001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache license, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the license for the specific language governing permissions and
015 * limitations under the license.
016 */
017package org.apache.logging.log4j.core.pattern;
018
019import java.util.Map;
020import java.util.Set;
021import java.util.TreeSet;
022
023import org.apache.logging.log4j.core.LogEvent;
024import org.apache.logging.log4j.core.config.plugins.Plugin;
025
026/**
027 * Able to handle the contents of the LogEvent's MDC and either
028 * output the entire contents of the properties in a similar format to the
029 * java.util.Hashtable.toString(), or to output the value of a specific key
030 * within the property bundle
031 * when this pattern converter has the option set.
032 */
033@Plugin(name = "MdcPatternConverter", category = PatternConverter.CATEGORY)
034@ConverterKeys({ "X", "mdc", "MDC" })
035public final class MdcPatternConverter extends LogEventPatternConverter {
036    /**
037     * Name of property to output.
038     */
039    private final String key;
040    private final String[] keys;
041    private final boolean full;
042
043    /**
044     * Private constructor.
045     *
046     * @param options options, may be null.
047     */
048    private MdcPatternConverter(final String[] options) {
049        super(options != null && options.length > 0 ? "MDC{" + options[0] + '}' : "MDC", "mdc");
050        if (options != null && options.length > 0) {
051            full = false;
052            if (options[0].indexOf(',') > 0) {
053                keys = options[0].split(",");
054                key = null;
055            } else {
056                keys = null;
057                key = options[0];
058            }
059        } else {
060            full = true;
061            key = null;
062            keys = null;
063        }
064    }
065
066    /**
067     * Obtains an instance of PropertiesPatternConverter.
068     *
069     * @param options options, may be null or first element contains name of property to format.
070     * @return instance of PropertiesPatternConverter.
071     */
072    public static MdcPatternConverter newInstance(final String[] options) {
073        return new MdcPatternConverter(options);
074    }
075
076    /**
077     * {@inheritDoc}
078     */
079    @Override
080    public void format(final LogEvent event, final StringBuilder toAppendTo) {
081        final Map<String, String> contextMap = event.getContextMap();
082        // if there is no additional options, we output every single
083        // Key/Value pair for the MDC in a similar format to Hashtable.toString()
084        if (full) {
085            if (contextMap == null || contextMap.isEmpty()) {
086                toAppendTo.append("{}");
087                return;
088            }
089            final StringBuilder sb = new StringBuilder("{");
090            final Set<String> eventKeys = new TreeSet<>(contextMap.keySet());
091            for (final String eventKey : eventKeys) {
092                if (sb.length() > 1) {
093                    sb.append(", ");
094                }
095                sb.append(eventKey).append('=').append(contextMap.get(eventKey));
096
097            }
098            sb.append('}');
099            toAppendTo.append(sb);
100        } else {
101            if (keys != null) {
102                if (contextMap == null || contextMap.isEmpty()) {
103                    toAppendTo.append("{}");
104                    return;
105                }
106                // Print all the keys in the array that have a value.
107                final StringBuilder sb = new StringBuilder("{");
108                for (String key : keys) {
109                    key = key.trim();
110                    if (contextMap.containsKey(key)) {
111                        if (sb.length() > 1) {
112                            sb.append(", ");
113                        }
114                        sb.append(key).append('=').append(contextMap.get(key));
115                    }
116                }
117                sb.append('}');
118                toAppendTo.append(sb);
119            } else if (contextMap != null){
120                // otherwise they just want a single key output
121                final Object val = contextMap.get(key);
122
123                if (val != null) {
124                    toAppendTo.append(val);
125                }
126            }
127        }
128    }
129}