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 * @deprecated Please use {@link java.net.URL#openConnection} instead. 58 * Please visit <a href="http://android-developers.blogspot.com/2011/09/androids-http-clients.html">this webpage</a> 59 * for further details. 60 */ 61 @Deprecated 62 public class LogSource { 63 64 // ------------------------------------------------------- Class Attributes 65 66 static protected Hashtable logs = new Hashtable(); 67 68 /** Is log4j available (in the current classpath) */ 69 static protected boolean log4jIsAvailable = false; 70 71 /** Is JDK 1.4 logging available */ 72 static protected boolean jdk14IsAvailable = false; 73 74 /** Constructor for current log class */ 75 static protected Constructor logImplctor = null; 76 77 78 // ----------------------------------------------------- Class Initializers 79 80 static { 81 82 // Is Log4J Available? 83 try { 84 if (null != Class.forName("org.apache.log4j.Logger")) { 85 log4jIsAvailable = true; 86 } else { 87 log4jIsAvailable = false; 88 } 89 } catch (Throwable t) { 90 log4jIsAvailable = false; 91 } 92 93 // Is JDK 1.4 Logging Available? 94 try { 95 if ((null != Class.forName("java.util.logging.Logger")) && 96 (null != Class.forName("org.apache.commons.logging.impl.Jdk14Logger"))) { 97 jdk14IsAvailable = true; 98 } else { 99 jdk14IsAvailable = false; 100 } 101 } catch (Throwable t) { 102 jdk14IsAvailable = false; 103 } 104 105 // Set the default Log implementation 106 String name = null; 107 try { 108 name = System.getProperty("org.apache.commons.logging.log"); 109 if (name == null) { 110 name = System.getProperty("org.apache.commons.logging.Log"); 111 } 112 } catch (Throwable t) { 113 } 114 if (name != null) { 115 try { 116 setLogImplementation(name); 117 } catch (Throwable t) { 118 try { 119 setLogImplementation 120 ("org.apache.commons.logging.impl.NoOpLog"); 121 } catch (Throwable u) { 122 ; 123 } 124 } 125 } else { 126 try { 127 if (log4jIsAvailable) { 128 setLogImplementation 129 ("org.apache.commons.logging.impl.Log4JLogger"); 130 } else if (jdk14IsAvailable) { 131 setLogImplementation 132 ("org.apache.commons.logging.impl.Jdk14Logger"); 133 } else { 134 setLogImplementation 135 ("org.apache.commons.logging.impl.NoOpLog"); 136 } 137 } catch (Throwable t) { 138 try { 139 setLogImplementation 140 ("org.apache.commons.logging.impl.NoOpLog"); 141 } catch (Throwable u) { 142 ; 143 } 144 } 145 } 146 147 } 148 149 150 // ------------------------------------------------------------ Constructor 151 152 153 /** Don't allow others to create instances */ 154 private LogSource() { 155 } 156 157 158 // ---------------------------------------------------------- Class Methods 159 160 161 /** 162 * Set the log implementation/log implementation factory 163 * by the name of the class. The given class 164 * must implement {@link Log}, and provide a constructor that 165 * takes a single {@link String} argument (containing the name 166 * of the log). 167 */ 168 static public void setLogImplementation(String classname) throws 169 LinkageError, ExceptionInInitializerError, 170 NoSuchMethodException, SecurityException, 171 ClassNotFoundException { 172 try { 173 Class logclass = Class.forName(classname); 174 Class[] argtypes = new Class[1]; 175 argtypes[0] = "".getClass(); 176 logImplctor = logclass.getConstructor(argtypes); 177 } catch (Throwable t) { 178 logImplctor = null; 179 } 180 } 181 182 183 /** 184 * Set the log implementation/log implementation factory 185 * by class. The given class must implement {@link Log}, 186 * and provide a constructor that takes a single {@link String} 187 * argument (containing the name of the log). 188 */ 189 static public void setLogImplementation(Class logclass) throws 190 LinkageError, ExceptionInInitializerError, 191 NoSuchMethodException, SecurityException { 192 Class[] argtypes = new Class[1]; 193 argtypes[0] = "".getClass(); 194 logImplctor = logclass.getConstructor(argtypes); 195 } 196 197 198 /** Get a <code>Log</code> instance by class name */ 199 static public Log getInstance(String name) { 200 Log log = (Log) (logs.get(name)); 201 if (null == log) { 202 log = makeNewLogInstance(name); 203 logs.put(name, log); 204 } 205 return log; 206 } 207 208 209 /** Get a <code>Log</code> instance by class */ 210 static public Log getInstance(Class clazz) { 211 return getInstance(clazz.getName()); 212 } 213 214 215 /** 216 * Create a new {@link Log} implementation, based 217 * on the given <i>name</i>. 218 * <p> 219 * The specific {@link Log} implementation returned 220 * is determined by the value of the 221 * <tt>org.apache.commons.logging.log</tt> property. 222 * The value of <tt>org.apache.commons.logging.log</tt> may be set to 223 * the fully specified name of a class that implements 224 * the {@link Log} interface. This class must also 225 * have a public constructor that takes a single 226 * {@link String} argument (containing the <i>name</i> 227 * of the {@link Log} to be constructed. 228 * <p> 229 * When <tt>org.apache.commons.logging.log</tt> is not set, 230 * or when no corresponding class can be found, 231 * this method will return a Log4JLogger 232 * if the log4j Logger class is 233 * available in the {@link LogSource}'s classpath, or a 234 * Jdk14Logger if we are on a JDK 1.4 or later system, or 235 * NoOpLog if neither of the above conditions is true. 236 * 237 * @param name the log name (or category) 238 */ 239 static public Log makeNewLogInstance(String name) { 240 241 Log log = null; 242 try { 243 Object[] args = new Object[1]; 244 args[0] = name; 245 log = (Log) (logImplctor.newInstance(args)); 246 } catch (Throwable t) { 247 log = null; 248 } 249 if (null == log) { 250 log = new NoOpLog(name); 251 } 252 return log; 253 254 } 255 256 257 /** 258 * Returns a {@link String} array containing the names of 259 * all logs known to me. 260 */ 261 static public String[] getLogNames() { 262 return (String[]) (logs.keySet().toArray(new String[logs.size()])); 263 } 264 265 266 } 267
