entityutils.java

spring的源代码

package org.springframework.samples.petclinic.util;

import java.util.Collection;
import java.util.Iterator;

import org.springframework.orm.ObjectRetrievalFailureException;
import org.springframework.samples.petclinic.Entity;

/**
 * Utility methods for handling entities.
 * Separate from the Entity class mainly because of dependency
 * on the ORM-associated ObjectRetrievalFailureException.
 *
 * @author Juergen Hoeller
 * @since 29.10.2003
 * @see org.springframework.samples.petclinic.Entity
 */
public abstract class EntityUtils {

	/**
	 * Look up the entity of the given class with the given id
	 * in the given collection.
	 * @param entities the collection to search
	 * @param entityClass the entity class to look up
	 * @param entityId the entity id to look up
	 * @return the found entity
	 * @throws ObjectRetrievalFailureException if the entity was not found
	 */
	public static Entity getById(Collection entities, Class entityClass, int entityId)
	    throws ObjectRetrievalFailureException {

		for (Iterator it = entities.iterator(); it.hasNext();) {
			Entity entity = (Entity) it.next();
			if (entity.getId().intValue() == entityId && entityClass.isInstance(entity)) {
				return entity;
			}
		}
		throw new ObjectRetrievalFailureException(entityClass, new Integer(entityId));
	}

}