log4j-over-slf4j/src/main/java/org/apache/log4j/Level.java

/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * 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.
 */

// Contributors:  Kitching Simon <Simon.Kitching@orange.ch>
//                Nicholas Wolff

package org.apache.log4j;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamException;
import java.io.Serializable;

/**
 * Defines the minimum set of levels recognized by the system, that is
 * <code>OFF</code>, <code>FATAL</code>, <code>ERROR</code>, <code>WARN</code>,
 * <code>INFO</code>, <code>DEBUG</code> and <code>ALL</code>.
 * 
 * <p>
 * The <code>Level</code> class may be subclassed to define a larger level set.
 * 
 * @author Ceki G&uuml;lc&uuml;
 * 
 */
public class Level extends Priority implements Serializable {

    /**
     * TRACE level integer value.
     * 
     * @since 1.2.12
     */
    public static final int TRACE_INT = 5000;

    // match jboss' xlevel
    public static final int X_TRACE_INT = DEBUG_INT - 100;

    /**
     * The <code>OFF</code> has the highest possible rank and is intended to turn
     * off logging.
     */
    final static public Level OFF = new Level(OFF_INT, "OFF", 0);

    /**
     * The <code>FATAL</code> level designates very severe error events that will
     * presumably lead the application to abort.
     */
    final static public Level FATAL = new Level(FATAL_INT, "FATAL", 0);

    /**
     * The <code>ERROR</code> level designates error events that might still allow
     * the application to continue running.
     */
    final static public Level ERROR = new Level(ERROR_INT, "ERROR", 3);

    /**
     * The <code>WARN</code> level designates potentially harmful situations.
     */
    final static public Level WARN = new Level(WARN_INT, "WARN", 4);

    /**
     * The <code>INFO</code> level designates informational messages that highlight
     * the progress of the application at coarse-grained level.
     */
    final static public Level INFO = new Level(INFO_INT, "INFO", 6);

    /**
     * The <code>DEBUG</code> Level designates fine-grained informational events
     * that are most useful to debug an application.
     */
    final static public Level DEBUG = new Level(DEBUG_INT, "DEBUG", 7);

    /**
     * The <code>TRACE</code> Level designates finer-grained informational events
     * than the <code>DEBUG</code> level.
     * 
     * @since 1.2.12
     */
    public static final Level TRACE = new Level(TRACE_INT, "TRACE", 7);

    /**
     * The <code>ALL</code> has the lowest possible rank and is intended to turn on
     * all logging.
     */
    final static public Level ALL = new Level(ALL_INT, "ALL", 7);

    /**
     * Serialization version id.
     */
    static final long serialVersionUID = 3491141966387921974L;

    /**
     * Instantiate a Level object.
     * 
     * @param level a level
     * @param levelStr  a level string
     * @param syslogEquivalent  the Syslog equivalent
     */
    protected Level(int level, String levelStr, int syslogEquivalent) {
        super(level, levelStr, syslogEquivalent);
    }

    /**
     * Convert the string passed as argument to a level. If the conversion fails,
     * then this method returns {@link #DEBUG}.
     * 
     * @param sArg a string
     * @return corresponding Level
     * 
     */
    public static Level toLevel(String sArg) {
        return (Level) toLevel(sArg, Level.DEBUG);
    }

    /**
     * Convert an integer passed as argument to a level. If the conversion fails,
     * then this method returns {@link #DEBUG}.
     * 
     * @param val an int
     * @return a level
     */
    public static Level toLevel(int val) {
        return (Level) toLevel(val, Level.DEBUG);
    }

    /**
     * Convert an integer passed as argument to a level. If the conversion fails,
     * then this method returns the specified default.
     * 
     * @param val a value 
     * @param defaultLevel a defaultLevel
     * @return corresponding Level
     */
    public static Level toLevel(int val, Level defaultLevel) {
        switch (val) {
        case ALL_INT:
            return ALL;
        case DEBUG_INT:
            return Level.DEBUG;
        case INFO_INT:
            return Level.INFO;
        case WARN_INT:
            return Level.WARN;
        case ERROR_INT:
            return Level.ERROR;
        case FATAL_INT:
            return Level.FATAL;
        case OFF_INT:
            return OFF;
        case TRACE_INT:
            return Level.TRACE;
        default:
            return defaultLevel;
        }
    }

    /**
     * Convert the string passed as argument to a level. If the conversion fails,
     * then this method returns the value of <code>defaultLevel</code>.
     *
     * @param sArg a string 
     * @param defaultLevel a default level
     * @return corresponding level
     */
    public static Level toLevel(String sArg, Level defaultLevel) {
        if (sArg == null)
            return defaultLevel;

        String s = sArg.toUpperCase();

        if (s.equals("ALL"))
            return Level.ALL;
        if (s.equals("DEBUG"))
            return Level.DEBUG;
        if (s.equals("INFO"))
            return Level.INFO;
        if (s.equals("WARN"))
            return Level.WARN;
        if (s.equals("ERROR"))
            return Level.ERROR;
        if (s.equals("FATAL"))
            return Level.FATAL;
        if (s.equals("OFF"))
            return Level.OFF;
        if (s.equals("TRACE"))
            return Level.TRACE;
        return defaultLevel;
    }

    /**
     * Custom deserialization of Level.
     * 
     * @param s serialization stream.
     * @throws IOException            if IO exception.
     * @throws ClassNotFoundException if class not found.
     */
    private void readObject(final ObjectInputStream s) throws IOException, ClassNotFoundException {
        s.defaultReadObject();
        level = s.readInt();
        syslogEquivalent = s.readInt();
        levelStr = s.readUTF();
        if (levelStr == null) {
            levelStr = "";
        }
    }

    /**
     * Serialize level.
     * 
     * @param s serialization stream.
     * @throws IOException if exception during serialization.
     */
    private void writeObject(final ObjectOutputStream s) throws IOException {
        s.defaultWriteObject();
        s.writeInt(level);
        s.writeInt(syslogEquivalent);
        s.writeUTF(levelStr);
    }

    /**
     * Resolved deserialized level to one of the stock instances. May be overridden
     * in classes derived from Level.
     * 
     * @return resolved object.
     * @throws ObjectStreamException if exception during resolution.
     */
    private Object readResolve() throws ObjectStreamException {
        //
        // if the deserialized object is exactly an instance of Level
        //
        if (getClass() == Level.class) {
            return toLevel(level);
        }
        //
        // extension of Level can't substitute stock item
        //
        return this;
    }
}