如何在ajax方法中获取单击的项目？

发布时间：2020-12-16 03:07:41 所属栏目：百科来源：网络整理

导读：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="#{it

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);
}

（编辑：李大同）

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