Question

Again I would like to get your opinion about a design issue.

I have a JavaBean with 15 attributes. For feeding the attributes I have a for loop that iterates over a collection of key-value pairs (concretely SAML attributes, I am mapping the attributes response to principals attributes). I am invoking the appropriate setter method basis on the key value, this is:

    .../...
    for (SAML2AttributeInfo attr : attrs) {
        if (attr.getAttributeName().equals("http://schemas.xmlsoap.org/ws/2005/05/identity/claims/upn")) {
            customPrincipal.setUpn(attr.getAttributeValues().iterator().next());
        }
        .../... so on and so forth
    }

It works, ok, but I have an ugly piece of code, 15 if-statements like above do not look very elegant.

I am thinking on using Reflection, this is, develop a unique set method and pass it the name of the attribute and his value.

Another option could be store the attributes in a Map, but I am not sure…

Any ideas?

Thanks in advance,

Luis

Answer 1

Polymorphism for the rescue

enum Attribute {
    UPN("http://schemas.xmlsoap.org/ws/2005/05/identity/claims/upn") {
        void setValue(Principal principal, String value) {
            principal.setUpn(value);
        }
    },
    ...
    ;

    private final String name;

    private Attribute(String name) {
        this.name = name;
    }

    public abstract setValue(Principal principal, String name);

    public static Attribute getByName(String name) {
        for (Attribute attribute : values())
            if (attribute.name.equals(name))
                return attribute;

        return null;
    }

    public static void setByName(Principal principal, String name, String value) {
        Attribute attribute = getByName(name);

        if (attribute == null)
            throw new IllegalArgumentException("No such attribute");

        attribute.setValue(principal, value);
    }
}

If you know the attribute you want to set there is no reason to go go via the name:

Attribute.UPN.setValue(principal, "something");