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 lookups.put("jndi", new JndiLookup()); 076 lookups.put("date", new DateLookup()); 077 lookups.put("ctx", new ContextMapLookup()); 078 if (Loader.isClassAvailable("javax.servlet.ServletContext")) { 079 try { 080 lookups.put("web", 081 Loader.newCheckedInstanceOf("org.apache.logging.log4j.web.WebLookup", StrLookup.class)); 082 } catch (final Exception ignored) { 083 LOGGER.info("Log4j appears to be running in a Servlet environment, but there's no log4j-web module " + 084 "available. If you want better web container support, please add the log4j-web JAR to your " + 085 "web archive or server lib directory."); 086 } 087 } else { 088 LOGGER.debug("Not in a ServletContext environment, thus not loading WebLookup plugin."); 089 } 090 } 091 092 /** 093 * Resolves the specified variable. This implementation will try to extract 094 * a variable prefix from the given variable name (the first colon (':') is 095 * used as prefix separator). It then passes the name of the variable with 096 * the prefix stripped to the lookup object registered for this prefix. If 097 * no prefix can be found or if the associated lookup object cannot resolve 098 * this variable, the default lookup object will be used. 099 * 100 * @param var the name of the variable whose value is to be looked up 101 * @return the value of this variable or <b>null</b> if it cannot be 102 * resolved 103 */ 104 @Override 105 public String lookup(final String var) { 106 return lookup(null, var); 107 } 108 109 /** 110 * Resolves the specified variable. This implementation will try to extract 111 * a variable prefix from the given variable name (the first colon (':') is 112 * used as prefix separator). It then passes the name of the variable with 113 * the prefix stripped to the lookup object registered for this prefix. If 114 * no prefix can be found or if the associated lookup object cannot resolve 115 * this variable, the default lookup object will be used. 116 * 117 * @param event The current LogEvent or null. 118 * @param var the name of the variable whose value is to be looked up 119 * @return the value of this variable or <b>null</b> if it cannot be 120 * resolved 121 */ 122 @Override 123 public String lookup(final LogEvent event, String var) { 124 if (var == null) { 125 return null; 126 } 127 128 final int prefixPos = var.indexOf(PREFIX_SEPARATOR); 129 if (prefixPos >= 0) { 130 final String prefix = var.substring(0, prefixPos); 131 final String name = var.substring(prefixPos + 1); 132 final StrLookup lookup = lookups.get(prefix); 133 String value = null; 134 if (lookup != null) { 135 value = event == null ? lookup.lookup(name) : lookup.lookup(event, name); 136 } 137 138 if (value != null) { 139 return value; 140 } 141 var = var.substring(prefixPos + 1); 142 } 143 if (defaultLookup != null) { 144 return event == null ? defaultLookup.lookup(var) : defaultLookup.lookup(event, var); 145 } 146 return null; 147 } 148 149 @Override 150 public String toString() { 151 final StringBuilder sb = new StringBuilder(); 152 for (final String name : lookups.keySet()) { 153 if (sb.length() == 0) { 154 sb.append('{'); 155 } else { 156 sb.append(", "); 157 } 158 159 sb.append(name); 160 } 161 if (sb.length() > 0) { 162 sb.append('}'); 163 } 164 return sb.toString(); 165 } 166 }