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 18 package org.apache.commons.logging; 19 20 /** 21 * <p>A simple logging interface abstracting logging APIs. In order to be 22 * instantiated successfully by {@link LogFactory}, classes that implement 23 * this interface must have a constructor that takes a single String 24 * parameter representing the "name" of this Log.</p> 25 * 26 * <p> The six logging levels used by <code>Log</code> are (in order): 27 * <ol> 28 * <li>trace (the least serious)</li> 29 * <li>debug</li> 30 * <li>info</li> 31 * <li>warn</li> 32 * <li>error</li> 33 * <li>fatal (the most serious)</li> 34 * </ol> 35 * The mapping of these log levels to the concepts used by the underlying 36 * logging system is implementation dependent. 37 * The implemention should ensure, though, that this ordering behaves 38 * as expected.</p> 39 * 40 * <p>Performance is often a logging concern. 41 * By examining the appropriate property, 42 * a component can avoid expensive operations (producing information 43 * to be logged).</p> 44 * 45 * <p> For example, 46 * <code><pre> 47 * if (log.isDebugEnabled()) { 48 * ... do something expensive ... 49 * log.debug(theResult); 50 * } 51 * </pre></code> 52 * </p> 53 * 54 * <p>Configuration of the underlying logging system will generally be done 55 * external to the Logging APIs, through whatever mechanism is supported by 56 * that system.</p> 57 * 58 * <p style="color: #E40; font-weight: bold;">Please note that this interface is identical to that found in JCL 1.0.4.</p> 59 * 60 * @author <a href="mailto:sanders@apache.org">Scott Sanders</a> 61 * @author Rod Waldhoff 62 * @version $Id: Log.java,v 1.19 2004/06/06 21:16:04 rdonkin Exp $ 63 */ 64 public interface Log { 65 66 67 // ----------------------------------------------------- Logging Properties 68 69 70 /** 71 * <p> Is debug logging currently enabled? </p> 72 * 73 * <p> Call this method to prevent having to perform expensive operations 74 * (for example, <code>String</code> concatenation) 75 * when the log level is more than debug. </p> 76 */ 77 public boolean isDebugEnabled(); 78 79 80 /** 81 * <p> Is error logging currently enabled? </p> 82 * 83 * <p> Call this method to prevent having to perform expensive operations 84 * (for example, <code>String</code> concatenation) 85 * when the log level is more than error. </p> 86 */ 87 public boolean isErrorEnabled(); 88 89 90 /** 91 * <p> Is fatal logging currently enabled? </p> 92 * 93 * <p> Call this method to prevent having to perform expensive operations 94 * (for example, <code>String</code> concatenation) 95 * when the log level is more than fatal. </p> 96 */ 97 public boolean isFatalEnabled(); 98 99 100 /** 101 * <p> Is info logging currently enabled? </p> 102 * 103 * <p> Call this method to prevent having to perform expensive operations 104 * (for example, <code>String</code> concatenation) 105 * when the log level is more than info. </p> 106 */ 107 public boolean isInfoEnabled(); 108 109 110 /** 111 * <p> Is trace logging currently enabled? </p> 112 * 113 * <p> Call this method to prevent having to perform expensive operations 114 * (for example, <code>String</code> concatenation) 115 * when the log level is more than trace. </p> 116 */ 117 public boolean isTraceEnabled(); 118 119 120 /** 121 * <p> Is warn logging currently enabled? </p> 122 * 123 * <p> Call this method to prevent having to perform expensive operations 124 * (for example, <code>String</code> concatenation) 125 * when the log level is more than warn. </p> 126 */ 127 public boolean isWarnEnabled(); 128 129 130 // -------------------------------------------------------- Logging Methods 131 132 133 /** 134 * <p> Log a message with trace log level. </p> 135 * 136 * @param message log this message 137 */ 138 public void trace(Object message); 139 140 141 /** 142 * <p> Log an error with trace log level. </p> 143 * 144 * @param message log this message 145 * @param t log this cause 146 */ 147 public void trace(Object message, Throwable t); 148 149 150 /** 151 * <p> Log a message with debug log level. </p> 152 * 153 * @param message log this message 154 */ 155 public void debug(Object message); 156 157 158 /** 159 * <p> Log an error with debug log level. </p> 160 * 161 * @param message log this message 162 * @param t log this cause 163 */ 164 public void debug(Object message, Throwable t); 165 166 167 /** 168 * <p> Log a message with info log level. </p> 169 * 170 * @param message log this message 171 */ 172 public void info(Object message); 173 174 175 /** 176 * <p> Log an error with info log level. </p> 177 * 178 * @param message log this message 179 * @param t log this cause 180 */ 181 public void info(Object message, Throwable t); 182 183 184 /** 185 * <p> Log a message with warn log level. </p> 186 * 187 * @param message log this message 188 */ 189 public void warn(Object message); 190 191 192 /** 193 * <p> Log an error with warn log level. </p> 194 * 195 * @param message log this message 196 * @param t log this cause 197 */ 198 public void warn(Object message, Throwable t); 199 200 201 /** 202 * <p> Log a message with error log level. </p> 203 * 204 * @param message log this message 205 */ 206 public void error(Object message); 207 208 209 /** 210 * <p> Log an error with error log level. </p> 211 * 212 * @param message log this message 213 * @param t log this cause 214 */ 215 public void error(Object message, Throwable t); 216 217 218 /** 219 * <p> Log a message with fatal log level. </p> 220 * 221 * @param message log this message 222 */ 223 public void fatal(Object message); 224 225 226 /** 227 * <p> Log an error with fatal log level. </p> 228 * 229 * @param message log this message 230 * @param t log this cause 231 */ 232 public void fatal(Object message, Throwable t); 233 234 235 }