我是否可以递归地将复合组件嵌套在其自身中？

问题描述 投票：0回答：2

我有包含其自身的DTO（已嵌套）。

public class MyDTO {

   private SomeData someData;
   private MyDTO nested;

   // getters and setters
}

我创建了复合组件，该组件以递归方式调用自身。我这样称呼它：

<screen:my-dto-screen dto="#{myDTOBean.myDto}" />

定义是：

  <composite:interface>
    <composite:attribute name="dto"/>
</composite:interface>
        -- display "someData" here --
    <p:panel rendered="#{cc.attrs.dto.nested != null}" /> -- this acts as recursion bottom --
       <screen:my-dto-screen dto="#{cc.attrs.dto.nested}" />            
    </p:panel>
<composite:implementation>

真正的代码并非如此简单，但是我编写此代码是为了让您简单了解问题所在。一切似乎都很好，但是我看到了一些奇怪的异常。

javax.servlet.ServletException
javax.faces.webapp.FacesServlet.service(FacesServlet.java:422)
org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:79)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:368)
cayetano.games.common.web.security.OperatorPermissionsFilter.doFilter(OperatorPermissionsFilter.java:74)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109)
org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:97)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:100)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:78)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:35)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
cayetano.games.common.web.security.WebUsernamePasswordAuthenticationFilter.actualDoFilter(WebUsernamePasswordAuthenticationFilter.java:65)
cayetano.games.common.web.security.WebUsernamePasswordAuthenticationFilter.doFilter(WebUsernamePasswordAuthenticationFilter.java:43)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:79)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:169)
org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237)
org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167)

root cause

java.lang.StackOverflowError
java.util.regex.Pattern$Curly.match(Pattern.java:3754)
java.util.regex.Pattern$BmpCharProperty.match(Pattern.java:3383)
java.util.regex.Pattern$Slice.match(Pattern.java:3499)
java.util.regex.Pattern$GroupTail.match(Pattern.java:4244)
java.util.regex.Pattern$BranchConn.match(Pattern.java:4095)
java.util.regex.Pattern$BmpCharProperty.match(Pattern.java:3383)
java.util.regex.Pattern$Branch.match(Pattern.java:4131)
java.util.regex.Pattern$GroupHead.match(Pattern.java:4185)
java.util.regex.Pattern$CharProperty.match(Pattern.java:3362)
java.util.regex.Pattern$Start.match(Pattern.java:3072)
java.util.regex.Matcher.search(Matcher.java:1116)
java.util.regex.Matcher.find(Matcher.java:552)
com.sun.faces.el.ELUtils.isCompositeComponentExpr(ELUtils.java:195)
com.sun.faces.facelets.tag.TagAttributeImpl.getValueExpression(TagAttributeImpl.java:388)
com.sun.faces.facelets.tag.TagAttributeImpl.getValueExpression(TagAttributeImpl.java:351)
com.sun.faces.facelets.tag.jsf.CompositeComponentTagHandler$CompositeComponentRule$CompositeExpressionMetadata.applyMetadata(CompositeComponentTagHandler.java:588)
com.sun.faces.facelets.tag.MetadataImpl.applyMetadata(MetadataImpl.java:81)
javax.faces.view.facelets.MetaTagHandler.setAttributes(MetaTagHandler.java:129)
javax.faces.view.facelets.DelegatingMetaTagHandler.setAttributes(DelegatingMetaTagHandler.java:102)
com.sun.faces.facelets.tag.jsf.CompositeComponentTagHandler.setAttributes(CompositeComponentTagHandler.java:226)
com.sun.faces.facelets.tag.jsf.CompositeComponentTagHandler.applyNextHandler(CompositeComponentTagHandler.java:183)
com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:188)
javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120)
javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:98)
javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:137)
com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:188)
javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120)
javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:98)
javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:137)
com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:188)
javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120)
javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:98)
javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:137)
com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:188)
javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120)
com.sun.faces.facelets.tag.composite.ImplementationHandler.apply(ImplementationHandler.java:81)
javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:98)
com.sun.faces.facelets.compiler.NamespaceHandler.apply(NamespaceHandler.java:93)
com.sun.faces.facelets.compiler.EncodingHandler.apply(EncodingHandler.java:86)
com.sun.faces.facelets.impl.DefaultFacelet.apply(DefaultFacelet.java:152)
com.sun.faces.facelets.tag.jsf.CompositeComponentTagHandler.applyCompositeComponent(CompositeComponentTagHandler.java:349)
com.sun.faces.facelets.tag.jsf.CompositeComponentTagHandler.applyNextHandler(CompositeComponentTagHandler.java:190)
com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:188)
javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120)
javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:137)
com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:188)
javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120)
javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:98)
javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:137)
com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:188)
javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120)
javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:98)
javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:137)
com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:188)
javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120)
com.sun.faces.facelets.tag.composite.ImplementationHandler.apply(ImplementationHandler.java:81)
javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:98)
com.sun.faces.facelets.compiler.NamespaceHandler.apply(NamespaceHandler.java:93)
com.sun.faces.facelets.compiler.EncodingHandler.apply(EncodingHandler.java:86)
com.sun.faces.facelets.impl.DefaultFacelet.apply(DefaultFacelet.java:152)
com.sun.faces.facelets.tag.jsf.CompositeComponentTagHandler.applyCompositeComponent(CompositeComponentTagHandler.java:349)
com.sun.faces.facelets.tag.jsf.CompositeComponentTagHandler.applyNextHandler(CompositeComponentTagHandler.java:190)
com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:188)
javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120)
javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:137)
com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:188)
javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120)
javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:98)
javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:137)
com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:188)
javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120)
javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:98)
javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:137)
com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:188)
javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:120)
com.sun.faces.facelets.tag.composite.ImplementationHandler.apply(ImplementationHandler.java:81)
jsf recursion jsf-2 primefaces composite-component
2个回答
2
投票

此异常在视图构建期间发生。在视图构建期间，对rendered属性进行了评估。仅在视图渲染期间（以及在输入和命令组件上的“应用请求值”阶段，但仅此而已）进行评估。因此，您的方法将最终陷入无限递归循环，最终最终导致内存中的堆栈溢出。基本上，您想在视图构建期间评估条件。因此，您需要在视图构建期间运行的标记/属性。其中之一是JSTL <c:if>。

<c:if test="#{cc.attrs.dto.nested != null}"> <p:panel> <screen:my-dto-screen dto="#{cc.attrs.dto.nested}" /> </p:panel> </c:if> 

但是，如果#{cc.attrs.dto.nested}值是由render-time属性提供的，则此方法不起作用，因此递归将不起作用。仅显示顶级组件。您正在寻找一种迭代方法。考虑查看现有的JSF树组件，例如PrimeFaces的<p:tree>。
0
投票
我遇到了与OP类似的问题，并设法通过foreach和BalusC提供的以下博客文章解决了这个问题。以下所有内容均引用此来源，且全部归功于BalusC：
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