如何在 f: selectItem 中使用枚举值

You could use <f:selectItems value="#{carBean.carList}" /> and return a list of SelectItem instances that wrap the enum (use Status.values() to get all possible values).

JSF has a builtin converter for enum, so this should do:

@Named
@ApplicationScoped
public class Data {


public Status[] getStatuses() {
return Status.values();
}


}

with

<h:selectOneMenu value="#{bean.question.status}" >
<f:selectItems value="#{data.statuses}" />
</h:selectOneMenu>

(note: since JSF 2.0 there's no need anymore to provide a SelectItem[] or List<SelectItem>, a T[] and List<T> are accepted as well and you can access the current item by var attribute)

If you happen to use JSF utility library OmniFaces, then you could use <o:importConstants> instead of a bean.

<o:importConstants type="com.example.Status" />


<h:selectOneMenu value="#{bean.question.status}" >
<f:selectItems value="#{Status}" />
</h:selectOneMenu>

If you intend to control the labels as well, you could add them to the Status enum:

public enum Status {


SUBMITTED("Submitted"),
REJECTED("Rejected"),
APPROVED("Approved");


private String label;


private Status(String label) {
this.label = label;
}


public String getLabel() {
return label;
}


}

with

<f:selectItems value="#{data.statuses}" var="status"
itemValue="#{status}" itemLabel="#{status.label}" />

Or, better, make the enum value a property key of a localized resource bundle (EL 3.0 required):

<f:selectItems value="#{data.statuses}" var="status"
itemValue="#{status}" itemLabel="#{text['data.status.' += status]}" />

with this in a properties file associated with resource bundle #{text}

data.status.SUBMITTED = Submitted
data.status.REJECTED = Rejected
data.status.APPROVED = Approved

For localization we can use also this solution:

public enum Status { SUBMITTED, REJECTED, APPROVED }


data.status.SUBMITTED=Submitted
data.status.REJECTED=Rejected
data.status.APPROVED=Approved


<h:selectOneMenu value="#{bean.question.status}" >
<f:selectItems
value="#{data.statuses}"
var="status"
itemValue="#{status}"
itemLabel="#{text['data.status.'.concat(status)]}" />
</h:selectOneMenu>

So the resource path for localization strings are not hardcoded in Enum.

You can use following utility el function to obtain the enum values and use them in a SelectOneMenu for example. No need to create beans and boilerplate methods.

public final class ElEnumUtils
{
private ElEnumUtils() { }


/**
* Cached Enumerations, key equals full class name of an enum
*/
private final static Map<String, Enum<?>[]> ENTITY_ENUMS = new HashMap<>();;


/**
* Retrieves all Enumerations of the given Enumeration defined by the
* given class name.
*
* @param enumClassName Class name of the given Enum.
*
* @return
*
* @throws ClassNotFoundException
*/
@SuppressWarnings("unchecked")
public static Enum<?>[] getEnumValues(final String enumClassName) throws ClassNotFoundException
{
// check if already cached - use classname as key for performance reason
if (ElEnumUtils.ENTITY_ENUMS.containsKey(enumClassName))
return ElEnumUtils.ENTITY_ENUMS.get(enumClassName);


final Class<Enum<?>> enumClass = (Class<Enum<?>>) Class.forName(enumClassName);


final Enum<?>[] enumConstants = enumClass.getEnumConstants();


// add to cache
ElEnumUtils.ENTITY_ENUMS.put(enumClassName, enumConstants);


return enumConstants;
}
}

Register it as an el function in a taglib file:

<function>
<description>Retrieves all Enumerations of the given Enumeration defined by the given class name.</description>
<function-name>getEnumValues</function-name>
<function-class>
package.ElEnumUtils
</function-class>
<function-signature>
java.lang.Enum[] getEnumValues(java.lang.String)
</function-signature>
</function>

And finally call it like:

<p:selectOneMenu value="#{bean.type}">
<f:selectItems value="#{el:getEnumValues('package.BeanType')}" var="varEnum"
itemLabel="#{el:getEnumLabel(varEnum)}" itemValue="#{varEnum}"/>
</p:selectOneMenu>

Similiar to BalusC answer you should be using a resource bundle with localized enum labels and for cleaner code you can also create a function like getEnumLabel(enum)