private void appendTo(StringBuilder aText, Object aField, String aAppend) {
if (Util.textHasContent(Util.format(aField))) {
aText.append(Util.format(aField));
} else {
aText.append(NULL);
}
aText.append(aAppend);
}
private static void parseLine(String aLine) throws InvalidInputException {
Scanner scanner = new Scanner(aLine);
// note how the quoting is needed here, since '|' is a special character in
// regular expressions :
scanner.useDelimiter(Pattern.quote(DELIMITER));
scanner.useLocale(Locale.US);
if (scanner.hasNext()) {
String title = scanner.next();
Date viewed = Util.parseDate(maybeNull(scanner.next()), "Date Viewed");
BigDecimal rating = Util.parseBigDecimal(maybeNull(scanner.next()), "Rating");
String comment = maybeNull(scanner.next());
Movie movie = new Movie(nextId().toString(), title, viewed, rating, comment);
fTable.put(movie.getId(), movie);
}
scanner.close();
}
private static void readInMovieFileUponStartup() {
Path moviesPath = Paths.get(getMovieFileName());
fLogger.fine("Reading movies from :" + moviesPath);
String line = "";
try (Scanner scanner = new Scanner(moviesPath, ENCODING.name())) {
while (scanner.hasNextLine()) {
line = scanner.nextLine();
if (Util.textHasContent(line)) {
parseLine(line);
}
}
} catch (FileNotFoundException ex) {
fLogger.config("Movies file not present. Will be created when the app closes.");
} catch (InvalidInputException ex) {
fLogger.severe("Movies file: date-viewed field not in expected format: " + line);
} catch (NoSuchElementException ex) {
fLogger.severe("Movies file: Not in expected format: " + line);
} catch (IOException ex) {
fLogger.severe("Unable to access the movies file.");
}
}
/**
* Data Access Object (DAO) for {@link Movie} objects.
*
* <p>Implements persistence for movie information. This class uses a simple text file called
* <tt>movie_list_for_<<em>user name</em>>.txt</tt>, stored locally, in the application's home
* directory. Each logged in user gets their own list. Each logged in user can see their own list,
* but they cannot see anyone else's list.
*
* <p>The format of the file is specific to this application. The file should not be edited directly
* by an end user, in case the format is violated.
*
* <p>Upon startup, all records in the data-store are read into memory. Edits are performed
* initially only in memory. When the application shuts down, then the updated data store is written
* back to the disk, for use during the next launch of the application.
*/
public final class MovieDAO {
/**
* Save all data to a text file. Must be called explicitly when the app shuts down, in order to
* save all edits.
*/
public void shutdown() {
fLogger.fine("Saving all movie records to file.");
String fileContents = buildFileContents();
writeStringToFile(fileContents);
}
/** Add a new {@link Movie}. */
void add(Movie aMovie) {
String id = nextId();
aMovie.setId(id.toString());
fTable.put(id, aMovie);
}
/** Change an existing {@link Movie}. */
void change(Movie aMovie) {
fTable.put(aMovie.getId(), aMovie);
}
/**
* List all {@link Movie}s. Order is the natural order of the {@link Movie} class (descending
* date, then title).
*/
List<Movie> list() {
List<Movie> result = new ArrayList<>(fTable.values());
Collections.sort(result);
return result;
}
/** Delete an existing {@link Movie}, given the movie id. */
void delete(String aMovieId) {
fTable.remove(aMovieId);
}
// PRIVATE
private static final Map<String, Movie> fTable = new LinkedHashMap<>();
private static int fNextId = 0;
private static final String MOVIES_FILE_NAME = "movie_list_for_";
private static final String DELIMITER = "|";
private static final String NULL = "NULL";
private static final Logger fLogger = Util.getLogger(MovieDAO.class);
private static final Charset ENCODING = StandardCharsets.UTF_8;
static {
readInMovieFileUponStartup();
fLogger.config("Number of movies read in from file: " + fTable.size());
}
private static void readInMovieFileUponStartup() {
Path moviesPath = Paths.get(getMovieFileName());
fLogger.fine("Reading movies from :" + moviesPath);
String line = "";
try (Scanner scanner = new Scanner(moviesPath, ENCODING.name())) {
while (scanner.hasNextLine()) {
line = scanner.nextLine();
if (Util.textHasContent(line)) {
parseLine(line);
}
}
} catch (FileNotFoundException ex) {
fLogger.config("Movies file not present. Will be created when the app closes.");
} catch (InvalidInputException ex) {
fLogger.severe("Movies file: date-viewed field not in expected format: " + line);
} catch (NoSuchElementException ex) {
fLogger.severe("Movies file: Not in expected format: " + line);
} catch (IOException ex) {
fLogger.severe("Unable to access the movies file.");
}
}
private static void parseLine(String aLine) throws InvalidInputException {
Scanner scanner = new Scanner(aLine);
// note how the quoting is needed here, since '|' is a special character in
// regular expressions :
scanner.useDelimiter(Pattern.quote(DELIMITER));
scanner.useLocale(Locale.US);
if (scanner.hasNext()) {
String title = scanner.next();
Date viewed = Util.parseDate(maybeNull(scanner.next()), "Date Viewed");
BigDecimal rating = Util.parseBigDecimal(maybeNull(scanner.next()), "Rating");
String comment = maybeNull(scanner.next());
Movie movie = new Movie(nextId().toString(), title, viewed, rating, comment);
fTable.put(movie.getId(), movie);
}
scanner.close();
}
private static String nextId() {
++fNextId;
return String.valueOf(fNextId);
}
private void appendTo(StringBuilder aText, Object aField, String aAppend) {
if (Util.textHasContent(Util.format(aField))) {
aText.append(Util.format(aField));
} else {
aText.append(NULL);
}
aText.append(aAppend);
}
private static String maybeNull(String aText) {
return NULL.equals(aText) ? null : aText;
}
private static String getMovieFileName() {
return MOVIES_FILE_NAME
+ MainWindow.getInstance().getUserName().toLowerCase(Locale.ENGLISH)
+ ".txt";
}
/** Create a string, holding all movie records. */
private String buildFileContents() {
String NEW_LINE = System.getProperty("line.separator");
StringBuilder result = new StringBuilder();
for (Movie movie : fTable.values()) {
appendTo(result, movie.getTitle(), DELIMITER);
appendTo(result, movie.getDateViewed(), DELIMITER);
appendTo(result, movie.getRating(), DELIMITER);
appendTo(result, movie.getComment(), NEW_LINE);
}
return result.toString();
}
/** Write string containing all movie records to a file - overwrite the whole file. */
private void writeStringToFile(String aFileContents) {
Path moviesPath = Paths.get(getMovieFileName());
fLogger.fine("Writing movies to: " + moviesPath);
try (BufferedWriter writer = Files.newBufferedWriter(moviesPath, ENCODING)) {
writer.write(aFileContents);
} catch (FileNotFoundException ex) {
fLogger.severe("Cannot find movies text file.");
} catch (IOException ex) {
fLogger.severe("Problem while saving movies text file.");
}
}
}