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/util/StringBuilderWriter.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.util;

import java.io.Serializable;
import java.io.Writer;

/**
 * {@link Writer} implementation that outputs to a {@link StringBuilder}.
 * <p>
 * <strong>NOTE:</strong> This implementation, as an alternative to
 * <code>java.io.StringWriter</code>, provides an <i>un-synchronized</i>
 * (i.e. for use in a single thread) implementation for better performance.
 * For safe usage with multiple {@link Thread}s then
 * <code>java.io.StringWriter</code> should be used.
 *
 * <h3>History</h3>
 * <ol>
 * <li>Copied from Apache Commons IO revision 1681000.</li>
 * <li>Pick up Javadoc updates from revision 1722253.</li>
 * <ol>
 */
public class StringBuilderWriter extends Writer implements Serializable {

    private static final long serialVersionUID = -146927496096066153L;
    private final StringBuilder builder;

    /**
     * Constructs a new {@link StringBuilder} instance with default capacity.
     */
    public StringBuilderWriter() {
        this.builder = new StringBuilder();
    }

    /**
     * Constructs a new {@link StringBuilder} instance with the specified capacity.
     *
     * @param capacity The initial capacity of the underlying {@link StringBuilder}
     */
    public StringBuilderWriter(final int capacity) {
        this.builder = new StringBuilder(capacity);
    }

    /**
     * Constructs a new instance with the specified {@link StringBuilder}.
     *
     * <p>If {@code builder} is null a new instance with default capacity will be created.</p>
     *
     * @param builder The String builder. May be null.
     */
    public StringBuilderWriter(final StringBuilder builder) {
        this.builder = builder != null ? builder : new StringBuilder();
    }

    /**
     * Appends a single character to this Writer.
     *
     * @param value The character to append
     * @return This writer instance
     */
    @Override
    public Writer append(final char value) {
        builder.append(value);
        return this;
    }

    /**
     * Appends a character sequence to this Writer.
     *
     * @param value The character to append
     * @return This writer instance
     */
    @Override
    public Writer append(final CharSequence value) {
        builder.append(value);
        return this;
    }

    /**
     * Appends a portion of a character sequence to the {@link StringBuilder}.
     *
     * @param value The character to append
     * @param start The index of the first character
     * @param end The index of the last character + 1
     * @return This writer instance
     */
    @Override
    public Writer append(final CharSequence value, final int start, final int end) {
        builder.append(value, start, end);
        return this;
    }

    /**
     * Closing this writer has no effect.
     */
    @Override
    public void close() {
        // no-op
    }

    /**
     * Flushing this writer has no effect.
     */
    @Override
    public void flush() {
        // no-op
    }


    /**
     * Writes a String to the {@link StringBuilder}.
     *
     * @param value The value to write
     */
    @Override
    public void write(final String value) {
        if (value != null) {
            builder.append(value);
        }
    }

    /**
     * Writes a portion of a character array to the {@link StringBuilder}.
     *
     * @param value The value to write
     * @param offset The index of the first character
     * @param length The number of characters to write
     */
    @Override
    public void write(final char[] value, final int offset, final int length) {
        if (value != null) {
            builder.append(value, offset, length);
        }
    }

    /**
     * Returns the underlying builder.
     *
     * @return The underlying builder
     */
    public StringBuilder getBuilder() {
        return builder;
    }

    /**
     * Returns {@link StringBuilder#toString()}.
     *
     * @return The contents of the String builder.
     */
    @Override
    public String toString() {
        return builder.toString();
    }
}

⏎ org/apache/logging/log4j/core/util/StringBuilderWriter.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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