001// Copyright 2006, 2010, 2013 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.ioc.services;
016
017import java.lang.annotation.Annotation;
018
019/**
020 * A wrapper around the JavaBean Introspector that allows more manageable access to JavaBean properties of objects.
021 * <p/>
022 * Only provides access to <em>simple</em> properties. Indexed properties are ignored.
023 * <p>
024 * Starting in Tapestry 5.2, public fields can now be accessed as if they were properly JavaBean properties. Where there
025 * is a name conflict, the true property will be favored over the field access.
026 */
027public interface PropertyAccess
028{
029    /**
030     * Reads the value of a property.
031     *
032     * @throws UnsupportedOperationException
033     *             if the property is write only
034     * @throws IllegalArgumentException
035     *             if property does not exist
036     */
037    Object get(Object instance, String propertyName);
038
039    /**
040     * Updates the value of a property.
041     *
042     * @throws UnsupportedOperationException
043     *             if the property is read only
044     * @throws IllegalArgumentException
045     *             if property does not exist
046     */
047    void set(Object instance, String propertyName, Object value);
048
049    /**
050     * Returns the annotation of a given property for the specified type if such an annotation is present, else null.
051     * A convenience over invoking {@link #getAdapter(Object)}.{@link ClassPropertyAdapter#getPropertyAdapter(String)}.{@link PropertyAdapter#getAnnotation(Class)}
052     *
053     * @param instance     the object to read a value from
054     * @param propertyName the name of the property to read (case is ignored)
055     * @param annotationClass the type of annotation to return
056     * @throws IllegalArgumentException
057     *             if property does not exist
058     *
059     * @since 5.4
060     */
061    Annotation getAnnotation(Object instance, String propertyName, Class<? extends Annotation> annotationClass);
062
063    /**
064     * Returns the adapter for a particular object instance. A convienience over invoking {@link #getAdapter(Class)}.
065     */
066    ClassPropertyAdapter getAdapter(Object instance);
067
068    /**
069     * Returns the adapter used to access properties within the indicated class.
070     */
071    ClassPropertyAdapter getAdapter(Class forClass);
072
073    /**
074     * Discards all stored property access information, discarding all created class adapters.
075     */
076    void clearCache();
077}