jlibusb/src/main/java/ch/ntb/usb/logger/LogUtil.java

/* 
 * Java libusb wrapper
 * Copyright (c) 2005-2006 Andreas Schläpfer <spandi at users.sourceforge.net>
 *
 * http://libusbjava.sourceforge.net
 * This library is covered by the LGPL, read LGPL.txt for details.
 */
package ch.ntb.usb.logger;

import java.io.InputStream;
import java.util.Properties;
import java.util.logging.ConsoleHandler;
import java.util.logging.Handler;
import java.util.logging.Level;
import java.util.logging.LogManager;
import java.util.logging.Logger;

public class LogUtil {

    // debug this class
    private static final boolean debugLogUtil = false;

    private static final String PLUGIN_ID = "ch.ntb.usb";
    private static final String PROPERTIES_FILE = ".configure";
    private static final String LOGGER_WARNING = "Warning in class "
            + LogUtil.class.getName()
            + ": could not load the logger properties file " + PROPERTIES_FILE;

    private static boolean debugEnabled;

    static {
        createLoggersFromProperties();
    }

    private static void debugMsg(String method, String message) {
        if (debugLogUtil) {
            System.out.println(method + ": " + message);
        }
    }

    public static void setLevel(Logger logger, Level loglevel) {
        Handler[] h = logger.getHandlers();
        for (int i = 0; i < h.length; i++) {
            System.out.println("setLevel " + loglevel.toString());
            h[i].setLevel(loglevel);
        }
        logger.setLevel(loglevel);
    }

    public static Logger getLogger(String name) {
        debugMsg("getLogger", name);
        LogManager manager = LogManager.getLogManager();
        // check if logger is already registered
        Logger logger = manager.getLogger(name);
        if (logger == null) {
            logger = Logger.getLogger(name);
            setLevel(logger, Level.OFF);
            manager.addLogger(logger);
            debugMsg("getLogger", "creating new logger");
        }
        if (logger.getLevel() == null) {
            debugMsg("getLogger", "level == null -> setLevel to OFF ");
            setLevel(logger, Level.OFF);
        }
        debugMsg("getLogger", "logLevel " + logger.getLevel().getName());
        return logger;
    }

    private static void initLevel(Logger logger, Level loglevel) {
        Handler[] h = logger.getHandlers();
        for (int i = 0; i < h.length; i++) {
            logger.removeHandler(h[i]);
        }
        Handler console = new ConsoleHandler();
        console.setLevel(loglevel);
        logger.addHandler(console);
        logger.setLevel(loglevel);
        logger.setUseParentHandlers(false);
    }

    private static void createLoggersFromProperties() {
        try {
            debugMsg(LogUtil.class.getName(), "createLoggersFromProperties");
            InputStream is = LogUtil.class.getClassLoader()
                    .getResourceAsStream(PROPERTIES_FILE);
            if (is == null) {
                System.err.println(LOGGER_WARNING);
            } else {
                Properties prop = new Properties();
                prop.load(is);
                debugMsg("createLoggersFromProperties",
                        "properties file loaded: " + PROPERTIES_FILE);
                debugMsg("createLoggersFromProperties", "file content:\n"
                        + prop.toString());
                // get global debug enable flag
                debugEnabled = Boolean.parseBoolean(prop.getProperty(PLUGIN_ID
                        + "/debug"));
                debugMsg("createLoggersFromProperties", "debuging enabled: "
                        + debugEnabled);
                // get and configure loggers
                boolean moreLoggers = true;
                int loggerCount = 0;
                while (moreLoggers) {
                    String loggerProp = prop.getProperty(PLUGIN_ID
                            + "/debug/logger" + loggerCount);
                    loggerCount++;
                    if (loggerProp != null) {
                        // parse string and get logger name and log level
                        int slashIndex = loggerProp.indexOf('/');
                        String loggerName = loggerProp.substring(0, slashIndex)
                                .trim();
                        String logLevel = loggerProp.substring(slashIndex + 1,
                                loggerProp.length());
                        // register logger
                        Level level;
                        if (debugEnabled) {
                            level = Level.parse(logLevel);
                        } else {
                            level = Level.OFF;
                        }
                        Logger logger = getLogger(loggerName);
                        initLevel(logger, level);
                        debugMsg("createLoggersFromProperties",
                                "create logger " + loggerName + " with level "
                                        + level.toString());
                    } else {
                        moreLoggers = false;
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}