    001// Copyright 2006, 2007, 2010, 2011, 2014 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;
    016
    017import org.apache.tapestry5.ioc.annotations.Inject;
    018
    019import java.lang.annotation.Annotation;
    020
    021/**
    022 * Defines an object which can provide access to services defined within a {@link org.apache.tapestry5.ioc.Registry}, or
    023 * to objects or object instances available by other means. Services are accessed via service id, or
    024 * (when appropriate)
    025 * by just service interface. The Registry itself implements this interface, as does
    026 * {@link org.apache.tapestry5.ioc.ServiceResources}.
    027 */
    028public interface ObjectLocator
    029{
    030    /**
    031     * Obtains a service via its unique service id. Returns the service's proxy. The service proxy
    032     * implements the same
    033     * interface as the actual service, and is used to instantiate the actual service only as needed
    034     * (this is
    035     * transparent to the application).
    036     *
    037     * @param <T>
    038     * @param serviceId        unique Service id used to locate the service object (may contain <em>symbols</em>,
    039     *                         which
    040     *                         will be expanded), case is ignored
    041     * @param serviceInterface the interface implemented by the service (or an interface extended by the service
    042     *                         interface)
    043     * @return the service instance
    044     * @throws RuntimeException if the service is not defined, or if an error occurs instantiating it
    045     */
    046    <T> T getService(String serviceId, Class<T> serviceInterface);
    047
    048    /**
    049     * Locates a service given a service interface and (optionally) some marker annotation types. A single service must implement the service
    050     * interface (which                                                   * can be hard to guarantee) and by marked by all the marker types. The search takes into account inheritance of the service interface
    051     * (not the service <em>implementation</em>), which may result in a failure due to extra
    052     * matches.
    053     *
    054     * @param serviceInterface the interface the service implements
    055     * @return the service's proxy
    056     * @throws RuntimeException if the service does not exist (this is considered programmer error), or multiple
    057     *                          services directly implement, or extend from, the service interface
    058     * @see org.apache.tapestry5.ioc.annotations.Marker
    059     */
    060    <T> T getService(Class<T> serviceInterface);
    061
    062    /**
    063     * Locates a service given a service interface and (optionally) some marker annotation types. A single service must implement the service
    064     * interface (which                                                   * can be hard to guarantee) and by marked by all the marker types. The search takes into account inheritance of the service interface
    065     * (not the service <em>implementation</em>), which may result in a failure due to extra
    066     * matches.        The ability to specify marker annotation types was added in 5.3
    067     *
    068     * @param serviceInterface the interface the service implements
    069     * @param markerTypes      Markers used to select a specific service that implements the interface
    070     * @return the service's proxy
    071     * @throws RuntimeException if the service does not exist (this is considered programmer error), or multiple
    072     *                          services directly implement, or extend from, the service interface
    073     * @see org.apache.tapestry5.ioc.annotations.Marker
    074     * @since 5.3
    075     */
    076    <T> T getService(Class<T> serviceInterface, Class<? extends Annotation>... markerTypes);
    077
    078    /**
    079     * Obtains an object indirectly, using the {@link org.apache.tapestry5.ioc.services.MasterObjectProvider} service.
    080     *
    081     * @param objectType         the type of object to be returned
    082     * @param annotationProvider provides access to annotations on the field or parameter for which a value is to
    083     *                           be
    084     *                           obtained, which may be utilized in selecting an appropriate object, use
    085     *                           <strong>null</strong> when annotations are not available (in which case, selection
    086     *                           will
    087     *                           be based only on the object type)
    088     * @param <T>
    089     * @return the requested object
    090     * @see ObjectProvider
    091     */
    092    <T> T getObject(Class<T> objectType, AnnotationProvider annotationProvider);
    093
    094    /**
    095     * Autobuilds a class by finding the public constructor with the most parameters. Services and other resources or
    096     * dependencies will be injected into the parameters of the constructor and into private fields marked with the
    097     * {@link Inject} annotation. There are two cases: constructing a service implementation, and constructing
    098     * an arbitrary object. In the former case, many <em>service resources</em> are also available for injection, not
    099     * just dependencies or objects provided via
    100     * {@link MasterObjectProvider#provide(Class, AnnotationProvider, ObjectLocator, boolean)}.
    101     *
    102     * @param <T>
    103     * @param clazz the type of object to instantiate
    104     * @return the instantiated instance
    105     * @throws RuntimeException if the autobuild fails
    106     * @see MasterObjectProvider
    107     */
    108    <T> T autobuild(Class<T> clazz);
    109
    110    /**
    111     * Preferred version of {@link #autobuild(Class)} that tracks the operation using
    112     * {@link OperationTracker#invoke(String, Invokable)}.
    113     *
    114     * @param <T>
    115     * @param description description used with {@link OperationTracker}
    116     * @param clazz       the type of object to instantiate
    117     * @return the instantiated instance
    118     * @throws RuntimeException if the autobuild fails
    119     * @see MasterObjectProvider
    120     * @since 5.2.0
    121     */
    122    <T> T autobuild(String description, Class<T> clazz);
    123
    124    /**
    125     * Creates a proxy. The proxy will defer invocation of {@link #autobuild(Class)} until
    126     * just-in-time (that is, first method invocation). In a limited number of cases, it is necessary to use such a
    127     * proxy to prevent service construction cycles, particularly when contributing (directly or indirectly) to the
    128     * {@link org.apache.tapestry5.ioc.services.MasterObjectProvider} (which is itself at the heart
    129     * of autobuilding).
    130     * <p/>
    131     * If the class file for the class is a file on the file system (not a file packaged in a JAR), then the proxy will
    132     * <em>autoreload</em>: changing the class file will result in the new class being reloaded and re-instantiated
    133     * (with dependencies).
    134     *
    135     * @param <T>
    136     * @param interfaceClass      the interface implemented by the proxy
    137     * @param implementationClass a concrete class that implements the interface
    138     * @return a proxy
    139     * @see #autobuild(Class)
    140     */
    141    <T> T proxy(Class<T> interfaceClass, Class<? extends T> implementationClass);
    142}