如何以编程方式生成primefaces PickList组件？

Question

public void populateForm(ComponentSystemEvent event) {
    HtmlForm form = (HtmlForm) event.getComponent();

    List<String> citiesSource = new ArrayList<String>();
    List<String> citiesTarget = new ArrayList<String>();
    citiesSource.add("San Francisco");
    citiesSource.add("London");
    citiesSource.add("Paris");
    citiesSource.add("Istanbul");
    citiesSource.add("Berlin");
    citiesSource.add("Barcelona");
    citiesSource.add("Rome");

    cities = new DualListModel<String>(citiesSource, citiesTarget);

    PickList pickList = new PickList();
    pickList.setId("pickList");
    pickList.setValue(cities);
    pickList.setVar("cities");
    pickList.setItemLabel(pickList.getVar());
    pickList.setItemValue(cities);

     form.getChildren().add(pickList);
}

这是我的方法，我得到的输出是：

​

​

但是，如果我将<p:pickList id="pickList" value="#{bean.cities}" var="cities" itemLabel="#{cities}" itemValue="#{cities}" />添加到xhtml中，就会得到以下输出：

​

​

这里发生什么事情？

Answer 1

我就是这样解决PickList问题的：

FacesContext context = FacesContext.getCurrentInstance();
ExpressionFactory ef = context.getApplication().getExpressionFactory();

PickList pickList = new PickList();

ValueExpression pickListValue = ef.createValueExpression(
    context.getELContext(), "#{ruleManagedBean.cities}",DualListModel.class);

ValueExpression pickListVar = ef.createValueExpression(
            context.getELContext(), "cities", String.class);

ValueExpression pickListItemLabel = ef.createValueExpression(
            context.getELContext(), "#{cities}", String.class);

ValueExpression pickListItemValue = ef.createValueExpression(
            context.getELContext(), "#{cities}", String.class);

pickList.setId("pickList");
pickList.setValueExpression("value", pickListValue);
pickList.setValueExpression("var", pickListVar);
pickList.setValueExpression("itemLabel", pickListItemLabel);
pickList.setValueExpression("itemValue", pickListItemValue);

form.getChildren().add(pickList);

注意： ruleManagedBean.cities引用DualListModel，填充为

List<String> citiesSource = new ArrayList<String>();
List<String> citiesTarget = new ArrayList<String>();
citiesSource.add("San Francisco");
citiesSource.add("London");
citiesSource.add("Paris");
citiesSource.add("Istanbul");
citiesSource.add("Berlin");
citiesSource.add("Barcelona");
citiesSource.add("Rome");

cities.setSource(citiesSource);
cities.setTarget(citiesTarget);

确保您已经全局声明了这个DualListModel，如下所示，并且有getter setter方法

private DualListModel<String> cities = new DualListModel<String>();

Answer 2

与PickList pickList = new PickList();不同，请尝试如下：

Application application = FacesContext.getCurrentInstance().getApplication();
PickList pickList = (PickList) application.createComponent(PickList.COMPONENT_TYPE);

为此更改您的pickList.setValue(cities);：

注意：城市必须是您的bean上的一个字段，它具有自己的getter。

ExpressionFactory ef = application.getExpressionFactory();
ELContext elc = FacesContext.getCurrentInstance().getELContext();
ValueExpression value = ef.createValueExpression(elc, "#{bean.cities}", DualListModel.class);
pickList.setValueExpression("value", value);