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 * Proxies 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 // [LOG4J2-703] We might be on Android 077 lookups.put("jndi", 078 Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JndiLookup", StrLookup.class)); 079 } catch (Throwable e) { 080 // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JndiLookup 081 LOGGER.warn( 082 "JNDI lookup class is not available because this JRE does not support JNDI. JNDI string lookups will not be available, continuing configuration.", 083 e); 084 } 085 lookups.put("date", new DateLookup()); 086 lookups.put("ctx", new ContextMapLookup()); 087 if (Loader.isClassAvailable("javax.servlet.ServletContext")) { 088 try { 089 lookups.put("web", 090 Loader.newCheckedInstanceOf("org.apache.logging.log4j.web.WebLookup", StrLookup.class)); 091 } catch (final Exception ignored) { 092 LOGGER.info("Log4j appears to be running in a Servlet environment, but there's no log4j-web module " + 093 "available. If you want better web container support, please add the log4j-web JAR to your " + 094 "web archive or server lib directory."); 095 } 096 } else { 097 LOGGER.debug("Not in a ServletContext environment, thus not loading WebLookup plugin."); 098 } 099 } 100 101 /** 102 * Resolves the specified variable. This implementation will try to extract 103 * a variable prefix from the given variable name (the first colon (':') is 104 * used as prefix separator). It then passes the name of the variable with 105 * the prefix stripped to the lookup object registered for this prefix. If 106 * no prefix can be found or if the associated lookup object cannot resolve 107 * this variable, the default lookup object will be used. 108 * 109 * @param var the name of the variable whose value is to be looked up 110 * @return the value of this variable or <b>null</b> if it cannot be 111 * resolved 112 */ 113 @Override 114 public String lookup(final String var) { 115 return lookup(null, var); 116 } 117 118 /** 119 * Resolves the specified variable. This implementation will try to extract 120 * a variable prefix from the given variable name (the first colon (':') is 121 * used as prefix separator). It then passes the name of the variable with 122 * the prefix stripped to the lookup object registered for this prefix. If 123 * no prefix can be found or if the associated lookup object cannot resolve 124 * this variable, the default lookup object will be used. 125 * 126 * @param event The current LogEvent or null. 127 * @param var the name of the variable whose value is to be looked up 128 * @return the value of this variable or <b>null</b> if it cannot be 129 * resolved 130 */ 131 @Override 132 public String lookup(final LogEvent event, String var) { 133 if (var == null) { 134 return null; 135 } 136 137 final int prefixPos = var.indexOf(PREFIX_SEPARATOR); 138 if (prefixPos >= 0) { 139 final String prefix = var.substring(0, prefixPos); 140 final String name = var.substring(prefixPos + 1); 141 final StrLookup lookup = lookups.get(prefix); 142 String value = null; 143 if (lookup != null) { 144 value = event == null ? lookup.lookup(name) : lookup.lookup(event, name); 145 } 146 147 if (value != null) { 148 return value; 149 } 150 var = var.substring(prefixPos + 1); 151 } 152 if (defaultLookup != null) { 153 return event == null ? defaultLookup.lookup(var) : defaultLookup.lookup(event, var); 154 } 155 return null; 156 } 157 158 @Override 159 public String toString() { 160 final StringBuilder sb = new StringBuilder(); 161 for (final String name : lookups.keySet()) { 162 if (sb.length() == 0) { 163 sb.append('{'); 164 } else { 165 sb.append(", "); 166 } 167 168 sb.append(name); 169 } 170 if (sb.length() > 0) { 171 sb.append('}'); 172 } 173 return sb.toString(); 174 } 175 }