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