FileHint Class — spring-boot Architecture

Source Code

core/spring-boot/src/main/java/org/springframework/boot/context/config/FileHint.java lines 34–188

final class FileHint {

	private static final FileHint NONE = new FileHint(Collections.emptyMap());

	private final Map<String, String> attributes;

	private FileHint(Map<String, String> attributes) {
		this.attributes = attributes;
	}

	/**
	 * Return {@code true} if the hint is present.
	 * @return if the hint is present
	 */
	boolean isPresent() {
		return getExtension() != null || getEncoding() != null;
	}

	/**
	 * Returns the extension.
	 * @return the extension
	 */
	@Nullable String getExtension() {
		String extension = this.attributes.get("extension");
		if (extension == null) {
			return null;
		}
		if (!extension.startsWith(".")) {
			return null;
		}
		return extension;
	}

	/**
	 * Return the extension from the hint or return the {@code fallback} if the extension
	 * is not present.
	 * @param fallback the fallback extension
	 * @return the extension either from the hint or fallback
	 */
	String getExtensionOrElse(String fallback) {
		String extension = getExtension();
		return (extension != null) ? extension : fallback;
	}

	/**
	 * Returns the encoding.
	 * @return the encoding
	 */
	@Nullable String getEncoding() {
		return this.attributes.get("encoding");
	}

	/**
	 * Returns the encoding as a {@link Charset}.
	 * @return the encoding as a {@link Charset}
	 */
	@Nullable Charset getEncodingAsCharset() {
		String encoding = getEncoding();
		return (encoding != null) ? Charset.forName(encoding) : null;
	}

	@Override
	public String toString() {
		return "FileHint{attributes=" + this.attributes + '}';
	}

	/**
	 * Return the {@link FileHint} from the given value.
	 * @param value the source value
	 * @return the {@link FileHint}
	 */
	static FileHint from(String value) {
		if (!hasBrackets(value)) {
			return NONE;
		}
		List<String> betweenBrackets = findBetweenBrackets(value);
		Map<String, String> attributes = new HashMap<>();
		for (String entry : betweenBrackets) {
			String cleaned = entry.trim();
			if (cleaned.isEmpty()) {
				continue;
			}
			int equals = cleaned.indexOf('=');
			if (equals == -1) {
				attributes.put("extension", cleaned);
			}
			else {
				attributes.put(cleaned.substring(0, equals).trim(), cleaned.substring(equals + 1).trim());
			}
		}
		return new FileHint(Collections.unmodifiableMap(attributes));
	}

	private static List<String> findBetweenBrackets(String value) {
		List<String> collected = new ArrayList<>();
		StringBuilder buffer = new StringBuilder();
		int brackets = 0;
		for (int i = 0; i < value.length(); i++) {
			char c = value.charAt(i);
			if (c == '[') {
				if (brackets > 0) {
					buffer.append(c);
				}
				brackets++;
			}
			else if (c == ']') {
				brackets--;
				if (brackets > 0) {
					buffer.append(c);
				}
				else if (brackets == 0 && !buffer.isEmpty()) {
					collected.add(buffer.toString());
					buffer.setLength(0);
				}
			}
			else if (brackets > 0) {
				buffer.append(c);
			}
		}
		return collected;
	}

	/**
	 * Remove any hint from the given value.
	 * @param value the source value
	 * @return the value without any hint
	 */
	static String removeFrom(String value) {
		if (!hasBrackets(value)) {
			return value;
		}
		StringBuilder result = new StringBuilder();
		int brackets = 0;
		for (int i = 0; i < value.length(); i++) {
			char c = value.charAt(i);
			if (c == '[') {
				brackets++;
				continue;
			}
			if (c == ']') {
				brackets--;
				continue;
			}
			if (brackets <= 0) {
				result.append(c);
			}
		}
		return result.toString();
	}

	private static boolean hasBrackets(String value) {
		return value.indexOf('[') != -1 && value.indexOf(']') != -1;
	}

}