com.mgmtp.jfunk.common.cli.LoggingStreamConsumer.java Source code

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Here is the source code for com.mgmtp.jfunk.common.cli.LoggingStreamConsumer.java

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/*
 * Copyright (c) 2015 mgm technology partners GmbH
 *
 * 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 com.mgmtp.jfunk.common.cli;

import javax.annotation.concurrent.ThreadSafe;

import org.apache.commons.lang3.StringUtils;
import org.codehaus.plexus.util.cli.StreamConsumer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * {@link StreamConsumer} for capturing and logging consumed lines.
 * 
 * @author rnaegele
 * @author sherold
 * @since 3.1.0
 */
@ThreadSafe
public final class LoggingStreamConsumer implements StreamConsumer {
    private static final String LINE_SEPARATOR = System.getProperty("line.separator");

    private final Logger logger;
    private final boolean error;
    private final String logMessagePrefix;

    // StringBuffer is used for thread safety!
    private final StringBuffer sb = new StringBuffer(200);

    /**
     * @param loggerName
     *            the name of the logger to use (passed to {@link LoggerFactory#getLogger(String)});
     *            if {@code null} this class' name is used
     * @param logMessagePrefix
     *            if non-{@code null} consumed lines are prefix with this string
     * @param error
     *            specifies whether info or error level is used for logging
     */
    public LoggingStreamConsumer(final String loggerName, final String logMessagePrefix, final boolean error) {
        this.logger = LoggerFactory.getLogger(StringUtils.defaultString(loggerName, getClass().getName()));
        this.logMessagePrefix = logMessagePrefix;
        this.error = error;
    }

    /**
     * {@inheritDoc} Adds each line to an internal {@link StringBuffer} whose contents may be
     * retrieved in {@link #getOutput()} and logs each line applying a non-null
     * {@code logMessagePrefix} using error or info level depending on the {@code error} parameter
     * passed in the constructor.
     */
    @Override
    public void consumeLine(final String line) {
        sb.append(line).append(LINE_SEPARATOR);

        String logMessage = logMessagePrefix != null ? logMessagePrefix + line : line;
        if (error) {
            logger.error(logMessage);
        } else {
            logger.info(logMessage);
        }
    }

    /**
     * Returns the contents of the internal {@link StringBuffer}. Does not reset the
     * {@link StringBuffer}.
     * 
     * @return the output as a string
     */
    public String getOutput() {
        return sb.toString();
    }
}