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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.impl;
18  
19  import org.apache.logging.log4j.core.LoggerContext;
20  import org.apache.logging.log4j.core.helpers.Constants;
21  import org.apache.logging.log4j.core.helpers.Loader;
22  import org.apache.logging.log4j.core.selector.ClassLoaderContextSelector;
23  import org.apache.logging.log4j.core.selector.ContextSelector;
24  import org.apache.logging.log4j.status.StatusLogger;
25  import org.apache.logging.log4j.spi.LoggerContextFactory;
26  import org.apache.logging.log4j.util.PropertiesUtil;
27  
28  /**
29   * Factory to locate a ContextSelector and then load a LoggerContext.
30   */
31  public class Log4jContextFactory implements LoggerContextFactory {
32  
33      private static final StatusLogger LOGGER = StatusLogger.getLogger();
34  
35      private ContextSelector selector;
36  
37      /**
38       * Constructor that initializes the ContextSelector.
39       */
40      public Log4jContextFactory() {
41          final String sel = PropertiesUtil.getProperties().getStringProperty(Constants.LOG4J_CONTEXT_SELECTOR);
42          if (sel != null) {
43              try {
44                  final Class clazz = Loader.loadClass(sel);
45                  if (clazz != null && ContextSelector.class.isAssignableFrom(clazz)) {
46                      selector = (ContextSelector) clazz.newInstance();
47                      return;
48                  }
49              } catch (final Exception ex) {
50                  LOGGER.error("Unable to create context " + sel, ex);
51              }
52  
53          }
54          selector = new ClassLoaderContextSelector();
55      }
56  
57      /**
58       * Returns the ContextSelector.
59       * @return The ContextSelector.
60       */
61      public ContextSelector getSelector() {
62          return selector;
63      }
64  
65      /**
66       * Load the LoggerContext using the ContextSelector.
67       * @param fqcn The fully qualified class name of the caller.
68       * @param loader The ClassLoader to use or null.
69       * @param currentContext If true returns the current Context, if false returns the Context appropriate
70       * for the caller if a more appropriate Context can be determined.
71       * @return The LoggerContext.
72       */
73      public LoggerContext getContext(final String fqcn, final ClassLoader loader, final boolean currentContext) {
74          final LoggerContext ctx = selector.getContext(fqcn, loader, currentContext);
75          if (ctx.getStatus() == LoggerContext.Status.INITIALIZED) {
76              ctx.start();
77          }
78          return ctx;
79      }
80  }