[英]Find component by ID in JSF
I want to find some UIComponent
from managed bean by the id that I have provided. 我想通过提供的ID从托管bean中找到一些UIComponent
。
I have written the following code: 我写了以下代码:
private UIComponent getUIComponent(String id) {
return FacesContext.getCurrentInstance().getViewRoot().findComponent(id) ;
}
I have defined a p:inputTextarea
as: 我已经将p:inputTextarea
定义为:
<p:inputTextarea id="activityDescription" value="#{adminController.activityDTO.activityDescription}" required="true" maxlength="120"
autoResize="true" counter="counter" counterTemplate="{0} characters remaining." cols="80" rows="2" />
Now if a call to the method as getUIComponent("activityDescription")
it is returning null
, but if I call it as getUIComponent("adminTabView:activityForm:activityDescription")
then I can get the org.primefaces.component.inputtextarea.InputTextarea
instance. 现在,如果以getUIComponent("activityDescription")
的形式调用该方法,则返回null
,但是如果以getUIComponent("adminTabView:activityForm:activityDescription")
的形式调用该方法,则可以得到org.primefaces.component.inputtextarea.InputTextarea
实例。 。
Is there any way to get the component with only the id ie, "activityDescription" not the absolute id ie, "adminTabView:activityForm:activityDescription"? 有什么方法可以获取仅具有ID(即“ activityDescription”)而不是绝对ID(即“ adminTabView:activityForm:activityDescription”)的组件?
You can use the following code: 您可以使用以下代码:
public UIComponent findComponent(final String id) {
FacesContext context = FacesContext.getCurrentInstance();
UIViewRoot root = context.getViewRoot();
final UIComponent[] found = new UIComponent[1];
root.visitTree(new FullVisitContext(context), new VisitCallback() {
@Override
public VisitResult visit(VisitContext context, UIComponent component) {
if (component != null
&& component.getId() != null
&& component.getId().equals(id)) {
found[0] = component;
return VisitResult.COMPLETE;
}
return VisitResult.ACCEPT;
}
});
return found[0];
}
This code will find only the first component in the tree with the id
you pass. 此代码将仅在树中找到具有您传递的id
的第一个组件。 You will have to do something custom if there are 2 components with the same name in the tree (this is possible if they are under 2 different naming containers). 如果树中有2个具有相同名称的组件,则必须做一些自定义操作(如果它们在2个不同的命名容器下,则可能这样做)。
I try this code, and it's help: 我尝试这段代码,它有帮助:
private static UIComponent getUIComponentOfId(UIComponent root, String id){
if(root.getId().equals(id)){
return root;
}
if(root.getChildCount() > 0){
for(UIComponent subUiComponent : root.getChildren()){
UIComponent returnComponent = getUIComponentOfId(subUiComponent, id);
if(returnComponent != null){
return returnComponent;
}
}
}
return null;
}
Thanks 谢谢
Maybe it's not possible. 也许不可能。 The FacesContext.getCurrentInstance().getViewRoot().findComponent(id)
method returns only one UIComponent
. FacesContext.getCurrentInstance().getViewRoot().findComponent(id)
方法仅返回一个UIComponent
。 The ViewRoot is constructed as a tree so if you have two forms in the view, each one with a component with id="text"
, they will have it's parent components added to the id so they won't conflict. ViewRoot构造为一棵树,因此,如果您在视图中有两种形式,每一种形式都有一个id="text"
的组件,则它们会将其父组件添加到id中,这样就不会发生冲突。 If you put the two id="text"
components within the same form, you will have java.lang.IllegalStateException
thrown. 如果将两个id="text"
组件放在相同的表单中,则会引发java.lang.IllegalStateException
。
If you want to find all components with the searched id, you could write a method that implements: 如果要查找具有搜索ID的所有组件,则可以编写一个实现以下方法的方法:
List<UIComponent> foundComponents = new ArrayList();
for(UIComponent component: FacesContext.getCurrentInstance().getViewRoot().getChildren()) {
if(component.getId().contains("activityDescription")){
foundComponents.add(component);
}
}
Or if you want to find the first occurrence: 或者,如果您想查找第一个匹配项:
UIComponent foundComponent;
for(UIComponent component: FacesContext.getCurrentInstance().getViewRoot().getChildren()) {
if(component.getId().contains("activityDescription")){
foundComponent = component;
break;
}
}
只需将prependId="false"
放到该文本区域所在的表单中即可。
Yes, in all parent components which are NamingContainers
you have to add attribute prependId="false"
- it will works in <h:form>
for sure and should work in others. 是的,在所有作为NamingContainers
父组件中,您必须添加属性prependId="false"
-它肯定可以在<h:form>
中工作,并且应该在其他组件中工作。
If it is not possible to set it via attribute in .xhtml file you have to set such value programaticaly. 如果无法通过.xhtml文件中的属性进行设置,则必须以编程方式设置该值。
Suggestion after question's author comment: 问题作者评论后的建议:
If there is not such attribute in components that you are using try write find method like this: 如果要使用的组件中没有这样的属性,请尝试编写以下查找方法:
private UIComponent findComponent(String id, UIComponent where) {
if (where == null) {
return null;
}
else if (where.getId().equals(id)) {
return where;
}
else {
List<UIComponent> childrenList = where.getChildren();
if (childrenList == null || childrenList.isEmpty()) {
return null;
}
for (UIComponent child : childrenList) {
UIComponent result = null;
result = findComponent(id, child);
if(result != null) {
return result;
}
return null;
}
Next just invoke 接下来只是调用
UIComponent iamLookingFor = findComponent(myId, FacesContext.getCurrentInstance().getViewRoot());
That will help? 那会有所帮助吗?
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