EL枚举字符串处理

Question

I have a variable being passed to my JSP view from a spring controller that maps to an enum. It is being printed out at 'ENUM_VALUE', not very user friendly.

What is the best way to convert this to a more readable form like 'Enum value'.

I'd rather a pure EL solution so as to avoid writting more code in the controller to parse this, but all comments are appreciated.

Answer 1

That value is coming from Enum#name() method. Just add a getter to your enum which returns the friendly name. Eg

public String getFriendlyName() {
    return name().toLowerCase().replace("_", " ");
}

You can use it in EL like ${bean.someEnum.friendlyName} .

Answer 2

I'd add for every enum a description text when you define them. Something like this.

public enum MyEnum {

    ENUM_VALUE("your friendly enum value");

    private String description;

    //constructor
    private MyEnum(String description) {
        this.description = description;
    }

    //add a getter for description
}

your EL would look like ${yourenum.description}

Answer 3

Like Kacper86 said, the 2.1 specification says that Enum-to-String coercion should call .name() instead of toString() . I was unable to get BalusC's answer to work.

Personally, I prefer using an EL function instead of tacking on a getDescription method to my enum. I find that I usually always override the toString() method, so adding another method to get the same value seems like a bad design. If I'm working in Java, I just call toString() , so my problem is solely in the EL realm. Also, an EL function makes it so that you don't have to modify your enum class every time you want to print out a new enum on your web page; you just reuse your EL function for any enum.

Here's some simple code to create an EL function:

public final class JSTLUtilityFunctions 
{
    public static String enumToStr(Enum<?> enumInst) {
        return enumInst.toString();
    }
}

In your TLD:

<taglib>
    <!-- Other stuff... -->
    <function>
        <name>enumToStr</name>
        <function-class>yourpackage.JSTLUtilityFunctions</function-class>
        <function-signature>java.lang.String enumToStr(java.lang.Enum)</function-signature>
    </function>
</taglib>

Usage:

<%@taglib prefix="util" uri="your-TLD-uri.tld" %>
<span>${ util:enumToStr(myEnumInstance) }</span>

Obviously, you could change the method signature to accept any instance of Object if you wanted.

Answer 4

你可以在jsp中做这样的事情：

<span>${myenum.toString()}</span>