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}