ColorConverter.java

/*
 * Copyright 2012-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot.logging.log4j2;

import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.layout.PatternLayout;
import org.apache.logging.log4j.core.pattern.ConverterKeys;
import org.apache.logging.log4j.core.pattern.LogEventPatternConverter;
import org.apache.logging.log4j.core.pattern.PatternConverter;
import org.apache.logging.log4j.core.pattern.PatternFormatter;
import org.apache.logging.log4j.core.pattern.PatternParser;

import org.springframework.boot.ansi.AnsiColor;
import org.springframework.boot.ansi.AnsiElement;
import org.springframework.boot.ansi.AnsiOutput;
import org.springframework.boot.ansi.AnsiStyle;

/**
 * Log4j2 {@link LogEventPatternConverter} colors output using the {@link AnsiOutput}
 * class. A single option 'styling' can be provided to the converter, or if not specified
 * color styling will be picked based on the logging level.
 *
 * @author Vladimir Tsanev
 * @since 1.3.0
 */
@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> elements = new HashMap<>();
		elements.put("faint", AnsiStyle.FAINT);
		elements.put("red", AnsiColor.RED);
		elements.put("green", AnsiColor.GREEN);
		elements.put("yellow", AnsiColor.YELLOW);
		elements.put("blue", AnsiColor.BLUE);
		elements.put("magenta", AnsiColor.MAGENTA);
		elements.put("cyan", AnsiColor.CYAN);
		ELEMENTS = Collections.unmodifiableMap(elements);
	}

	private static final Map<Integer, AnsiElement> LEVELS;

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

	private final List<PatternFormatter> formatters;

	private final AnsiElement styling;

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

	/**
	 * 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 ColorConverter newInstance(Configuration config, 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 ? null : ELEMENTS.get(options[1]));
		return new ColorConverter(formatters, element);
	}

	@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.length() > 0) {
			AnsiElement element = this.styling;
			if (element == null) {
				// Assume highlighting
				element = LEVELS.get(event.getLevel().intLevel());
				element = (element == null ? AnsiColor.GREEN : element);
			}
			appendAnsiString(toAppendTo, buf.toString(), element);
		}
	}

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

}