src/jsr311-api/src/javax/ws/rs/core/Application.java

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package javax.ws.rs.core;

import java.util.Collections;
import java.util.Set;

/**
 * Defines the components of a JAX-RS application and supplies additional
 * metadata. A JAX-RS application or implementation supplies a concrete
 * subclass of this abstract class.
 *
 * <p>The implementation-created instance of an Application subclass may be
 * injected into resource classes and providers using
 * {@link javax.ws.rs.core.Context}.<p>
 * 
 */
public class Application {
    private static final Set<Object> emptyObjectSet = Collections.emptySet();
    private static final Set<Class<?>> emptyClassSet = Collections.emptySet();
    
    /**
     * Get a set of root resource and provider classes. The default lifecycle
     * for resource class instances is per-request. The default lifecycle for
     * providers is singleton.
     * 
     * <p>Implementations should warn about and ignore classes that do not 
     * conform to the requirements of root resource or provider classes.
     * Implementations should warn about and ignore classes for which
     * {@link #getSingletons()} returns an instance. Implementations MUST
     * NOT modify the returned set.</p>
     * 
     * <p>The default implementation returns an empty set.</p>
     *
     * @return a set of root resource and provider classes. Returning null
     * is equivalent to returning an empty set.
     */
    public Set<Class<?>> getClasses() {
        return emptyClassSet;
    }
    
    /**
     * Get a set of root resource and provider instances. Fields and properties
     * of returned instances are injected with their declared dependencies
     * (see {@link Context}) by the runtime prior to use.
     * 
     * <p>Implementations should warn about and ignore classes that do not
     * conform to the requirements of root resource or provider classes.
     * Implementations should flag an error if the returned set includes
     * more than one instance of the same class. Implementations MUST
     * NOT modify the returned set.</p>
     * 
     * <p>The default implementation returns an empty set.</p>
     * 
     * @return a set of root resource and provider instances. Returning null
     * is equivalent to returning an empty set.
     */
    public Set<Object> getSingletons() {
        return emptyObjectSet;
    }
    
}