/**
* Reads the content of a file and tries to parse it as JSON into an object.
*
* @param file The file on disk to read from.
* @param classOfValue The class definition that the JSON should be parsed into.
* @return The object stored in the file.
* @throws IOException If anything went wrong during file access.
*/
protected static <E> E readObjectFromDisk(File file, Class<E> classOfValue) throws IOException {
// Validate file.
if (!isReadableFile(file)) {
return null;
}
if (classOfValue == null || classOfValue.equals(Void.class)) {
return null;
}
long length = file.length();
if (length < 0 || length > Integer.MAX_VALUE) {
return null;
}
// Read from disk.
byte[] bytes = new byte[(int) length];
FileInputStream fileInputStream = new FileInputStream(file);
try {
fileInputStream.read(bytes);
} finally {
fileInputStream.close();
}
// Parse JSON to object.
String json = new String(bytes);
E result = JsonParser.fromJson(json, classOfValue);
return result;
}
/**
* Tries to write the value to the disk store. An attempt will be made to parse the value to JSON
* and on success it will be written to a file with the same name as the key. The key will be
* transformed to the file name by calling the <code>toString()</code> method on it (pick your
* keys with great care).
*
* @param file The {@link File} pointing at the desired destination file on disk.
* @param value The value that will be serialized to JSON and saved as a file.
* @throws IOException
*/
protected static void writeObjectToDisk(File file, Object value) throws IOException {
String json = JsonParser.toJson(value);
FileOutputStream fileOutputStream = new FileOutputStream(file);
try {
fileOutputStream.write(json.getBytes());
} finally {
fileOutputStream.close();
}
}