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.commons.discovery.log; 018 019 import java.lang.reflect.Method; 020 import java.util.Enumeration; 021 import java.util.Hashtable; 022 023 import org.apache.commons.discovery.DiscoveryException; 024 import org.apache.commons.discovery.tools.ClassUtils; 025 import org.apache.commons.logging.Log; 026 import org.apache.commons.logging.LogFactory; 027 028 029 /** 030 * <p>Simple implementation of Log that sends all enabled log messages, 031 * for all defined loggers, to System.err. 032 * </p> 033 * 034 * <p>Hacked from commons-logging SimpleLog for use in discovery. 035 * This is intended to be enough of a Log implementation to bootstrap 036 * Discovery. 037 * </p> 038 * 039 * <p>One property: <code>org.apache.commons.discovery.log.level</code>. 040 * valid values: all, trace, debug, info, warn, error, fatal, off. 041 * </p> 042 * 043 * @author Richard A. Sitze 044 * @author <a href="mailto:sanders@apache.org">Scott Sanders</a> 045 * @author Rod Waldhoff 046 * @author Robert Burrell Donkin 047 * 048 * @version $Id: DiscoveryLogFactory.java 480374 2006-11-29 03:33:25Z niallp $ 049 */ 050 public class DiscoveryLogFactory { 051 private static LogFactory logFactory = null; 052 private static final Hashtable classRegistry = new Hashtable(); 053 private static final Class[] setLogParamClasses = new Class[] { Log.class }; 054 055 /** 056 * Above fields must be initialied before this one.. 057 */ 058 private static Log log = DiscoveryLogFactory._newLog(DiscoveryLogFactory.class); 059 060 /** 061 */ 062 public static Log newLog(Class clazz) { 063 /** 064 * Required to implement 'public static void setLog(Log)' 065 */ 066 try { 067 Method setLog = ClassUtils.findPublicStaticMethod(clazz, 068 void.class, 069 "setLog", 070 setLogParamClasses); 071 072 if (setLog == null) { 073 String msg = "Internal Error: " + clazz.getName() + " required to implement 'public static void setLog(Log)'"; 074 log.fatal(msg); 075 throw new DiscoveryException(msg); 076 } 077 } catch (SecurityException se) { 078 String msg = "Required Security Permissions not present"; 079 log.fatal(msg, se); 080 throw new DiscoveryException(msg, se); 081 } 082 083 if (log.isDebugEnabled()) 084 log.debug("Class meets requirements: " + clazz.getName()); 085 086 return _newLog(clazz); 087 } 088 089 /** 090 * This method MUST not invoke any logging.. 091 */ 092 public static Log _newLog(Class clazz) { 093 classRegistry.put(clazz, clazz); 094 095 return (logFactory == null) 096 ? new SimpleLog(clazz.getName()) 097 : logFactory.getInstance(clazz.getName()); 098 } 099 100 public static void setLog(Log _log) { 101 log = _log; 102 } 103 104 /** 105 * Set logFactory, works ONLY on first call. 106 */ 107 public static void setFactory(LogFactory factory) { 108 if (logFactory == null) { 109 // for future generations.. if any 110 logFactory = factory; 111 112 // now, go back and reset loggers for all current classes.. 113 Enumeration elements = classRegistry.elements(); 114 while (elements.hasMoreElements()) { 115 Class clazz = (Class)elements.nextElement(); 116 117 if (log.isDebugEnabled()) 118 log.debug("Reset Log for: " + clazz.getName()); 119 120 Method setLog = null; 121 122 // invoke 'setLog(Log)'.. we already know it's 'public static', 123 // have verified parameters, and return type.. 124 try { 125 setLog = clazz.getMethod("setLog", setLogParamClasses); 126 } catch(Exception e) { 127 String msg = "Internal Error: pre-check for " + clazz.getName() + " failed?!"; 128 log.fatal(msg, e); 129 throw new DiscoveryException(msg, e); 130 } 131 132 Object[] setLogParam = new Object[] { factory.getInstance(clazz.getName()) }; 133 134 try { 135 setLog.invoke(null, setLogParam); 136 } catch(Exception e) { 137 String msg = "Internal Error: setLog failed for " + clazz.getName(); 138 log.fatal(msg, e); 139 throw new DiscoveryException(msg, e); 140 } 141 } 142 } 143 } 144 }