org.webcurator.core.harvester.util.AlertLogger.java Source code

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Here is the source code for org.webcurator.core.harvester.util.AlertLogger.java

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/*
 *  Copyright 2006 The National Library of New Zealand
 *
 *  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 org.webcurator.core.harvester.util;

import java.io.File;
import java.io.FileWriter;
import java.util.Enumeration;
import java.util.Vector;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.archive.io.SinkHandlerLogRecord;

/**
 * The AlertLogger is responsible for writing a harvesters alerts to a log file
 * in the directory with the other Heritrix logs.
 * 
 * Note: There is a problem with this as Heritrix does not currently identify the 
 * Job that generated the alert and there is single alert logger for all the Heritrix
 * instances.
 *  
 * @author nwaight
 */
public class AlertLogger {
    /** used to write the alert log file. */
    private FileWriter fw = null;
    /** the loger. */
    public static final Log log = LogFactory.getLog(AlertLogger.class);

    /** 
     * Constructor taking the jobs log directory and the alert file name.
     * @param aParent the harvest job's log directory
     * @param aFileName the alert log name
     */
    public AlertLogger(File aParent, String aFileName) {
        try {
            File file = new File(aParent, aFileName);
            if (!file.exists()) {
                file.createNewFile();
            }

            fw = new FileWriter(file);
        } catch (Exception e) {
            if (log.isErrorEnabled()) {
                log.error("Failed to create the AlertLogger " + e.getMessage(), e);
            }
            fw = null;
        }
    }

    /**
     * Write the alerts provided in the vector to the log file.
     * @param aAlerts the list of alerts to log
     */
    public void writeAlerts(Vector aAlerts) {
        if (null == fw) {
            if (log.isErrorEnabled()) {
                log.error("Attempting to use an invalid AlertLogger");
            }
            return;
        }

        try {
            SinkHandlerLogRecord alert;
            Enumeration e = aAlerts.elements();
            while (e.hasMoreElements()) {
                alert = (SinkHandlerLogRecord) e.nextElement();
                fw.write(alert.getLevel() + " " + alert.getCreationTime() + " " + alert.getMessage() + " "
                        + alert.getSequenceNumber() + "\n");
            }

            fw.flush();
        } catch (Exception e) {
            if (log.isWarnEnabled()) {
                log.warn("Failed to log alerts. " + e.getMessage(), e);
            }
        }
    }

    /**
     * Close the log file.
     */
    public void close() {
        try {
            if (fw != null) {
                fw.close();
            }
            fw = null;
        } catch (Exception e) {
            if (log.isWarnEnabled()) {
                log.warn("Failed to close the alerts log file. " + e.getMessage(), e);
            }
        }
    }

    /**
     * Attempt to close the log file when the object is garbage collected.
     */
    protected void finalize() {
        close();
    }
}