object arg1, Errors arg2) throws Exception 
    {
        Map<String, Object> model = new HashMap<String, Object>();

            List<Communication> allCommunications = dao.getAllCommunications();
            model.put("allCommunications", allCommunications);
            model.put("error", "");   //not sure how to get this data
            model.put("success", ""); //not sure how to get this data

        return model;
    }

protected void onSubmitAction(ActionRequest argRequest,
        ActionResponse argResponse, Object command, BindException errors)
        throws Exception
{
    Communication form = (Communication) command;

        dao.updateCommunication(form);
        //I want to set a success message here that can be read in the JSP

<bean id="communicationsValidator" class="com.admin.portlet.communication.CommunicationsValidator"/>

<bean id="communicationsController" class="com.admin.portlet.communication.CommunicationsAdminController">
    <property name="commandName" value="communications"/>
    <property name="commandClass" value="com.admin.portlet.communication.vo.Communication"/>
    <property name="formView" value="communications/communicationsAdmin"/>
    <property name="successView" value="communications/communicationsAdmin"/>
    <property name="validator"><ref bean="communicationsValidator"/></property>
    <property name="dao"><ref bean="communicationsDao"/></property>
</bean>

<bean id="portletModeHandlerMapping" class="org.springframework.web.portlet.handler.PortletModeHandlerMapping">
    <property name="order" value="1"/>
    <property name="portletModeMap">
        <map>
            <entry key="view"><ref bean="communicationsController"/></entry>
        </map>
    </property>
</bean>

JSP内部产生的异常很难调试，特别是在JSP中根本不使用Scriptlet的情况下。这将表明所使用的标记库中有一个bug，或者业务逻辑中有一个微不足道的配置/流错误，这在后期揭示了这个异常

<bean id="communicationsValidator" class="com.admin.portlet.communication.CommunicationsValidator"/>

<bean id="communicationsController" class="com.admin.portlet.communication.CommunicationsAdminController">
    <property name="commandName" value="communications"/>
    <property name="commandClass" value="com.admin.portlet.communication.vo.Communication"/>
    <property name="formView" value="communications/communicationsAdmin"/>
    <property name="successView" value="communications/communicationsAdmin"/>
    <property name="validator"><ref bean="communicationsValidator"/></property>
    <property name="dao"><ref bean="communicationsDao"/></property>
</bean>

<bean id="portletModeHandlerMapping" class="org.springframework.web.portlet.handler.PortletModeHandlerMapping">
    <property name="order" value="1"/>
    <property name="portletModeMap">
        <map>
            <entry key="view"><ref bean="communicationsController"/></entry>
        </map>
    </property>
</bean>

---

首先，在appserver的工作目录中找到_communicationsAdmin.java文件，并调查第212行是否存在潜在的空指针，最终将其追溯到潜在的配置/流错误。如果您在调试过程中遇到困难，您也可以在此处仅粘贴相关的“是”行，以便我们可以为您定位。

发布堆栈跟踪会很有帮助。感谢您的建议，我现在已经添加了它。感谢您的回复。我不确定为什么要加载jsp。我希望在请求返回到浏览器之前调用referenceData方法？我甚至不知道这是否有意义，但我需要获取一个对象列表，并以与初始加载页面时相同的方式返回它们。此外，我不知道在哪里可以找到JSP的.java版本？我正在搜索我的硬盘，但似乎什么也没找到

<bean id="communicationsValidator" class="com.admin.portlet.communication.CommunicationsValidator"/>

<bean id="communicationsController" class="com.admin.portlet.communication.CommunicationsAdminController">
    <property name="commandName" value="communications"/>
    <property name="commandClass" value="com.admin.portlet.communication.vo.Communication"/>
    <property name="formView" value="communications/communicationsAdmin"/>
    <property name="successView" value="communications/communicationsAdmin"/>
    <property name="validator"><ref bean="communicationsValidator"/></property>
    <property name="dao"><ref bean="communicationsDao"/></property>
</bean>

<bean id="portletModeHandlerMapping" class="org.springframework.web.portlet.handler.PortletModeHandlerMapping">
    <property name="order" value="1"/>
    <property name="portletModeMap">
        <map>
            <entry key="view"><ref bean="communicationsController"/></entry>
        </map>
    </property>
</bean>