Spring Bean继承和空指针异常问题

时间：2012-10-11 21:23:35

标签： spring javabeans ojb

我正在努力向业务对象添加新bean。

为此，我首先通过为其分配以下内容将成员添加到PurchaseOrderDocument类：

protected String purchaseOrderCurrentCMActionStatus;

然后我当然会给它分配通常的getter和setter，如下所示：

 public String getPurchaseOrderCurrentCMActionStatus() {
    return purchaseOrderCurrentCMActionStatus;
}

public void setPurchaseOrderCurrentCMActionStatus(String purchaseOrderCurrentCMActionStatus) {
    this.purchaseOrderCurrentCMActionStatus = purchaseOrderCurrentCMActionStatus;
}

好的，所以这一切都发生在我的Java类中。

现在，在位于DataDictionary目录中的名为PurchaseOrderDocument.xml的相应XML文件中，我添加了以下bean定义 - 

 <bean id="PurchaseOrderDocument-purchaseOrderCurrentCMActionStatus"
  parent="PurchaseOrderDocument-purchaseOrderCurrentCMActionStatus-parentBean"/>

    <bean id="PurchaseOrderDocument-purchaseOrderCurrentCMActionStatus-parentBean" abstract="true" parent="AttributeDefinition">
    <property name="name" value="purchaseOrderCurrentCMActionStatus"/>
    <property name="label" value="Current CM Action Status"/>
    <property name="required" value="false"/>
    <property name="shortLabel" value="CM Status"/>
    <property name="control">
       <ref bean="HiddenControl"/>
    </property>
 </bean>

接下来，我需要创建OJB映射，因此在ojb.xml文件中我添加了以下XML代码行 - 

<field-descriptor name="purchaseOrderCurrentCMActionStatus" column="CURR_CM_ACTION_STATUS" jdbc-type="VARCHAR"/>

我还在相应的TABLE中创建了CURR_CM_ACTION_STATUS列 - 所以我进行了双倍和三倍检查，这些名称是匹配的一个点。

对 -

所以这是问题所在： 在我的PurchaseOrderDocument中，我有一个触发器，它等待一个事件，该事件将触发我为此bean指定的“Setter”代码。 奇怪的是，我编写的这段代码正在生成一个NULL指针异常。

我已将问题指向以下行 - 

<bean id="PurchaseOrderDocument-purchaseOrderCurrentCMActionStatus-parentBean" abstract="true" parent="AttributeDefinition">

如果我更改以下行：

parent = "AttributeDefinition"

到

parent = "Note-noteText"

（注意是一个Class和noteText是I ORIGINALLY在我继承的这个bean中的成员变量 - 但我不想继承Note类，我希望它在我的PurchaseOrderDocument类本地。无论如何，当我在那里有Note-noteText时，我没有得到空指针异常，而是在我的触发器调用“set”方法之后，NOTHING被写入数据库，顺便说一句是ORACLE。）< / p>

因此，这是我摆脱继承的原因，而我希望这个bean是本类的本地。

我的一位同事提到，也许Spring正在寻找FORM中的这个bean，因为我没有在那里 - 它正在考虑它...但我有疑虑。

另请注意我正在使用隐藏控件。当我添加parent =“AttributeDefinition”文本时，我收到一条错误消息，指出我没有指定控件属性。因为，这个bean的内容不是来自USER输入，所以我指定了这个HIDDEN CONTROL属性。

也许这是问题的一部分??

以下是堆栈跟踪 - 以防万一 - 

Stacktrace:
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:521)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:412)
    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.struts.action.RequestProcessor.doForward(RequestProcessor.java:1085)
    org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:398)
    org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:241)
    org.kuali.rice.kns.web.struts.action.KualiRequestProcessor.process(KualiRequestProcessor.java:101)
    org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
    org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    org.kuali.rice.kew.web.UserLoginFilter.doFilter(UserLoginFilter.java:92)
    org.jasig.cas.client.util.HttpServletRequestWrapperFilter.doFilter(HttpServletRequestWrapperFilter.java:50)
    org.jasig.cas.client.validation.AbstractTicketValidationFilter.doFilter(AbstractTicketValidationFilter.java:167)
    org.jasig.cas.client.authentication.AuthenticationFilter.doFilter(AuthenticationFilter.java:121)
    org.kuali.rice.kns.web.filter.SetResponseBufferSizeFilter.doFilter(SetResponseBufferSizeFilter.java:78)
    org.displaytag.filter.ResponseOverrideFilter.doFilter(ResponseOverrideFilter.java:125)
    org.kuali.rice.kns.web.filter.SessionFilter.doFilter(SessionFilter.java:41)

root cause

javax.servlet.ServletException: javax.servlet.jsp.JspException: java.lang.NullPointerException
    org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:861)
    org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:794)
    org.apache.jsp.jsp.module.purap.PurchaseOrder_jsp._jspService(PurchaseOrder_jsp.java:269)
    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:388)
    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.struts.action.RequestProcessor.doForward(RequestProcessor.java:1085)
    org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:398)
    org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:241)
    org.kuali.rice.kns.web.struts.action.KualiRequestProcessor.process(KualiRequestProcessor.java:101)
    org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
    org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    org.kuali.rice.kew.web.UserLoginFilter.doFilter(UserLoginFilter.java:92)
    org.jasig.cas.client.util.HttpServletRequestWrapperFilter.doFilter(HttpServletRequestWrapperFilter.java:50)
    org.jasig.cas.client.validation.AbstractTicketValidationFilter.doFilter(AbstractTicketValidationFilter.java:167)
    org.jasig.cas.client.authentication.AuthenticationFilter.doFilter(AuthenticationFilter.java:121)
    org.kuali.rice.kns.web.filter.SetResponseBufferSizeFilter.doFilter(SetResponseBufferSizeFilter.java:78)
    org.displaytag.filter.ResponseOverrideFilter.doFilter(ResponseOverrideFilter.java:125)
    org.kuali.rice.kns.web.filter.SessionFilter.doFilter(SessionFilter.java:41)

root cause

java.lang.NullPointerException
    org.kuali.rice.kns.datadictionary.exporter.AttributesMapBuilder.buildAttributeMap(AttributesMapBuilder.java:66)
    org.kuali.rice.kns.datadictionary.exporter.AttributesMapBuilder.buildAttributesMap(AttributesMapBuilder.java:51)
    org.kuali.rice.kns.datadictionary.exporter.DocumentEntryMapper.mapEntry(DocumentEntryMapper.java:88)
    org.kuali.rice.kns.datadictionary.exporter.TransactionalDocumentEntryMapper.mapEntry(TransactionalDocumentEntryMapper.java:30)
    org.kuali.rice.kns.datadictionary.exporter.DataDictionaryMap.get(DataDictionaryMap.java:60)
    javax.el.MapELResolver.getValue(MapELResolver.java:51)
    javax.el.CompositeELResolver.getValue(CompositeELResolver.java:54)
    org.apache.el.parser.AstValue.getValue(AstValue.java:123)
    org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
    org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:938)
    org.apache.jsp.tag.web.kr.documentPage_tag._jspx_meth_c_005fset_005f0(documentPage_tag.java:382)
    org.apache.jsp.tag.web.kr.documentPage_tag.doTag(documentPage_tag.java:313)
    org.apache.jsp.jsp.module.purap.PurchaseOrder_jsp._jspService(PurchaseOrder_jsp.java:260)
    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:388)
    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.struts.action.RequestProcessor.doForward(RequestProcessor.java:1085)
    org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:398)
    org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:241)
    org.kuali.rice.kns.web.struts.action.KualiRequestProcessor.process(KualiRequestProcessor.java:101)
    org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
    org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    org.kuali.rice.kew.web.UserLoginFilter.doFilter(UserLoginFilter.java:92)
    org.jasig.cas.client.util.HttpServletRequestWrapperFilter.doFilter(HttpServletRequestWrapperFilter.java:50)
    org.jasig.cas.client.validation.AbstractTicketValidationFilter.doFilter(AbstractTicketValidationFilter.java:167)
    org.jasig.cas.client.authentication.AuthenticationFilter.doFilter(AuthenticationFilter.java:121)
    org.kuali.rice.kns.web.filter.SetResponseBufferSizeFilter.doFilter(SetResponseBufferSizeFilter.java:78)
    org.displaytag.filter.ResponseOverrideFilter.doFilter(ResponseOverrideFilter.java:125)
    org.kuali.rice.kns.web.filter.SessionFilter.doFilter(SessionFilter.java:41)

1 个答案:

答案 0 :(得分：1)

结果证明上述代码是正确的。

这个问题是我在一个瞬态对象上调用我的setter方法，该方法没有被Spring Framework持久化。 （例如，我在一个对象上调用它，其范围在我调用它的块中结束！）

为了解决这个问题，我只是在另一个范围内的同一个实例上调用了setter。

... Ughh

生活和学习。

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