    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005// http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.commons.services;
    014
    015import java.lang.annotation.Annotation;
    016
    017/**
    018 * A wrapper around the JavaBean Introspector that allows more manageable access to JavaBean properties of objects.
    019 *
    020 * Only provides access to <em>simple</em> properties. Indexed properties are ignored.
    021 *
    022 * Starting in Tapestry 5.2, public fields can now be accessed as if they were properly JavaBean properties. Where there
    023 * is a name conflict, the true property will be favored over the field access.
    024 */
    025public interface PropertyAccess
    026{
    027    /**
    028     * Reads the value of a property.
    029     *
    030     * @throws UnsupportedOperationException
    031     *             if the property is write only
    032     * @throws IllegalArgumentException
    033     *             if property does not exist
    034     */
    035    Object get(Object instance, String propertyName);
    036
    037    /**
    038     * Updates the value of a property.
    039     *
    040     * @throws UnsupportedOperationException
    041     *             if the property is read only
    042     * @throws IllegalArgumentException
    043     *             if property does not exist
    044     */
    045    void set(Object instance, String propertyName, Object value);
    046
    047    /**
    048     * Returns the annotation of a given property for the specified type if such an annotation is present, else null.
    049     * A convenience over invoking {@link #getAdapter(Object)}.{@link ClassPropertyAdapter#getPropertyAdapter(String)}.{@link PropertyAdapter#getAnnotation(Class)}
    050     *
    051     * @param instance     the object to read a value from
    052     * @param propertyName the name of the property to read (case is ignored)
    053     * @param annotationClass the type of annotation to return
    054     * @throws IllegalArgumentException
    055     *             if property does not exist
    056     *
    057     * @since 5.4
    058     */
    059    Annotation getAnnotation(Object instance, String propertyName, Class<? extends Annotation> annotationClass);
    060
    061    /**
    062     * Returns the adapter for a particular object instance. A convienience over invoking {@link #getAdapter(Class)}.
    063     */
    064    ClassPropertyAdapter getAdapter(Object instance);
    065
    066    /**
    067     * Returns the adapter used to access properties within the indicated class.
    068     */
    069    ClassPropertyAdapter getAdapter(Class forClass);
    070
    071    /**
    072     * Discards all stored property access information, discarding all created class adapters.
    073     */
    074    void clearCache();
    075}