1 /* 2 * Copyright 2001-2004 The Apache Software Foundation. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package org.apache.commons.logging; 18 19 20 import java.lang.reflect.Constructor; 21 import java.util.Hashtable; 22 23 import org.apache.commons.logging.impl.NoOpLog; 24 25 26 /** 27 * <p>Factory for creating {@link Log} instances. Applications should call 28 * the <code>makeNewLogInstance()</code> method to instantiate new instances 29 * of the configured {@link Log} implementation class.</p> 30 * 31 * <p>By default, calling <code>getInstance()</code> will use the following 32 * algorithm:</p> 33 * <ul> 34 * <li>If Log4J is available, return an instance of 35 * <code>org.apache.commons.logging.impl.Log4JLogger</code>.</li> 36 * <li>If JDK 1.4 or later is available, return an instance of 37 * <code>org.apache.commons.logging.impl.Jdk14Logger</code>.</li> 38 * <li>Otherwise, return an instance of 39 * <code>org.apache.commons.logging.impl.NoOpLog</code>.</li> 40 * </ul> 41 * 42 * <p>You can change the default behavior in one of two ways:</p> 43 * <ul> 44 * <li>On the startup command line, set the system property 45 * <code>org.apache.commons.logging.log</code> to the name of the 46 * <code>org.apache.commons.logging.Log</code> implementation class 47 * you want to use.</li> 48 * <li>At runtime, call <code>LogSource.setLogImplementation()</code>.</li> 49 * </ul> 50 * 51 * @deprecated Use {@link LogFactory} instead - The default factory 52 * implementation performs exactly the same algorithm as this class did 53 * 54 * @author Rod Waldhoff 55 * @version $Id: LogSource.java 155426 2005-02-26 13:10:49Z dirkv $ 56 */ 57 public class LogSource { 58 59 // ------------------------------------------------------- Class Attributes 60 61 static protected Hashtable logs = new Hashtable(); 62 63 /** Is log4j available (in the current classpath) */ 64 static protected boolean log4jIsAvailable = false; 65 66 /** Is JDK 1.4 logging available */ 67 static protected boolean jdk14IsAvailable = false; 68 69 /** Constructor for current log class */ 70 static protected Constructor logImplctor = null; 71 72 73 // ----------------------------------------------------- Class Initializers 74 75 static { 76 77 // Is Log4J Available? 78 try { 79 if (null != Class.forName("org.apache.log4j.Logger")) { 80 log4jIsAvailable = true; 81 } else { 82 log4jIsAvailable = false; 83 } 84 } catch (Throwable t) { 85 log4jIsAvailable = false; 86 } 87 88 // Is JDK 1.4 Logging Available? 89 try { 90 if ((null != Class.forName("java.util.logging.Logger")) && 91 (null != Class.forName("org.apache.commons.logging.impl.Jdk14Logger"))) { 92 jdk14IsAvailable = true; 93 } else { 94 jdk14IsAvailable = false; 95 } 96 } catch (Throwable t) { 97 jdk14IsAvailable = false; 98 } 99 100 // Set the default Log implementation 101 String name = null; 102 try { 103 name = System.getProperty("org.apache.commons.logging.log"); 104 if (name == null) { 105 name = System.getProperty("org.apache.commons.logging.Log"); 106 } 107 } catch (Throwable t) { 108 } 109 if (name != null) { 110 try { 111 setLogImplementation(name); 112 } catch (Throwable t) { 113 try { 114 setLogImplementation 115 ("org.apache.commons.logging.impl.NoOpLog"); 116 } catch (Throwable u) { 117 ; 118 } 119 } 120 } else { 121 try { 122 if (log4jIsAvailable) { 123 setLogImplementation 124 ("org.apache.commons.logging.impl.Log4JLogger"); 125 } else if (jdk14IsAvailable) { 126 setLogImplementation 127 ("org.apache.commons.logging.impl.Jdk14Logger"); 128 } else { 129 setLogImplementation 130 ("org.apache.commons.logging.impl.NoOpLog"); 131 } 132 } catch (Throwable t) { 133 try { 134 setLogImplementation 135 ("org.apache.commons.logging.impl.NoOpLog"); 136 } catch (Throwable u) { 137 ; 138 } 139 } 140 } 141 142 } 143 144 145 // ------------------------------------------------------------ Constructor 146 147 148 /** Don't allow others to create instances */ 149 private LogSource() { 150 } 151 152 153 // ---------------------------------------------------------- Class Methods 154 155 156 /** 157 * Set the log implementation/log implementation factory 158 * by the name of the class. The given class 159 * must implement {@link Log}, and provide a constructor that 160 * takes a single {@link String} argument (containing the name 161 * of the log). 162 */ 163 static public void setLogImplementation(String classname) throws 164 LinkageError, ExceptionInInitializerError, 165 NoSuchMethodException, SecurityException, 166 ClassNotFoundException { 167 try { 168 Class logclass = Class.forName(classname); 169 Class[] argtypes = new Class[1]; 170 argtypes[0] = "".getClass(); 171 logImplctor = logclass.getConstructor(argtypes); 172 } catch (Throwable t) { 173 logImplctor = null; 174 } 175 } 176 177 178 /** 179 * Set the log implementation/log implementation factory 180 * by class. The given class must implement {@link Log}, 181 * and provide a constructor that takes a single {@link String} 182 * argument (containing the name of the log). 183 */ 184 static public void setLogImplementation(Class logclass) throws 185 LinkageError, ExceptionInInitializerError, 186 NoSuchMethodException, SecurityException { 187 Class[] argtypes = new Class[1]; 188 argtypes[0] = "".getClass(); 189 logImplctor = logclass.getConstructor(argtypes); 190 } 191 192 193 /** Get a <code>Log</code> instance by class name */ 194 static public Log getInstance(String name) { 195 Log log = (Log) (logs.get(name)); 196 if (null == log) { 197 log = makeNewLogInstance(name); 198 logs.put(name, log); 199 } 200 return log; 201 } 202 203 204 /** Get a <code>Log</code> instance by class */ 205 static public Log getInstance(Class clazz) { 206 return getInstance(clazz.getName()); 207 } 208 209 210 /** 211 * Create a new {@link Log} implementation, based 212 * on the given <i>name</i>. 213 * <p> 214 * The specific {@link Log} implementation returned 215 * is determined by the value of the 216 * <tt>org.apache.commons.logging.log</tt> property. 217 * The value of <tt>org.apache.commons.logging.log</tt> may be set to 218 * the fully specified name of a class that implements 219 * the {@link Log} interface. This class must also 220 * have a public constructor that takes a single 221 * {@link String} argument (containing the <i>name</i> 222 * of the {@link Log} to be constructed. 223 * <p> 224 * When <tt>org.apache.commons.logging.log</tt> is not set, 225 * or when no corresponding class can be found, 226 * this method will return a Log4JLogger 227 * if the log4j Logger class is 228 * available in the {@link LogSource}'s classpath, or a 229 * Jdk14Logger if we are on a JDK 1.4 or later system, or 230 * NoOpLog if neither of the above conditions is true. 231 * 232 * @param name the log name (or category) 233 */ 234 static public Log makeNewLogInstance(String name) { 235 236 Log log = null; 237 try { 238 Object[] args = new Object[1]; 239 args[0] = name; 240 log = (Log) (logImplctor.newInstance(args)); 241 } catch (Throwable t) { 242 log = null; 243 } 244 if (null == log) { 245 log = new NoOpLog(name); 246 } 247 return log; 248 249 } 250 251 252 /** 253 * Returns a {@link String} array containing the names of 254 * all logs known to me. 255 */ 256 static public String[] getLogNames() { 257 return (String[]) (logs.keySet().toArray(new String[logs.size()])); 258 } 259 260 261 } 262
