log4j-api/src/main/java/org/apache/logging/log4j/util/LowLevelLogUtil.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.util;

import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.util.Objects;

/**
 * PrintWriter-based logging utility for classes too low level to use {@link org.apache.logging.log4j.status.StatusLogger}.
 * Such classes cannot use StatusLogger as StatusLogger or {@link org.apache.logging.log4j.simple.SimpleLogger} depends
 * on them for initialization. Other framework classes should stick to using StatusLogger.
 *
 * @since 2.6
 */
final class LowLevelLogUtil {

    private static PrintWriter writer = new PrintWriter(System.err, true);

    /**
     * Logs the given message.
     * 
     * @param message the message to log
     * @since 2.9.2
     */
    public static void log(final String message) {
        if (message != null) {
            writer.println(message);
        }
    }

    public static void logException(final Throwable exception) {
        if (exception != null) {
            exception.printStackTrace(writer);
        }
    }

    public static void logException(final String message, final Throwable exception) {
        log(message);
        logException(exception);
    }

    /**
     * Sets the underlying OutputStream where exceptions are printed to.
     *
     * @param out the OutputStream to log to
     */
    public static void setOutputStream(final OutputStream out) {
        LowLevelLogUtil.writer = new PrintWriter(Objects.requireNonNull(out), true);
    }

    /**
     * Sets the underlying Writer where exceptions are printed to.
     *
     * @param writer the Writer to log to
     */
    public static void setWriter(final Writer writer) {
        LowLevelLogUtil.writer = new PrintWriter(Objects.requireNonNull(writer), true);
    }

    private LowLevelLogUtil() {
    }
}