storageadapter.java

一个在线学习系统的服务端SERVLET程序

package eols.storage.base;

import java.util.List;

/**
 * An adapter class which implements part of the functionalities
 * of the storage interface, <code>IStorage</code>.
 *
 * <p>
 * It is mainly used to provide a default implementation of some
 * methods declared in the interface, like <code>java.awt.event.MouseAdapter<code>.
 * </p>
 *
 * <p>
 * In this default implementation, whether the operation on a
 * specific record is successful is not checked.
 * </p>
 *
 * @author Fasheng Qiu
 * @since 11/01/2007
 * @see {@link eols.storage.base.IStorage}
 */
public abstract class StorageAdapter implements IStorage {

        /* The directory where the data file locates */
        public static String dataPath = "";

	/**
	 * Add a list of new records into the external storage file.
	 * NOTE that, in the default implementation, whether the operation
	 * on a specific record is successful is not checked.
	 *
	 * @param records The records to add into the external storage
	 * @return Whether the operation is successful. True will be returned
	 *         if the record list is empty or null.
	 */
	public boolean addRecords(List records){

		if (records == null || records.isEmpty())
			return true;

		for (int i = 0; i < records.size(); i++) {
			if (records.get(i) == null)
				continue;
			addRecord(records.get(i));
		}

		return true;

	}


	/**
	 * Update a list of records in the external storage file.
	 * NOTE that, in the default implementation, whether the operation
	 * on a specific record is successful is not checked.
	 *
	 * <p>
	 * If either the indicator list or the record list is null or
	 * empty, true will be returned.
	 * <p>
	 * <p>
	 * If the size of the two lists is not the same, false will be returned
	 * since the parameters are not prepared well
	 * </p>
	 *
	 * @param indicatorList	The list of identifiers of the records
	 * 						to be updated.
	 * @param records The records to be updated.
	 * 				  Each record has a corresponding indicator which
	 * 				  is stored in the indicatorList.
	 * @return Whether the operation is successful
	 */
	public boolean updateRecords(List indicatorList, List records){

		if (indicatorList == null || indicatorList.isEmpty())
			return true;
		if (records == null || records.isEmpty())
			return true;
		if (indicatorList.size() != records.size())
			return false;

		for (int i = 0; i < records.size(); i++) {
			if (indicatorList.get(i) == null ||
				records.get(i) == null)
				continue;
			updateRecord(indicatorList.get(i), records.get(i));
		}

		return true;
	}

	/**
	 * Delete a list of records in the external storage file.
	 * NOTE that, in the default implementation, whether the operation
	 * on a specific record is successful is not checked.
	 *
	 * @param indicatorList	The list of identifiers of the records
	 * 						to be deleted.
	 * @return Whether the operation is successful
	 */
	public boolean deleteRecords(List indicatorList){

		if (indicatorList == null || indicatorList.isEmpty())
			return true;

		for (int i = 0; i < indicatorList.size(); i++) {
			if (indicatorList.get(i) == null)
				continue;
			deleteRecord(indicatorList.get(i));
		}

		return true;

	}

}