    001/*
    002 * Copyright 2001-2004 The Apache Software Foundation.
    003 *
    004 * Licensed under the Apache License, Version 2.0 (the "License");
    005 * you may not use this file except in compliance with the License.
    006 * You may obtain a copy of the License at
    007 *
    008 *      http://www.apache.org/licenses/LICENSE-2.0
    009 *
    010 * Unless required by applicable law or agreed to in writing, software
    011 * distributed under the License is distributed on an "AS IS" BASIS,
    012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    013 * See the License for the specific language governing permissions and
    014 * limitations under the License.
    015 */
    016
    017package org.apache.log4j.helpers;
    018
    019/**
    020   This class used to output log statements from within the log4j package.
    021
    022   <p>Log4j components cannot make log4j logging calls. However, it is
    023   sometimes useful for the user to learn about what log4j is
    024   doing. You can enable log4j internal logging by defining the
    025   <b>log4j.configDebug</b> variable.
    026
    027   <p>All log4j internal debug calls go to <code>System.out</code>
    028   where as internal error messages are sent to
    029   <code>System.err</code>. All internal messages are prepended with
    030   the string "log4j: ".
    031
    032   @since 0.8.2
    033   @author Ceki G&uuml;lc&uuml;
    034*/
    035public class LogLog {
    036
    037    /**
    038       Defining this value makes log4j print log4j-internal debug
    039       statements to <code>System.out</code>.
    040
    041      <p> The value of this string is <b>log4j.debug</b>.
    042
    043      <p>Note that the search for all option names is case sensitive.  */
    044    public static final String DEBUG_KEY = "log4j.debug";
    045
    046    /**
    047       Defining this value makes log4j components print log4j-internal
    048       debug statements to <code>System.out</code>.
    049
    050      <p> The value of this string is <b>log4j.configDebug</b>.
    051
    052      <p>Note that the search for all option names is case sensitive.
    053
    054      @deprecated Use {@link #DEBUG_KEY} instead.
    055    */
    056    public static final String CONFIG_DEBUG_KEY = "log4j.configDebug";
    057
    058    protected static boolean debugEnabled = false;
    059
    060    /**
    061       In quietMode not even errors generate any output.
    062     */
    063    private static boolean quietMode = false;
    064
    065    private static final String PREFIX = "log4j: ";
    066    private static final String ERR_PREFIX = "log4j:ERROR ";
    067    private static final String WARN_PREFIX = "log4j:WARN ";
    068
    069    static {
    070    }
    071
    072    /**
    073       Allows to enable/disable log4j internal logging.
    074     */
    075    static public void setInternalDebugging(boolean enabled) {
    076        debugEnabled = enabled;
    077    }
    078
    079    /**
    080       This method is used to output log4j internal debug
    081       statements. Output goes to <code>System.out</code>.
    082    */
    083    public static void debug(String msg) {
    084        if (debugEnabled && !quietMode) {
    085            System.out.println(PREFIX + msg);
    086        }
    087    }
    088
    089    /**
    090       This method is used to output log4j internal debug
    091       statements. Output goes to <code>System.out</code>.
    092    */
    093    public static void debug(String msg, Throwable t) {
    094        if (debugEnabled && !quietMode) {
    095            System.out.println(PREFIX + msg);
    096            if (t != null)
    097                t.printStackTrace(System.out);
    098        }
    099    }
    100
    101    /**
    102       This method is used to output log4j internal error
    103       statements. There is no way to disable error statements.
    104       Output goes to <code>System.err</code>.
    105    */
    106    public static void error(String msg) {
    107        if (quietMode)
    108            return;
    109        System.err.println(ERR_PREFIX + msg);
    110    }
    111
    112    /**
    113       This method is used to output log4j internal error
    114       statements. There is no way to disable error statements.
    115       Output goes to <code>System.err</code>.
    116    */
    117    public static void error(String msg, Throwable t) {
    118        if (quietMode)
    119            return;
    120
    121        System.err.println(ERR_PREFIX + msg);
    122        if (t != null) {
    123            t.printStackTrace();
    124        }
    125    }
    126
    127    /**
    128       In quite mode no LogLog generates strictly no output, not even
    129       for errors.
    130
    131       @param quietMode A true for not
    132    */
    133    public static void setQuietMode(boolean quietMode) {
    134        LogLog.quietMode = quietMode;
    135    }
    136
    137    /**
    138       This method is used to output log4j internal warning
    139       statements. There is no way to disable warning statements.
    140       Output goes to <code>System.err</code>.  */
    141    public static void warn(String msg) {
    142        if (quietMode)
    143            return;
    144
    145        System.err.println(WARN_PREFIX + msg);
    146    }
    147
    148    /**
    149       This method is used to output log4j internal warnings. There is
    150       no way to disable warning statements.  Output goes to
    151       <code>System.err</code>.  */
    152    public static void warn(String msg, Throwable t) {
    153        if (quietMode)
    154            return;
    155
    156        System.err.println(WARN_PREFIX + msg);
    157        if (t != null) {
    158            t.printStackTrace();
    159        }
    160    }
    161}