Apache Log4j Core Implementation provides the functional components of the logging system. Users are free to create their own plugins and include them in the logging configuration. Apache Log4j Core is a required module to use Apache Log4j.

Bytecode (Java 8) for Apache Log4j Core Implementation is provided in a separate JAR file like log4j-core-2.14.1.jar.

Source Code files for Apache Log4j API are provided in both binary packge like apache-log4j-2.14.1-bin.zip and source package like apache-log4j-2.14.1-src.zip. You can download them at Apache Log4j Website.

You can also browse Source Code files for Apache Log4j Core Implementation 2.14.1 below.

⏎ org/apache/logging/log4j/core/pattern/StyleConverter.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.logging.log4j.core.pattern;

import java.util.Arrays;
import java.util.List;

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.util.Patterns;
import org.apache.logging.log4j.util.PerformanceSensitive;

/**
 * Style pattern converter. Adds ANSI color styling to the result of the enclosed pattern.
 *
 * <p>
 * To disable ANSI output unconditionally, specify an additional option <code>disableAnsi=true</code>, or to
 * disable ANSI output if no console is detected, specify option <code>noConsoleNoAnsi=true</code>.
 * </p>
 */
@Plugin(name = "style", category = PatternConverter.CATEGORY)
@ConverterKeys({ "style" })
@PerformanceSensitive("allocation")
public final class StyleConverter extends LogEventPatternConverter implements AnsiConverter {

    private final List<PatternFormatter> patternFormatters;

    private final boolean noAnsi;

    private final String style;

    private final String defaultStyle;

    /**
     * Constructs the converter.
     *
     * @param patternFormatters
     *            The PatternFormatters to generate the text to manipulate.
     * @param style
     *            The style that should encapsulate the pattern.
     * @param noAnsi
     *            If true, do not output ANSI escape codes.
     */
    private StyleConverter(final List<PatternFormatter> patternFormatters, final String style, final boolean noAnsi) {
        super("style", "style");
        this.patternFormatters = patternFormatters;
        this.style = style;
        this.defaultStyle = AnsiEscape.getDefaultStyle();
        this.noAnsi = noAnsi;
    }

    /**
     * Gets an instance of the class.
     *
     * @param config
     *            The current Configuration.
     * @param options
     *            pattern options, may be null. If first element is "short", only the first line of the throwable will
     *            be formatted.
     * @return instance of class.
     */
    public static StyleConverter newInstance(final Configuration config, final String[] options) {
        if (options == null) {
            return null;
        }
        if (options.length < 2) {
            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 for style converter");
            return null;
        }
        if (options[1] == null) {
            LOGGER.error("No style attributes supplied for style converter");
            return null;
        }
        final PatternParser parser = PatternLayout.createPatternParser(config);
        final List<PatternFormatter> formatters = parser.parse(options[0]);
        final String style = AnsiEscape.createSequence(options[1].split(Patterns.COMMA_SEPARATOR));
        final boolean disableAnsi = Arrays.toString(options).contains(PatternParser.DISABLE_ANSI + "=true");
        final boolean noConsoleNoAnsi = Arrays.toString(options).contains(PatternParser.NO_CONSOLE_NO_ANSI + "=true");
        final boolean hideAnsi = disableAnsi || (noConsoleNoAnsi && System.console() == null);
        return new StyleConverter(formatters, style, hideAnsi);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void format(final LogEvent event, final StringBuilder toAppendTo) {
        int start = 0;
        int end = 0;
        if (!noAnsi) { // use ANSI: set prefix
            start = toAppendTo.length();
            toAppendTo.append(style);
            end = toAppendTo.length();
        }

        //noinspection ForLoopReplaceableByForEach
        for (int i = 0, size = patternFormatters.size(); i <  size; i++) {
            patternFormatters.get(i).format(event, toAppendTo);
        }

        // if we use ANSI we need to add the postfix or erase the unnecessary prefix
        if (!noAnsi) {
            if (toAppendTo.length() == end) {
                toAppendTo.setLength(start); // erase prefix
            } else {
                toAppendTo.append(defaultStyle); // add postfix
            }
        }
    }

    @Override
    public boolean handlesThrowable() {
        for (final PatternFormatter formatter : patternFormatters) {
            if (formatter.handlesThrowable()) {
                return true;
            }
        }
        return false;
    }

    /**
     * Returns a String suitable for debugging.
     *
     * @return a String suitable for debugging.
     */
    @Override
    public String toString() {
        final StringBuilder sb = new StringBuilder();
        sb.append(super.toString());
        sb.append("[style=");
        sb.append(style);
        sb.append(", defaultStyle=");
        sb.append(defaultStyle);
        sb.append(", patternFormatters=");
        sb.append(patternFormatters);
        sb.append(", noAnsi=");
        sb.append(noAnsi);
        sb.append(']');
        return sb.toString();
    }

}

⏎ org/apache/logging/log4j/core/pattern/StyleConverter.java

Or download all of them as a single archive file:

File name: log4j-core-2.14.1-sources.jar
File size: 1281358 bytes
Release date: 2021-03-06
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