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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements. See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache license, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License. You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the license for the specific language governing permissions and
    15   * limitations under the license.
    16   */
    17  package org.apache.logging.log4j.core.lookup;
    18
    19  import java.util.HashMap;
    20  import java.util.List;
    21  import java.util.Map;
    22
    23  import org.apache.logging.log4j.Logger;
    24  import org.apache.logging.log4j.core.LogEvent;
    25  import org.apache.logging.log4j.core.config.plugins.util.PluginManager;
    26  import org.apache.logging.log4j.core.config.plugins.util.PluginType;
    27  import org.apache.logging.log4j.core.util.Loader;
    28  import org.apache.logging.log4j.core.util.ReflectionUtil;
    29  import org.apache.logging.log4j.status.StatusLogger;
    30
    31  /**
    32   * Proxies all the other {@link StrLookup}s.
    33   */
    34  public class Interpolator extends AbstractLookup {
    35
    36      private static final Logger LOGGER = StatusLogger.getLogger();
    37
    38      /** Constant for the prefix separator. */
    39      private static final char PREFIX_SEPARATOR = ':';
    40
    41      private final Map<String, StrLookup> lookups = new HashMap<String, StrLookup>();
    42
    43      private final StrLookup defaultLookup;
    44
    45      public Interpolator(final StrLookup defaultLookup) {
    46          this(defaultLookup, null);
    47      }
    48
    49      /**
    50       * Constructs an Interpolator using a given StrLookup and a list of packages to find Lookup plugins in.
    51       *
    52       * @param defaultLookup  the default StrLookup to use as a fallback
    53       * @param pluginPackages a list of packages to scan for Lookup plugins
    54       * @since 2.1
    55       */
    56      public Interpolator(final StrLookup defaultLookup, final List<String> pluginPackages) {
    57          this.defaultLookup = defaultLookup == null ? new MapLookup(new HashMap<String, String>()) : defaultLookup;
    58          final PluginManager manager = new PluginManager(CATEGORY);
    59          manager.collectPlugins(pluginPackages);
    60          final Map<String, PluginType<?>> plugins = manager.getPlugins();
    61
    62          for (final Map.Entry<String, PluginType<?>> entry : plugins.entrySet()) {
    63              try {
    64                  final Class<? extends StrLookup> clazz = entry.getValue().getPluginClass().asSubclass(StrLookup.class);
    65                  lookups.put(entry.getKey(), ReflectionUtil.instantiate(clazz));
    66              } catch (final Exception ex) {
    67                  LOGGER.error("Unable to create Lookup for {}", entry.getKey(), ex);
    68              }
    69          }
    70      }
    71
    72      /**
    73       * Create the default Interpolator using only Lookups that work without an event.
    74       */
    75      public Interpolator() {
    76          this((Map<String, String>) null);
    77      }
    78
    79      /**
    80       * Creates the Interpolator using only Lookups that work without an event and initial properties.
    81       */
    82      public Interpolator(final Map<String, String> properties) {
    83          this.defaultLookup = new MapLookup(properties == null ? new HashMap<String, String>() : properties);
    84          // TODO: this ought to use the PluginManager
    85          lookups.put("sys", new SystemPropertiesLookup());
    86          lookups.put("env", new EnvironmentLookup());
    87          lookups.put("main", MapLookup.MAIN_SINGLETON);
    88          lookups.put("java", new JavaLookup());
    89          // JNDI
    90          try {
    91              // [LOG4J2-703] We might be on Android
    92              lookups.put("jndi",
    93                  Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JndiLookup", StrLookup.class));
    94          } catch (final Throwable e) {
    95              // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JndiLookup
    96              LOGGER.warn(
    97                      "JNDI lookup class is not available because this JRE does not support JNDI. JNDI string lookups will not be available, continuing configuration.",
    98                      e);
    99          }
    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 }