ui:repeat不适用于Map [英] ui:repeat doesn't work with Map
问题描述
我有一个键/值的Map，我在@PostConstruct中对其进行了如下初始化:
I have a Map of key / values, which I initialize in @PostConstruct as follows:
Map<String, String> myMap;
@PostConstruct
public void init() {
myMap=new LinkedHashMap<String, String>();
myMap.put("myKey","myValue");
}
public Map<String, String> getMyMap() {
return myMap;
}
public void setMyMap(Map<String, String> myMap) {
this.myMap = myMap;
}
当我尝试使用<ui:repeat>遍历此Map时，如下图所示，并且在Map的getter上设置了一个断点，我注意到它没有被调用，因此什么也没打印:
When I try to iterate over this Map with <ui:repeat> like shown bellow, and I set a break point on the getter for the Map, I notice that it is not getting called, and so nothing is printed:
<ice:panelGroup>
<ui:repeat items="#{myBean.myMap}" var="entry" varStatus="loop">
<input type="checkbox" name="myCheckBoxes" value="#{entry.value}" />
<span class="#{fn:contains(entry.value,'g') ? 'bold-style' : ''}">#{entry.key}</span>
</ui:repeat>
</ice:panelGroup>
但是当用<c:foreach>替换上面的代码时，一切正常，并且列表按预期打印，为什么我会出现这种行为?
But when replacing above code with <c:foreach>, everything works fine, and the list is printed as expected, any ideas why I am getting such behavior?
推荐答案
UPDATE: JSF 2.3 (since 2017) supports this out of the box.
不幸的是，UIData和UIRepeat不支持在JSF中迭代地图.
Unfortunately, UIData and UIRepeat have no support for iterating over a map in JSF.
如果这困扰您(我想是的)，请对以下问题进行投票，并在可能的情况下发表评论，以说明您对此的看法:
If this bothers you (I guess it does), please vote for the following issue and if possible leave a comment that explains how you feel about this:
http://java.net/jira/browse/JAVASERVERFACES_SPEC_PUBLIC-479
同时，您可以使用一些辅助代码来遍历Map:
In the mean time, you can iterate over a Map with some little helper code:
/**
* Converts a Map to a List filled with its entries. This is needed since
* very few if any JSF iteration components are able to iterate over a map.
*/
public static <T, S> List<Map.Entry<T, S>> mapToList(Map<T, S> map) {
if (map == null) {
return null;
}
List<Map.Entry<T, S>> list = new ArrayList<Map.Entry<T, S>>();
list.addAll(map.entrySet());
return list;
}
然后在*-taglib.xml文件中定义EL函数，如下所示:
Then define an EL function in a *-taglib.xml file like this:
<namespace>http://example.com/util</namespace>
<function>
<function-name>mapToList</function-name>
<function-class>com.example.SomeClass</function-class>
<function-signature>java.util.List mapToList(java.util.Map)</function-signature>
</function>
最后像这样在Facelet上使用它:
And finally use it on a Facelet like this:
<html xmlns:util="http://example.com/util">
<ui:repeat value="#{util:mapToList(someDate)}" var="entry" >
Key = #{entry.key} Value = #{entry.value} <br/>
</ui:repeat>
这篇关于ui:repeat不适用于Map的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
