ServiceEntry.java

/*
 * Beanfabrics Framework Copyright (C) by Michael Karneim, beanfabrics.org
 * Use is subject to license terms. See license.txt.
 */
package org.beanfabrics.context;

/**
 * A {@link ServiceEntry} describes the attributes of a service entry in a
 * specific context. It provides access to the service itself as well as
 * information about the location, the type and the distance.
 * 
 * @author Michael Karneim
 */
public class ServiceEntry {
    private final Context origin;
    private final int distance;
    private final Object service;
    private final Class<?> type;

    /**
     * Constructs a {@link ServiceEntry}.
     * 
     * @param distance the distance is defined as the number of hierarchical
     *            steps between the owner context and the context the service
     *            was originally placed into.
     * @param origin the context the service was originally placed into
     * @param service the service implementation
     * @param type the service type that will be used as the lookup key
     */
    public ServiceEntry(int distance, Context origin, Object service, Class<?> type) {
        super();
        if (type == null) {
            throw new IllegalArgumentException("type==null");
        }
        if (service != null && type.isInstance(service) == false) {
            throw new IllegalArgumentException("service must be instance of " + type.getName() + " but was " + service.getClass().getName());
        }
        this.distance = distance;
        this.origin = origin;
        this.service = service;
        this.type = type;
    }

    /**
     * Returns the context where the service was originally placed into.
     * 
     * @return the context where the service was originally placed into
     */
    public Context getOrigin() {
        return origin;
    }

    /**
     * Returns the distance, where distance is defined as the number of
     * hierarchical steps between the owner context and the context the service
     * was originally placed into.
     * 
     * @return the distance
     */
    public int getDistance() {
        return distance;
    }

    /**
     * Returns the service implementation.
     * 
     * @return the service implementation
     */
    public Object getService() {
        return service;
    }

    public Class<?> getType() {
        return type;
    }
}