ColorConverter Class — spring-boot Architecture

Source Code

core/spring-boot/src/main/java/org/springframework/boot/logging/log4j2/ColorConverter.java lines 51–138

@Plugin(name = "color", category = PatternConverter.CATEGORY)
@ConverterKeys({ "clr", "color" })
public final class ColorConverter extends LogEventPatternConverter {

	private static final Map<String, AnsiElement> ELEMENTS;

	static {
		Map<String, AnsiElement> ansiElements = new HashMap<>();
		Arrays.stream(AnsiColor.values())
			.filter((color) -> color != AnsiColor.DEFAULT)
			.forEach((color) -> ansiElements.put(color.name().toLowerCase(Locale.ROOT), color));
		ansiElements.put("faint", AnsiStyle.FAINT);
		ELEMENTS = Collections.unmodifiableMap(ansiElements);
	}

	private static final Map<Integer, AnsiElement> LEVELS;

	static {
		Map<Integer, AnsiElement> ansiLevels = new HashMap<>();
		ansiLevels.put(Level.FATAL.intLevel(), AnsiColor.RED);
		ansiLevels.put(Level.ERROR.intLevel(), AnsiColor.RED);
		ansiLevels.put(Level.WARN.intLevel(), AnsiColor.YELLOW);
		LEVELS = Collections.unmodifiableMap(ansiLevels);
	}

	private final List<PatternFormatter> formatters;

	private final @Nullable AnsiElement styling;

	private ColorConverter(List<PatternFormatter> formatters, @Nullable AnsiElement styling) {
		super("style", "style");
		this.formatters = formatters;
		this.styling = styling;
	}

	@Override
	public boolean handlesThrowable() {
		for (PatternFormatter formatter : this.formatters) {
			if (formatter.handlesThrowable()) {
				return true;
			}
		}
		return super.handlesThrowable();
	}

	@Override
	public void format(LogEvent event, StringBuilder toAppendTo) {
		StringBuilder buf = new StringBuilder();
		for (PatternFormatter formatter : this.formatters) {
			formatter.format(event, buf);
		}
		if (!buf.isEmpty()) {
			AnsiElement element = this.styling;
			if (element == null) {
				// Assume highlighting
				element = LEVELS.get(event.getLevel().intLevel());
				element = (element != null) ? element : AnsiColor.GREEN;
			}
			appendAnsiString(toAppendTo, buf.toString(), element);
		}
	}

	protected void appendAnsiString(StringBuilder toAppendTo, String in, AnsiElement element) {
		toAppendTo.append(AnsiOutput.toString(element, in));
	}

	/**
	 * Creates a new instance of the class. Required by Log4J2.
	 * @param config the configuration
	 * @param options the options
	 * @return a new instance, or {@code null} if the options are invalid
	 */
	public static @Nullable ColorConverter newInstance(@Nullable Configuration config, @Nullable String[] options) {
		if (options.length < 1) {
			LOGGER.error("Incorrect number of options on style. Expected at least 1, received {}", options.length);
			return null;
		}
		if (options[0] == null) {
			LOGGER.error("No pattern supplied on style");
			return null;
		}
		PatternParser parser = PatternLayout.createPatternParser(config);
		List<PatternFormatter> formatters = parser.parse(options[0]);
		AnsiElement element = (options.length != 1) ? ELEMENTS.get(options[1]) : null;
		return new ColorConverter(formatters, element);
	}

}