/**
* Retrieves the hashTable from the file specified by <i>source</i>.
*
* @param source the name of the file from which the hashTable is to be retrieved.
* @pre <i>None</i>
* @post If there is any error ⇒ LocalObjectId.nextId = LocalObjectId.INITIAL_ID and
* |hashTable| = 0 Else the hashTable in the specified file is retrieved and stored in
* hashTable AND LocalObjectId.nextId = |hashTable|
*/
public void restore(String source) {
String fileLocation = DEFAULT_FILE_LOCATION;
if (FILE_LOCATION != null) {
fileLocation = FILE_LOCATION;
}
if (source != null) {
fileLocation = source;
}
try {
ObjectInputStream ois =
new ObjectInputStream(new BufferedInputStream(new FileInputStream(fileLocation)));
int nextId = ois.read();
LocalObjectId.setNextId(nextId);
hashTable = (Hashtable<LocalObjectId, Object>) ois.readObject();
ois.close();
} catch (Exception e) {
LocalObjectId.setNextId(LocalObjectId.INITIAL_ID);
hashTable = new Hashtable<LocalObjectId, Object>();
}
}
/**
* Saves the hashTable in the file specified by the <i>destination</i>. *
*
* @pre destination ≠ null AND location in file system where file is to be created exists AND
* the file location is writable AND every object in the ObjectDB is serializable.
* @post the hashTable has been saved to the file named <i>destination</i> along with the size of
* the hashTable.
*/
public void save(String destination) {
String fileLocation = DEFAULT_FILE_LOCATION;
if (FILE_LOCATION != null) {
fileLocation = FILE_LOCATION;
}
if (destination != null) {
fileLocation = destination;
}
try {
ObjectOutputStream oos =
new ObjectOutputStream(new BufferedOutputStream(new FileOutputStream(fileLocation)));
oos.write(LocalObjectId.getNextId());
oos.writeObject(hashTable);
oos.flush();
oos.close();
} catch (Exception e) {
System.err.println("In communicator.ObjectDB::save(String) -- ERROR could not save ObjectDB");
}
}
/**
* Empties the ObjectDB and sets the next LocalObjectID to the initial LocalObjectId.
*
* @pre <i>None</i>
* @post |hashTable| = 0 AND LocalObjectId.nextId = LocalObjectId.INITIAL_ID
*/
public void clear() {
hashTable.clear();
LocalObjectId.setNextId(LocalObjectId.INITIAL_ID);
}
