我使用JSF复合组件来重用组件。然而，我一直得到一个空指针错误，我遵循一些教程，我发现，但没有提到这个问题。
堆栈跟踪添加:
java.lang.NullPointerException
at com.sun.faces.application.view.FaceletViewHandlingStrategy$MethodRetargetHandlerManager$ArbitraryMethodRegargetHandler.retarget(FaceletViewHandlingStrategy.java:1883)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.retargetMethodExpressions(FaceletViewHandlingStrategy.java:772)
at com.sun.faces.facelets.tag.jsf.CompositeComponentTagHandler.applyNextHandler(CompositeComponentTagHandler.java:201)
at com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:190)
at javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120)
at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:95)
at javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:137)
at com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:190)
at javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120)
at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:95)
at com.sun.faces.facelets.compiler.NamespaceHandler.apply(NamespaceHandler.java:93)
at com.sun.faces.facelets.compiler.EncodingHandler.apply(EncodingHandler.java:87)
at com.sun.faces.facelets.impl.DefaultFacelet.apply(DefaultFacelet.java:161)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.buildView(FaceletViewHandlingStrategy.java:972)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:99)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:357)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:260)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:188)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
at java.lang.Thread.run(Thread.java:745)
我使用的是Netbean 8.0, JSF包含在企业应用程序项目中，不确定这是否与webApplication项目有任何区别。
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://xmlns.jcp.org/jsf/html"
xmlns:composite="http://xmlns.jcp.org/jsf/composite"
xmlns:f="http://xmlns.jcp.org/jsf/core">
<h:head>
</h:head>
<h:body>
<composite:interface>
<composite:attribute name="action"/>
</composite:interface>
<composite:implementation>
<h:form>
<h:panelGrid columns="2">
<h:panelGroup>Customer Name:</h:panelGroup>
<h:panelGroup>
<h:inputText value="#{MyMB.customer.name}">
<f:validateRegex pattern="(?:[A-Za-z]+s*)+"/>
</h:inputText>
</h:panelGroup>
<h:panelGroup>Address:</h:panelGroup>
<h:panelGroup>
<h:inputText value="#{MyMB.customer.address}"></h:inputText>
</h:panelGroup>
<h:panelGroup>Date Of Birth:</h:panelGroup>
<h:panelGroup>
<h:inputText value="#{MyMB.customer.dateOfBirth}">
<f:convertDateTime pattern="MM/dd/yyyy"/>
</h:inputText>
</h:panelGroup>
<h:panelGroup>Gender:</h:panelGroup>
<h:panelGroup>
<h:selectOneRadio value="#{MyMB.customer.gender}">
<f:selectItem itemValue="Male" itemLabel="Male"/>
<f:selectItem itemValue="Female" itemLabel="Female"/>
</h:selectOneRadio>
</h:panelGroup>
</h:panelGrid>
<h:commandButton value="Submit" action="#{cc.attrs.action}"></h:commandButton>
</h:form>
</composite:implementation>
</h:body>
</html>
Index.xhtml
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://xmlns.jcp.org/jsf/html"
xmlns:f="http://xmlns.jcp.org/jsf/core"
xmlns:comp="http://java.sun.com/jsf/composite/comp">
<h:head>
<title>Customers Management</title>
</h:head>
<h:body>
<h:button value="Register Customer" outcome="register.xhtml"></h:button>
<h:button value="Update Customer Info" outcome="update.xhtml"></h:button>
<comp:customerForm action="#{MyMB.findCustomer()}"></comp:customerForm>
<h:panelGrid columns="2">
<h:panelGroup>
</h:panelGroup>
<h:panelGroup>
<h:form>
<h:selectOneListbox style="margin-left: 100px; width:200px; height:120px" value="#{MyMB.customer}">
<f:selectItems value="#{MyMB.listOfCust}"/>
</h:selectOneListbox>
<h:commandButton value="Remove" action="#{MyMB.removeCustomer()}"></h:commandButton>
<h:commandButton value="Update Customer Info" action="update.xhtml"></h:commandButton>
</h:form>
</h:panelGroup>
</h:panelGrid>
</h:body>
</html>
试试这个
<composite:attribute name="action" method-signature="java.lang.String action()"/>