我需要在 JSF 2 中以编程方式创建复合组件。 经过几天的搜索和实验,我找到了这个方法(受到 java.net 上的 Lexi 的高度启发):
/**
* Method will attach composite component to provided component
* @param viewPanel parent component of newly created composite component
*/
public void setComponentJ(UIComponent viewPanel) {
FacesContext context = FacesContext.getCurrentInstance();
viewPanel.getChildren().clear();
// load composite component from file
Resource componentResource = context.getApplication().getResourceHandler().createResource("whatever.xhtml", "components/form");
UIComponent composite = context.getApplication().createComponent(context, componentResource);
// push component to el
composite.pushComponentToEL(context, composite);
boolean compcompPushed = false;
CompositeComponentStackManager ccStackManager = CompositeComponentStackManager.getManager(context);
compcompPushed = ccStackManager.push(composite, CompositeComponentStackManager.StackType.TreeCreation);
// Populate the component with value expressions
Application application = context.getApplication();
composite.setValueExpression("value", application.getExpressionFactory().createValueExpression(
context.getELContext(), "#{stringValue.value}",
String.class));
// Populate the component with facets and child components (Optional)
UIOutput foo = (UIOutput) application.createComponent(HtmlOutputText.COMPONENT_TYPE);
foo.setValue("Foo");
composite.getFacets().put("foo", foo);
UIOutput bar = (UIOutput) application.createComponent(HtmlOutputText.COMPONENT_TYPE);
bar.setValue("Bar");
composite.getChildren().add(bar);
// create composite components Root
UIComponent compositeRoot = context.getApplication().createComponent(UIPanel.COMPONENT_TYPE);
composite.getAttributes().put(Resource.COMPONENT_RESOURCE_KEY, componentResource);
compositeRoot.setRendererType("javax.faces.Group");
composite.setId("compositeID");
try {
FaceletFactory factory = (FaceletFactory) RequestStateManager.get(context, RequestStateManager.FACELET_FACTORY);
Facelet f = factory.getFacelet(componentResource.getURL());
f.apply(context, compositeRoot); //<==[here]
} catch (Exception e) {
log.debug("Error creating composite component!!", e);
}
composite.getFacets().put(
UIComponent.COMPOSITE_FACET_NAME, compositeRoot);
// attach composite component to parent componet
viewPanel.getChildren().add(composite);
// pop component from el
composite.popComponentFromEL(context);
if (compcompPushed) {
ccStackManager.pop(CompositeComponentStackManager.StackType.TreeCreation);
}
}
问题是此代码仅在javax.faces.PROJECT_STAGE
设置为时才对我有用PRODUCTION
(我花了一整天的时间才弄明白)。如果javax.faces.PROJECT_STAGE
设置为DEVELOPMENT
在标记点 ( <==[here]
)上抛出异常:
javax.faces.view.facelets.TagException: /resources/components/form/pokus.xhtml @8,19 <cc:interface> Component Not Found for identifier: j_id2.getParent().
at com.sun.faces.facelets.tag.composite.InterfaceHandler.validateComponent(InterfaceHandler.java:135)
at com.sun.faces.facelets.tag.composite.InterfaceHandler.apply(InterfaceHandler.java:125)
at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:98)
at com.sun.faces.facelets.compiler.NamespaceHandler.apply(NamespaceHandler.java:93)
at com.sun.faces.facelets.compiler.EncodingHandler.apply(EncodingHandler.java:82)
at com.sun.faces.facelets.impl.DefaultFacelet.apply(DefaultFacelet.java:152)
at cz.boza.formcreator.formcore.Try.setComponentJ(Try.java:83)
at cz.boza.formcreator.formcore.FormCreator.<init>(FormCreator.java:40)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:532)
compositeRoot
组件中设置的父级存在一些问题(j_id2
是自动生成的 ID compositeRoot
)。此外,这段代码没有经过足够彻底的测试,所以我不确定我是否可以依赖它。
我认为能够以编程方式操作复合组件非常重要。否则复合组件一半没用。
我无法详细解释具体问题,但我只能观察并确认问题中所示的方法笨拙且与 Mojarra 紧密耦合。有
com.sun.faces.*
需要 Mojarra 的特定依赖项。这种方法没有使用标准的 API 方法,此外,在其他 JSF 实现(如 MyFaces)中也不起作用。这是一种使用标准 API 提供的方法的更简单的方法。关键是您应该使用
FaceletContext#includeFacelet()
在给定的父级中包含复合组件资源。public static void includeCompositeComponent(UIComponent parent, String libraryName, String resourceName, String id) { // Prepare. FacesContext context = FacesContext.getCurrentInstance(); Application application = context.getApplication(); FaceletContext faceletContext = (FaceletContext) context.getAttributes().get(FaceletContext.FACELET_CONTEXT_KEY); // This basically creates <ui:component> based on <composite:interface>. Resource resource = application.getResourceHandler().createResource(resourceName, libraryName); UIComponent composite = application.createComponent(context, resource); composite.setId(id); // Mandatory for the case composite is part of UIForm! Otherwise JSF can't find inputs. // This basically creates <composite:implementation>. UIComponent implementation = application.createComponent(UIPanel.COMPONENT_TYPE); implementation.setRendererType("javax.faces.Group"); composite.getFacets().put(UIComponent.COMPOSITE_FACET_NAME, implementation); // Now include the composite component file in the given parent. parent.getChildren().add(composite); parent.pushComponentToEL(context, composite); // This makes #{cc} available. try { faceletContext.includeFacelet(implementation, resource.getURL()); } catch (IOException e) { throw new FacesException(e); } finally { parent.popComponentFromEL(context); } }
假设您想
<my:testComposite id="someId">
从 URI包含xmlns:my="http://java.sun.com/jsf/composite/mycomponents"
,然后按如下方式使用它:includeCompositeComponent(parent, "mycomponents", "testComposite.xhtml", "someId");
这也已作为(自 V1.5 起)添加到 JSF 实用程序库OmniFaces中
Components#includeCompositeComponent()
。自 JSF 2.2 起更新,
ViewDeclarationLanguage
该类获得了一个createComponent()
采用 taglib URI 和标签名称的新方法,该方法也可用于此目的。因此,如果您使用的是 JSF 2.2,则应按如下方式完成该方法:public static void includeCompositeComponent(UIComponent parent, String taglibURI, String tagName, String id) { FacesContext context = FacesContext.getCurrentInstance(); UIComponent composite = context.getApplication().getViewHandler() .getViewDeclarationLanguage(context, context.getViewRoot().getViewId()) .createComponent(context, taglibURI, tagName, null); composite.setId(id); parent.getChildren().add(composite); }
假设您想
<my:testComposite id="someId">
从 URI包含xmlns:my="http://xmlns.jcp.org/jsf/composite/mycomponents"
,然后按如下方式使用它:includeCompositeComponent(parent, "http://xmlns.jcp.org/jsf/composite/mycomponents", "testComposite", "someId");