eu.semaine.jms.JMSLogger.java Source code

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Here is the source code for eu.semaine.jms.JMSLogger.java

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/**
 * Copyright (C) 2008 DFKI GmbH. All rights reserved.
 * Use is subject to license terms -- see license.txt.
 */
package eu.semaine.jms;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.JMSException;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.TextMessage;

import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import eu.semaine.components.MessageLogComponent;

/**
 * A relatively lightweight class logging messages to a JMS topic if possible,
 * and to the local log system if the JMS connection fails. All instances of 
 * JMSLogger use the same JMS connection and the same session.
 * @author marc
 *
 */
public class JMSLogger {
    ////////// Static stuff, used by all JMSLoggers ///////////
    private static Connection connection;
    private static Session session;
    private static Map<String, JMSLogger> loggers = new HashMap<String, JMSLogger>();

    static {
        try {
            String jmsUrl = System.getProperty("jms.url", "tcp://localhost:61616");
            String jmsUser = System.getProperty("jms.user", null);
            String jmsPassword = System.getProperty("jms.password", null);
            connection = IOBase.getConnection(jmsUrl, jmsUser, jmsPassword, null);
            session = connection.createSession(false /*not transacted*/, Session.AUTO_ACKNOWLEDGE);
            connection.start();
        } catch (JMSException e) {
            LogFactory.getLog(JMSLogger.class).warn("Cannot set up JMS logger connection and session", e);
        }
    };

    public static JMSLogger getLog(String source) {
        if (!loggers.containsKey(source)) {
            loggers.put(source, new JMSLogger(source));
        }
        return loggers.get(source);

    }

    /////////////// Individual stuff ////////////////
    private enum Level {
        error, warn, info, debug
    };

    private MessageProducer error;
    private MessageProducer warn;
    private MessageProducer info;
    private MessageProducer debug;

    private Log fallbackLogger;

    /**
     * @param topicName
     * @param datatype
     * @param source
     * @throws JMSException
     */
    private JMSLogger(String source) {
        String basename = "semaine.log." + source;
        fallbackLogger = LogFactory.getLog(basename);
        try {
            error = session.createProducer(session.createTopic(basename + ".error"));
            warn = session.createProducer(session.createTopic(basename + ".warn"));
            info = session.createProducer(session.createTopic(basename + ".info"));
            debug = session.createProducer(session.createTopic(basename + ".debug"));
        } catch (JMSException e) {
            fallbackLogger.warn("Cannot set up JMS log connections for " + source + "; will use fallback instead");
        }
    }

    public void error(Object... objects) {
        log(error, Level.error, -1, objects);
    }

    public void warn(Object... objects) {
        log(warn, Level.warn, -1, objects);
    }

    public void info(Object... objects) {
        log(info, Level.info, -1, objects);
    }

    public void debug(Object... objects) {
        log(debug, Level.debug, -1, objects);
    }

    public void error(long usertime, Object... objects) {
        log(error, Level.error, usertime, objects);
    }

    public void warn(long usertime, Object... objects) {
        log(warn, Level.warn, usertime, objects);
    }

    public void info(long usertime, Object... objects) {
        log(info, Level.info, usertime, objects);
    }

    public void debug(long usertime, Object... objects) {
        log(debug, Level.debug, usertime, objects);
    }

    private void log(MessageProducer target, Level level, long usertime, Object... objects) {
        String logMessageText = toLogMessageText(usertime, objects);
        try {
            TextMessage message = session.createTextMessage(logMessageText);
            target.send(message);
        } catch (JMSException e) {
            fallbackLogger.error("problem with JMS logger", e);
            if (level == Level.error) {
                fallbackLogger.error(logMessageText);
            } else if (level == Level.warn) {
                fallbackLogger.warn(logMessageText);
            } else if (level == Level.info) {
                fallbackLogger.warn(logMessageText);
            } else if (level == Level.debug) {
                fallbackLogger.warn(logMessageText);
            } else {
                fallbackLogger.error("problem with fallback logger -- unknown log level: " + level);
                fallbackLogger.info(logMessageText);
            }
        }

    }

    public static String toLogMessageText(Object... objects) {
        return toLogMessageText(-1, objects);
    }

    public static String toLogMessageText(long usertime, Object... objects) {
        StringBuilder builder = new StringBuilder();
        if (usertime >= 0) {
            builder.append("[")
                    .append(new SimpleDateFormat(MessageLogComponent.TIME_FORMAT).format(new Date(usertime)))
                    .append("]");

        }
        for (Object o : objects) {
            if (builder.length() > 0) {
                builder.append(" ");
            }
            if (o instanceof Throwable) {
                Throwable t = (Throwable) o;
                StringWriter sw = new StringWriter();
                t.printStackTrace(new PrintWriter(sw));
                builder.append(sw.toString());
            } else {
                builder.append(o.toString());
            }
        }
        String logMessageText = builder.toString();
        return logMessageText;
    }

    public boolean isDebugEnabled() {
        // in the future, we may be able to use advisory information to know
        // if anyone is listening to this topic
        return true;
    }
}