/* * @(#)Database.java	1.2 03/01/22 * * Copyright (c) 1999-2003 Sun Microsystems, Inc. All rights reserved.  * PROPRIETARY/CONFIDENTIAL * Use is subject to license terms */package example.stock;import javax.microedition.rms.*;import java.util.*;import java.io.EOFException;/** * <p>This class provides a wrapper class for the  * <code>RecordStore</code> class. * It allows for easier addition and deletion as well as better searching and * updating of records.  The used recordIDs are kept in a <code>Vector</code> * which we use to access the indices of the records.  The last used recordID * is stored at the beginning of the database and when the database is opened, * each recordID up to the last one used is tested to see if a record exists in * that position and a new <code>Vector</code> of used recordIDs * is generated.</p> */public abstract class Database {    /**     * The database storing all the records and the last     * used recordID in position 1     */    protected volatile RecordStore database = null;    /**     * The <code>Vector</code> of used recordIDs that are in the database     */    protected volatile Vector recordIDs = null;    /**     * The last used ID in the database     */    protected int lastID = 1;    /**     * The object used to compare two records and see if they are equal     */    protected RecordComparator rc = null;    /**     * <p>Initializes the database and if it's not a new database, loads the     * recordID of the last record out of the first position in the     * <code>RecordStore</code>.  We have stored it there when we closed the     * database, then checks each ID from 1 to lastID to see if they exist in     * the database and then add the IDs that exist to the recordIDs     * <code>Vector</code></p>     *     * @param fileName The name of the <code>RecordStore</code> to open     * @throws <code>RecordStoreNotFoundException</code> is thrown if the     *         <code>RecordStore</code> indicated with <code>fileName</code>     *         cannot be found     * @throws <code>RecordStoreException</code> is thrown when a general     *         exception occurs in a <code>RecordStore</code> operation     * @throws <code>RecordStoreFullException</code> is thrown when the     *         storage system is is full     */    public void open(String fileName) throws RecordStoreNotFoundException,                                             RecordStoreException,                                             RecordStoreFullException {        database = RecordStore.openRecordStore(fileName, true);        recordIDs = new Vector();        try {            if (database.getNumRecords() != 0) {                try {                    lastID = 			Integer.valueOf(			    new String(database.getRecord(1))).intValue();                    for (int i = 1; i <= lastID; i++) {                        try {                            database.getRecord(i);                            recordIDs.addElement(new Integer(i));                        } catch (RecordStoreException rs) {}                    }                } catch (InvalidRecordIDException iri) {                    throw new RecordStoreException(iri.getMessage());                }            }        } catch (RecordStoreNotOpenException rsno) {            throw new RecordStoreException(rsno.getMessage());        }    }    /**     * <p>Close the database and remove it from persistant      * storage if it is empty</p>     *     * @throws <code>RecordStoreNotOpenException</code> is thrown when trying     *         to close a <code>RecordStore</code> that is not open     * @throws <code>RecordStoreException</code> is thrown when a general     *         exception occurs in a <code>RecordStore</code> operation     */    public void close() throws RecordStoreNotOpenException,                               RecordStoreException {        if (database.getNumRecords() == 0) {            String fileName = database.getName();            database.closeRecordStore();            database.deleteRecordStore(fileName);        } else {            database.closeRecordStore();        }    }    /**     * <p>Remove the database from persistant storage</p>     *     * @param fileName the name of the <code>RecordStore</code> to remove     */    public void cleanUp(String fileName) throws RecordStoreNotFoundException,                                                RecordStoreException {        RecordStore.deleteRecordStore(fileName);        open(fileName);    }    /**     * <p>Add the record to the database<BR>     * Add the recordID to our vector<BR>     * Update the database's last ID counter</p>     *     * @param record The record data to be added to the database     * @throws <code>RecordStoreNotOpenException</code> is thrown when     *         trying to close a <code>RecordStore</code> that is not open     * @throws <code>RecordStoreFullException</code> is thrown when the storage     *         system is is full     * @throws <code>RecordStoreException</code> is thrown when a general     *         exception occurs in a <code>RecordStore</code> operation     */    public synchronized void add(String record)	throws RecordStoreNotOpenException,	RecordStoreFullException,	RecordStoreException {        if (database.getNumRecords() != 0) {            database.addRecord(record.getBytes(), 0, record.getBytes().length);            recordIDs.addElement(new Integer(++lastID));            database.setRecord(1, (String.valueOf(lastID)).getBytes(),                               0, (String.valueOf(lastID)).length());        } else {            recordIDs.addElement(new Integer(++lastID));            database.addRecord((String.valueOf(lastID)).getBytes(),                               0, (String.valueOf(lastID)).length());            try {                database.addRecord(record.getBytes(), 0,				   record.getBytes().length);            } catch (RecordStoreException rs) {                recordIDs.removeElement(new Integer(lastID--));                database.setRecord(1, (String.valueOf(lastID)).getBytes(),                                   0, (String.valueOf(lastID)).length());                throw rs;            }        }    }    /**     * <p>Delete the record from the database and remove that recordID from the     * vector of used recordIDs</p>     *     * @param s The name of the record to delete from the database     * @throws <code>RecordStoreNotOpenException</code> is thrown when trying     *         to close a <code>RecordStore</code> that is not open     * @throws <code>RecordStoreException</code> is thrown when a general     *         exception occurs in a <code>RecordStore</code> operation     */    public synchronized void delete(String s)	throws RecordStoreNotOpenException,	RecordStoreException {        action(s, null, 0);    }    /**     * <p>Find and return a record</p>     *     * @return The record that we're looking for or      * <code>null</code> if not found     * @param s The name of the record to search for     * @throws <code>RecordStoreNotOpenException</code> is thrown when trying     *         to close a <code>RecordStore</code> that is not open     * @throws <code>RecordStoreException</code> is thrown when a general     *         exception occurs in a <code>RecordStore</code> operation     */    public synchronized String search(String s)            throws RecordStoreNotOpenException, RecordStoreException {        return (String) action(s, null, 1);    }    /**     * <p>Update the record with the name <code>s</code> with the data     * in the byte[] array</p>     *     * @param s The name of the record to update     * @param data the new data to update the record with     * @throws <code>RecordStoreNotOpenException</code> is thrown when trying     *         to close a <code>RecordStore</code> that is not open     * @throws <code>RecordStoreFullException</code> is thrown when the storage     *         system is is full     * @throws <code>RecordStoreException</code> is thrown when a general     *         exception occurs in a <code>RecordStore</code> operation     */    public synchronized void update(String s, byte[] data)            throws RecordStoreNotOpenException, RecordStoreFullException,	RecordStoreException {        action(s, data, 2);    }    /**     * <p>Go to the index of the record specified by <code>s</code> and perform     * an action.  Either an update, search or deletion.  This method is for     * code compaction as the process for updating, searching and     * deleting varies only slightly.</p>     *     * @param s The name of the record to perform the action on     * @param data Data to use in the action     * @param action What to do. 0 = delete, 1 = search, 2 = update     * @throws <code>RecordStoreNotOpenException</code> is thrown when trying     *         to close a <code>RecordStore</code> that is not open     * @throws <code>RecordStoreFullException</code> is thrown when the storage     *         system is is full     * @throws <code>RecordStoreException</code> is thrown when a general     *         exception occurs in a <code>RecordStore</code> operation     */    private synchronized Object action(String s, byte[] data, int action)        throws RecordStoreNotOpenException, RecordStoreFullException,	RecordStoreException {        if ((action != 1) && (recordIDs.size() == 0)) {            throw new RecordStoreException();        }        Enumeration IDs = recordIDs.elements();        while (IDs.hasMoreElements()) {            int index = ((Integer) IDs.nextElement()).intValue();            try {                if (rc.compare(database.getRecord(index), s.getBytes())                        == RecordComparator.EQUIVALENT) {                    switch (action) {                    case 0:                        database.deleteRecord(index);                        recordIDs.removeElement(new Integer(index));                        return null;                    case 1:                        return new String(database.getRecord(index));                    case 2:                        database.setRecord(index, data, 0, data.length);                        return null;                    default:                        break;                    }                }            } catch (InvalidRecordIDException iri) {                throw new RecordStoreException(iri.getMessage());            }        }        return null;    }    /**     * <p>Return the number of records in the database</p>     *     * @return the number of records in the database     * @throws <code>RecordStoreNotOpenException</code> is thrown when trying     *         to close a <code>RecordStore</code> that is not open     */    public int getNumRecords() throws RecordStoreNotOpenException {        return database.getNumRecords();    }}