openjpa-lib/src/main/java/org/apache/openjpa/lib/log/LogOutputStream.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.openjpa.lib.log;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.StringTokenizer;

import org.apache.openjpa.lib.util.J2DoPrivHelper;

/**
 * Many standard components log to {@link OutputStream}s.
 * This wrapper class extends the {@link ByteArrayOutputStream}
 * class and writes all given data to an underlying {@link Log} instance
 * whenever it is flushed and the internally held byte array contains a newline.
 *
 * @author Abe White, Marc Prud'hommeaux
 */
public class LogOutputStream extends ByteArrayOutputStream {

    private static final String _sep = J2DoPrivHelper.getLineSeparator();

    private final int _level;
    private final Log _log;

    /**
     * Constructor.
     *
     * @param log the log to log to
     * @param level the level to log at
     */
    public LogOutputStream(Log log, int level) {
        _log = log;
        _level = level;
    }

    public void flush() throws IOException {
        super.flush();
        byte[] bytes = toByteArray();
        if (bytes.length == 0)
            return;

        String msg = new String(bytes);
        if (msg.indexOf(_sep) != -1) {
            // break up the message based on the line separator; this
            // may be because the flushed buffer contains mutliple lines
            for (StringTokenizer tok = new StringTokenizer(msg, _sep);
                tok.hasMoreTokens();) {
                String next = tok.nextToken();
                log(next);
            }

            // clear the internally held byte array
            reset();
        }
    }

    private void log(String msg) {
        switch (_level) {
            case Log.TRACE:
                _log.trace(msg);
                break;
            case Log.INFO:
                _log.info(msg);
                break;
            case Log.WARN:
                _log.warn(msg);
                break;
            case Log.ERROR:
                _log.error(msg);
                break;
            case Log.FATAL:
                _log.fatal(msg);
                break;
        }
    }
}