name.martingeisse.wicket.model.ClassDisplayNameModel.java Source code

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Here is the source code for name.martingeisse.wicket.model.ClassDisplayNameModel.java

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/**
 * Copyright (c) 2011 Martin Geisse
 *
 * This file is distributed under the terms of the MIT license.
 */

package name.martingeisse.wicket.model;

import name.martingeisse.common.terms.DisplayName;
import org.apache.wicket.model.AbstractReadOnlyModel;
import org.apache.wicket.model.IModel;

/**
 * This is a read-only model that wraps an inner model which returns either a string
 * (a class name) or a class object. This model then returns a display name for
 * that class, which is:
 * - null if the inner model returns null
 * - the inner model value if the inner model returns an unknown class name
 * - the DisplayName value if the inner model returns a class object or known class name and that class has such an annotation
 * - the canonical class name if the inner model returns a class object or known class name and that class has no DisplayName annotation
 */
public class ClassDisplayNameModel extends AbstractReadOnlyModel<String> {

    /**
     * the inner
     */
    private IModel<?> inner;

    /**
     * Constructor.
     */
    private ClassDisplayNameModel(IModel<?> inner) {
        this.inner = inner;
    }

    /**
     * Creates a new instance that returns the display name of a class from the specified model.
     * @param classModel the model that provides the class
     * @return the display name model
     */
    public static ClassDisplayNameModel fromClassModel(IModel<Class<?>> classModel) {
        return new ClassDisplayNameModel(classModel);
    }

    /**
     * Creates a new instance that returns the display name of a class with the name taken
     * from the specified model.
     * @param classNameModel the model that provides the class name
     * @return the display name model
     */
    public static ClassDisplayNameModel fromClassNameModel(IModel<String> classNameModel) {
        return new ClassDisplayNameModel(classNameModel);
    }

    /* (non-Javadoc)
     * @see org.apache.wicket.model.AbstractReadOnlyModel#getObject()
     */
    @Override
    public String getObject() {
        Object o = inner.getObject();
        if (o == null) {
            return null;
        } else if (o instanceof Class<?>) {
            return getObject((Class<?>) o);
        } else if (o instanceof String) {
            String s = (String) o;
            try {
                return getObject(Class.forName(s));
            } catch (ClassNotFoundException e) {
                return s;
            }
        } else {
            throw new RuntimeException("inner model of ClassDisplayNameModel returned invalid object: " + o);
        }
    }

    /**
     * @param c
     * @return
     */
    private static String getObject(Class<?> c) {
        DisplayName annotation = c.getAnnotation(DisplayName.class);
        return (annotation != null ? annotation.value() : c.getCanonicalName());
    }

    /* (non-Javadoc)
     * @see org.apache.wicket.model.AbstractReadOnlyModel#detach()
     */
    @Override
    public void detach() {
        inner.detach();
        super.detach();
    }

}