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 * <p>A simple logging interface abstracting logging APIs. In order to be 21 * instantiated successfully by {@link LogFactory}, classes that implement 22 * this interface must have a constructor that takes a single String 23 * parameter representing the "name" of this Log.</p> 24 * 25 * <p> The six logging levels used by <code>Log</code> are (in order): 26 * <ol> 27 * <li>trace (the least serious)</li> 28 * <li>debug</li> 29 * <li>info</li> 30 * <li>warn</li> 31 * <li>error</li> 32 * <li>fatal (the most serious)</li> 33 * </ol> 34 * The mapping of these log levels to the concepts used by the underlying 35 * logging system is implementation dependent. 36 * The implementation should ensure, though, that this ordering behaves 37 * as expected.</p> 38 * 39 * <p>Performance is often a logging concern. 40 * By examining the appropriate property, 41 * a component can avoid expensive operations (producing information 42 * to be logged).</p> 43 * 44 * <p> For example, 45 * <code><pre> 46 * if (log.isDebugEnabled()) { 47 * ... do something expensive ... 48 * log.debug(theResult); 49 * } 50 * </pre></code> 51 * </p> 52 * 53 * <p>Configuration of the underlying logging system will generally be done 54 * external to the Logging APIs, through whatever mechanism is supported by 55 * that system.</p> 56 * 57 * <p style="color: #E40; font-weight: bold;">Please note that this interface is identical to that found in JCL 1.1.1.</p> 58 * 59 * @author <a href="mailto:sanders (at) apache.org">Scott Sanders</a> 60 * @author Rod Waldhoff 61 * @version $Id: Log.java,v 1.19 2004/06/06 21:16:04 rdonkin Exp $ 62 */ 63 public interface Log { 64 65 // ----------------------------------------------------- Logging Properties 66 67 /** 68 * <p> Is debug logging currently enabled? </p> 69 * 70 * <p> Call this method to prevent having to perform expensive operations 71 * (for example, <code>String</code> concatenation) 72 * when the log level is more than debug. </p> 73 */ 74 public boolean isDebugEnabled(); 75 76 /** 77 * <p> Is error logging currently enabled? </p> 78 * 79 * <p> Call this method to prevent having to perform expensive operations 80 * (for example, <code>String</code> concatenation) 81 * when the log level is more than error. </p> 82 */ 83 public boolean isErrorEnabled(); 84 85 /** 86 * <p> Is fatal logging currently enabled? </p> 87 * 88 * <p> Call this method to prevent having to perform expensive operations 89 * (for example, <code>String</code> concatenation) 90 * when the log level is more than fatal. </p> 91 */ 92 public boolean isFatalEnabled(); 93 94 /** 95 * <p> Is info logging currently enabled? </p> 96 * 97 * <p> Call this method to prevent having to perform expensive operations 98 * (for example, <code>String</code> concatenation) 99 * when the log level is more than info. </p> 100 * 101 * @return true if info enabled, false otherwise 102 */ 103 public boolean isInfoEnabled(); 104 105 /** 106 * <p> Is trace logging currently enabled? </p> 107 * 108 * <p> Call this method to prevent having to perform expensive operations 109 * (for example, <code>String</code> concatenation) 110 * when the log level is more than trace. </p> 111 * 112 * @return true if trace enabled, false otherwise 113 */ 114 public boolean isTraceEnabled(); 115 116 /** 117 * <p> Is warn logging currently enabled? </p> 118 * 119 * <p> Call this method to prevent having to perform expensive operations 120 * (for example, <code>String</code> concatenation) 121 * when the log level is more than warn. </p> 122 */ 123 public boolean isWarnEnabled(); 124 125 // -------------------------------------------------------- Logging Methods 126 127 /** 128 * <p> Log a message with trace log level. </p> 129 * 130 * @param message log this message 131 */ 132 public void trace(Object message); 133 134 /** 135 * <p> Log an error with trace log level. </p> 136 * 137 * @param message log this message 138 * @param t log this cause 139 */ 140 public void trace(Object message, Throwable t); 141 142 /** 143 * <p> Log a message with debug log level. </p> 144 * 145 * @param message log this message 146 */ 147 public void debug(Object message); 148 149 /** 150 * <p> Log an error with debug log level. </p> 151 * 152 * @param message log this message 153 * @param t log this cause 154 */ 155 public void debug(Object message, Throwable t); 156 157 /** 158 * <p> Log a message with info log level. </p> 159 * 160 * @param message log this message 161 */ 162 public void info(Object message); 163 164 /** 165 * <p> Log an error with info log level. </p> 166 * 167 * @param message log this message 168 * @param t log this cause 169 */ 170 public void info(Object message, Throwable t); 171 172 /** 173 * <p> Log a message with warn log level. </p> 174 * 175 * @param message log this message 176 */ 177 public void warn(Object message); 178 179 /** 180 * <p> Log an error with warn log level. </p> 181 * 182 * @param message log this message 183 * @param t log this cause 184 */ 185 public void warn(Object message, Throwable t); 186 187 /** 188 * <p> Log a message with error log level. </p> 189 * 190 * @param message log this message 191 */ 192 public void error(Object message); 193 194 /** 195 * <p> Log an error with error log level. </p> 196 * 197 * @param message log this message 198 * @param t log this cause 199 */ 200 public void error(Object message, Throwable t); 201 202 /** 203 * <p> Log a message with fatal log level. </p> 204 * 205 * @param message log this message 206 */ 207 public void fatal(Object message); 208 209 /** 210 * <p> Log an error with fatal log level. </p> 211 * 212 * @param message log this message 213 * @param t log this cause 214 */ 215 public void fatal(Object message, Throwable t); 216 217 } 218
