    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     */
    017    package org.apache.logging.log4j.core.lookup;
    018
    019    import java.util.HashMap;
    020    import java.util.List;
    021    import java.util.Map;
    022
    023    import org.apache.logging.log4j.Logger;
    024    import org.apache.logging.log4j.core.LogEvent;
    025    import org.apache.logging.log4j.core.config.plugins.util.PluginManager;
    026    import org.apache.logging.log4j.core.config.plugins.util.PluginType;
    027    import org.apache.logging.log4j.core.util.Loader;
    028    import org.apache.logging.log4j.core.util.ReflectionUtil;
    029    import org.apache.logging.log4j.status.StatusLogger;
    030
    031    /**
    032     * Proxies all the other {@link StrLookup}s.
    033     */
    034    public class Interpolator extends AbstractLookup {
    035
    036        private static final Logger LOGGER = StatusLogger.getLogger();
    037
    038        /** Constant for the prefix separator. */
    039        private static final char PREFIX_SEPARATOR = ':';
    040
    041        private final Map<String, StrLookup> lookups = new HashMap<String, StrLookup>();
    042
    043        private final StrLookup defaultLookup;
    044
    045        public Interpolator(final StrLookup defaultLookup) {
    046            this(defaultLookup, null);
    047        }
    048
    049        /**
    050         * Constructs an Interpolator using a given StrLookup and a list of packages to find Lookup plugins in.
    051         *
    052         * @param defaultLookup  the default StrLookup to use as a fallback
    053         * @param pluginPackages a list of packages to scan for Lookup plugins
    054         * @since 2.1
    055         */
    056        public Interpolator(final StrLookup defaultLookup, final List<String> pluginPackages) {
    057            this.defaultLookup = defaultLookup == null ? new MapLookup(new HashMap<String, String>()) : defaultLookup;
    058            final PluginManager manager = new PluginManager(CATEGORY);
    059            manager.collectPlugins(pluginPackages);
    060            final Map<String, PluginType<?>> plugins = manager.getPlugins();
    061
    062            for (final Map.Entry<String, PluginType<?>> entry : plugins.entrySet()) {
    063                try {
    064                    final Class<? extends StrLookup> clazz = entry.getValue().getPluginClass().asSubclass(StrLookup.class);
    065                    lookups.put(entry.getKey(), ReflectionUtil.instantiate(clazz));
    066                } catch (final Exception ex) {
    067                    LOGGER.error("Unable to create Lookup for {}", entry.getKey(), ex);
    068                }
    069            }
    070        }
    071
    072        /**
    073         * Create the default Interpolator using only Lookups that work without an event.
    074         */
    075        public Interpolator() {
    076            this((Map<String, String>) null);
    077        }
    078
    079        /**
    080         * Creates the Interpolator using only Lookups that work without an event and initial properties.
    081         */
    082        public Interpolator(final Map<String, String> properties) {
    083            this.defaultLookup = new MapLookup(properties == null ? new HashMap<String, String>() : properties);
    084            // TODO: this ought to use the PluginManager
    085            lookups.put("sys", new SystemPropertiesLookup());
    086            lookups.put("env", new EnvironmentLookup());
    087            lookups.put("main", MapLookup.MAIN_SINGLETON);
    088            lookups.put("java", new JavaLookup());
    089            // JNDI
    090            try {
    091                // [LOG4J2-703] We might be on Android
    092                lookups.put("jndi",
    093                    Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JndiLookup", StrLookup.class));
    094            } catch (final Throwable e) {
    095                // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JndiLookup
    096                LOGGER.warn(
    097                        "JNDI lookup class is not available because this JRE does not support JNDI. JNDI string lookups will not be available, continuing configuration.",
    098                        e);
    099            }
    100            // JMX input args
    101            try {
    102                // We might be on Android
    103                lookups.put("jvmrunargs",
    104                    Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JmxRuntimeInputArgumentsLookup", StrLookup.class));
    105            } catch (final Throwable e) {
    106                // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JmxRuntimeInputArgumentsLookup
    107                LOGGER.warn(
    108                        "JMX runtime input lookup class is not available because this JRE does not support JMX. JMX lookups will not be available, continuing configuration.",
    109                        e);
    110            }
    111            lookups.put("date", new DateLookup());
    112            lookups.put("ctx", new ContextMapLookup());
    113            if (Loader.isClassAvailable("javax.servlet.ServletContext")) {
    114                try {
    115                    lookups.put("web",
    116                        Loader.newCheckedInstanceOf("org.apache.logging.log4j.web.WebLookup", StrLookup.class));
    117                } catch (final Exception ignored) {
    118                    LOGGER.info("Log4j appears to be running in a Servlet environment, but there's no log4j-web module " +
    119                        "available. If you want better web container support, please add the log4j-web JAR to your " +
    120                        "web archive or server lib directory.");
    121                }
    122            } else {
    123                LOGGER.debug("Not in a ServletContext environment, thus not loading WebLookup plugin.");
    124            }
    125        }
    126
    127        /**
    128         * Resolves the specified variable. This implementation will try to extract
    129         * a variable prefix from the given variable name (the first colon (':') is
    130         * used as prefix separator). It then passes the name of the variable with
    131         * the prefix stripped to the lookup object registered for this prefix. If
    132         * no prefix can be found or if the associated lookup object cannot resolve
    133         * this variable, the default lookup object will be used.
    134         *
    135         * @param event The current LogEvent or null.
    136         * @param var the name of the variable whose value is to be looked up
    137         * @return the value of this variable or <b>null</b> if it cannot be
    138         * resolved
    139         */
    140        @Override
    141        public String lookup(final LogEvent event, String var) {
    142            if (var == null) {
    143                return null;
    144            }
    145
    146            final int prefixPos = var.indexOf(PREFIX_SEPARATOR);
    147            if (prefixPos >= 0) {
    148                final String prefix = var.substring(0, prefixPos);
    149                final String name = var.substring(prefixPos + 1);
    150                final StrLookup lookup = lookups.get(prefix);
    151                String value = null;
    152                if (lookup != null) {
    153                    value = event == null ? lookup.lookup(name) : lookup.lookup(event, name);
    154                }
    155
    156                if (value != null) {
    157                    return value;
    158                }
    159                var = var.substring(prefixPos + 1);
    160            }
    161            if (defaultLookup != null) {
    162                return event == null ? defaultLookup.lookup(var) : defaultLookup.lookup(event, var);
    163            }
    164            return null;
    165        }
    166
    167        @Override
    168        public String toString() {
    169            final StringBuilder sb = new StringBuilder();
    170            for (final String name : lookups.keySet()) {
    171                if (sb.length() == 0) {
    172                    sb.append('{');
    173                } else {
    174                    sb.append(", ");
    175                }
    176
    177                sb.append(name);
    178            }
    179            if (sb.length() > 0) {
    180                sb.append('}');
    181            }
    182            return sb.toString();
    183        }
    184    }