如何创建将Collection绑定到h:selectOneMenu和h:selectManyListbox的JSF复合组件? [英] How can I create a JSF composite component that binds a Collection to both an h:selectOneMenu and h:selectManyListbox?
问题描述
我正在尝试创建一个复合组件，该组件将允许用户在h:singleSelectMenu和h:selectManyListbox之间切换.我有它的工作.只要value字段指向Collection，它就起作用...如果value字段为null，则不起作用.
I'm trying to create a composite component that will allow the user to toggle between a h:singleSelectMenu and h:selectManyListbox. I have it working sort of. It works as long as the value field points to a Collection...it does NOT work if the value field is null.
singleMultiSelect.xhtml
<?xml version="1.0" encoding="US-ASCII"?>
<!DOCTYPE html>
<ui:composition
xmlns:f="http://xmlns.jcp.org/jsf/core"
xmlns:h="http://xmlns.jcp.org/jsf/html"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:cc="http://java.sun.com/jsf/composite"
xmlns:c="http://java.sun.com/jstl/core"
xmlns:ace="http://www.icefaces.org/icefaces/components"
>
<cc:interface componentType="singleMultiSelect">
<!-- The initial list of objects -->
<cc:attribute name="list" type="java.util.List" required="true"/>
<!-- The selected objects -->
<cc:attribute name="selected" type="java.util.Collection" required="true"/>
<!-- whether to display the selectOneMenu (true) or selectManyBox (false) -->
<cc:attribute name="singleSelect" type="java.lang.Boolean"
required="false" default="true"/>
</cc:interface>
<cc:implementation>
<span id="#{cc.clientId}">
<ace:checkboxButton id="singleSelectChkBx"
value="#{cc.attrs.singleSelect}">
<ace:ajax render="#{cc.clientId}"/>
</ace:checkboxButton>
<h:selectOneMenu id="selectOneMenu"
rendered="#{cc.attrs.singleSelect}"
value="#{cc.singleSelected}">
<f:selectItems value="#{cc.attrs.list}"/>
</h:selectOneMenu>
<h:selectManyListbox id="selectManyListbox"
rendered="#{! cc.attrs.singleSelect}"
value="#{cc.attrs.selected}">
<f:selectItems value="#{cc.attrs.list}"/>
</h:selectManyListbox>
</span>
</cc:implementation>
</ui:composition>
SingleMultiSelect.java
public class SingleMultiSelect extends UINamingContainer {
public SingleMultiSelect() {
super();
}
/**
* Converts the Object selected within the selectOneMenu to the list
* used by the component.
*
* @param singleSelected
*/
public void setSingleSelected(Object singleSelected) {
getSelected().clear();
if(singleSelected != null) {
getSelected().add(singleSelected);
}
}
/**
* Converts the collection used by the component to a single
* Object selected within the selectOneMenu.
*
* @return
*/
public Object getSingleSelected() {
return getSelected().size() > 0 ? getSelected().iterator().next() : null;
}
private Collection getSelected() {
return (Collection) getAttributes().get("selected");
}
}
我尝试写入属性映射，但这没用
I tried writing to the attributes map but that didn't work
public void setSingleSelected(Object singleSelected) {
HashSet selected = new HashSet();
selected.add(singleSelected);
((Collection) getAttributes()).put("selected", selected);
}
推荐答案
getAttributes().put("selected", selected);
您基本上是用HashSet覆盖基础的ValueExpression对象#{cc.attrs.selected}.换句话说，EL表达式成为一个硬编码"值，并且不再具有bean属性.
You're basically overriding the underlying ValueExpression object #{cc.attrs.selected} with a HashSet. In other words, the EL expression became a "hardcoded" value and can't reach the bean property anymore.
您应该获取ValueExpression并通过setValue()调用来调用setter.
You should be obtaining the ValueExpression and invoke the setter via setValue() call.
getValueExpression("selected").setValue(context.getElContext(), selected);
无关与具体问题无关，在实现支持组件时，最好像UI组件而不是支持bean那样思考.不要直接操作模型(复合属性)，而是要通过binding到达复合组件自己的组件.此外，请勿触摸吸气剂/吸气剂.替换<h:selectOneMenu value>如下:
Unrelated to the concrete problem, when implementing a backing component, it's better to think like an UI component, not a backing bean. Don't manipulate the model directly (the composite attributes), but the composite component's own components which you reach via binding. Moreover, do not touch the getters/setters. Replace the <h:selectOneMenu value> as below:
<h:selectOneMenu binding="#{cc.singleSelected}" ...>
private UISelectOne singleSelected; // +getter+setter
@Override
public void processUpdates(FacesContext context) {
super.processUpdates(context);
if (getAttributes().get("singleSelect") == Boolean.TRUE) {
HashSet selected = new HashSet();
if (singleSelected.getValue() != null) {
selected.add(singleSelected.getValue());
}
getValueExpression("selected").setValue(context.getELContext(), selected);
}
}
@Override
public void encodeBegin(FacesContext context) throws IOException {
if (getAttributes().get("singleSelect") == Boolean.TRUE) {
Collection selected = (Collection) getAttributes().get("selected");
if (selected != null && !selected.isEmpty()) {
singleSelected.setValue(selected.iterator().next());
} else {
singleSelected.setValue(null);
}
}
super.encodeBegin(context);
}
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