假设这个页面的代码：
<h:form prependId="false" id="form">
<h:selectManyCheckBox id="checkBoxList" value="#{backedBean.lstIdSelectedItems}" layout="pageDirection">
<f:selectItems value="#{backedBean.lstAvailableItems}" var="item" itemLabel="#{item.label}" itemValue="#{item.value}" />
<f:ajax listener="#{backedBean.itemClicked}" />
</h:selectManyCheckBox>
</h:form>
和会话管理bean的代码：
public class BackedBean implements Serializable {
private List<SelectItem> lstAvailableItems;
private List<Long> lstIdSelectedItems;
public BackedBean() {
lstAvailableItems = new ArrayList<SelectItem>();
lstIdSelectedItems = new ArrayList<Long>();
}
@postconstruct
private void postconstruct(){
for (int i = 0; i < 10; i++) {
SelectItem item = new SelectItem(new Long(i),"CHKID " + i);
lstAvailableItems.add(item);
}
}
public void itemClicked(AjaxBehaviorEvent ae){
HtmlSelectManyCheckBox uiCmp = (HtmlSelectManyCheckBox)ae.getSource();
// (1) Here I would like to get the ID of the item that has been clicked.
}
在(1)中,我想获得用户点击的元素的ID.我可以在lstIdSelectedItems数组列表中看到用户选择的所有元素的ID,但是如何获取用户点击的元素的ID？
我曾尝试在selectManyCheckBox中使用f：attribute标记,但在支持的bean中调用ajax listener方法时,该属性不在组件映射中.我用过这个,但不起作用：
<h:selectManyCheckBox id="checkBoxList" value="#{backedBean.lstIdSelectedItems}" layout="pageDirection">
<f:selectItems value="#{backedBean.lstAvailableItems}" var="item" itemLabel="#{item.label}" itemValue="#{item.value}">
<f:attribute name="clicked" value="#{item.value}" />
</f:selectItems>
<f:ajax listener="#{backedBean.itemClicked}" />
</h:selectManyCheckBox>
有任何想法吗？
问候.
因此,您对实际价值变化感兴趣,而不仅仅是新价值.引入一个valuechangelistener,它将旧值与新值进行比较,并准备一些ajax监听器方法可以拦截的属性.
例如.
<h:selectManyCheckBox value="#{bean.selectedItems}" valuechangelistener="#{bean.selectedItemsChanged}" converter="javax.faces.Long">
<f:selectItems value="#{bean.availableItems}" />
<f:ajax listener="#{bean.itemSelected}" />
</h:selectManyCheckBox>
同
private Map<String,Long> availableItems; // +getter
private List<Long> selectedItems; // +getter+setter
private Long selectedItem;
private boolean selectedItemRemoved;
@postconstruct
public void init() {
availableItems = new LinkedHashMap<String,Long>();
for (long i = 0; i < 10; i++) {
availableItems.put("CHKID " + i,i);
}
}
public void selectedItemsChanged(ValueChangeEvent event) {
List<Long> oldValue = (List<Long>) event.getoldValue();
List<Long> newValue = (List<Long>) event.getNewValue();
if (oldValue == null) {
oldValue = Collections.emptyList();
}
if (oldValue.size() > newValue.size()) {
oldValue = new ArrayList<Long>(oldValue);
oldValue.removeAll(newValue);
selectedItem = oldValue.iterator().next();
selectedItemRemoved = true;
}
else {
newValue = new ArrayList<Long>(newValue);
newValue.removeAll(oldValue);
selectedItem = newValue.iterator().next();
selectedItemRemoved = false;
}
}
public void itemSelected(AjaxBehaviorEvent event) {
System.out.println("Selected item: " + selectedItem);
System.out.println("Selected item removed? " + selectedItemRemoved);
}