1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package org.apache.log4j; 19 20 import org.apache.log4j.helpers.OptionConverter; 21 import org.apache.log4j.helpers.PatternConverter; 22 import org.apache.log4j.pattern.BridgePatternConverter; 23 import org.apache.log4j.spi.LoggingEvent; 24 25 26 // Contributors: Nelson Minar <nelson@monkey.org> 27 // Anders Kristensen <akristensen@dynamicsoft.com> 28 29 /** 30 * This class is an enhanced version of org.apache.log4j.PatternLayout 31 * which was originally developed as part of the abandoned log4j 1.3 32 * effort and has been available in the extras companion. 33 * This pattern layout should be used in preference to 34 * org.apache.log4j.PatternLayout except when compatibility 35 * where PatternLayout has been extended either through subclassing 36 * or alternative pattern parsers. 37 * 38 * 39 * <p>A flexible layout configurable with pattern string. The goal of this class 40 * is to {@link #format format} a {@link LoggingEvent} and return the results 41 * in a {@link StringBuffer}. The format of the result depends on the 42 * <em>conversion pattern</em>. 43 * <p> 44 * 45 * <p>The conversion pattern is closely related to the conversion 46 * pattern of the printf function in C. A conversion pattern is 47 * composed of literal text and format control expressions called 48 * <em>conversion specifiers</em>. 49 * 50 * <p><i>Note that you are free to insert any literal text within the 51 * conversion pattern.</i> 52 * </p> 53 54 <p>Each conversion specifier starts with a percent sign (%) and is 55 followed by optional <em>format modifiers</em> and a <em>conversion 56 character</em>. The conversion character specifies the type of 57 data, e.g. category, priority, date, thread name. The format 58 modifiers control such things as field width, padding, left and 59 right justification. The following is a simple example. 60 61 <p>Let the conversion pattern be <b>"%-5p [%t]: %m%n"</b> and assume 62 that the log4j environment was set to use a EnhancedPatternLayout. Then the 63 statements 64 <pre> 65 Category root = Category.getRoot(); 66 root.debug("Message 1"); 67 root.warn("Message 2"); 68 </pre> 69 would yield the output 70 <pre> 71 DEBUG [main]: Message 1 72 WARN [main]: Message 2 73 </pre> 74 75 <p>Note that there is no explicit separator between text and 76 conversion specifiers. The pattern parser knows when it has reached 77 the end of a conversion specifier when it reads a conversion 78 character. In the example above the conversion specifier 79 <b>%-5p</b> means the priority of the logging event should be left 80 justified to a width of five characters. 81 82 The recognized conversion characters are 83 84 <p> 85 <table border="1" CELLPADDING="8"> 86 <th>Conversion Character</th> 87 <th>Effect</th> 88 89 <tr> 90 <td align=center><b>c</b></td> 91 92 <td>Used to output the category of the logging event. The 93 category conversion specifier can be optionally followed by 94 NameAbbreviator pattern. 95 96 <p>For example, for the category name "alpha.beta.gamma" the pattern 97 <b>%c{2}</b> will output the last two elements ("beta.gamma"), 98 <b>%c{-2}</b> will remove two elements leaving "gamma", 99 <b>%c{1.}</b> will output "a.b.gamma". 100 101 </td> 102 </tr> 103 104 <tr> 105 <td align=center><b>C</b></td> 106 107 <td>Used to output the fully qualified class name of the caller 108 issuing the logging request. This conversion specifier 109 can be optionally followed by <em>precision specifier</em>, that 110 is a decimal constant in brackets. 111 112 <td>Used to output the category of the logging event. The 113 category conversion specifier can be optionally followed by 114 NameAbbreviator pattern. 115 116 <p>For example, for the category name "alpha.beta.gamma" the pattern 117 <b>%c{2}</b> will output the last two elements ("beta.gamma"), 118 <b>%c{-2}</b> will remove two elements leaving "gamma", 119 <b>%c{1.}</b> will output "a.b.gamma". 120 121 <p><b>WARNING</b> Generating the caller class information is 122 slow. Thus, its use should be avoided unless execution speed is 123 not an issue. 124 125 </td> 126 </tr> 127 128 <tr> <td align=center><b>d</b></td> <td>Used to output the date of 129 the logging event. The date conversion specifier may be 130 followed by a set of braces containing a 131 date and time pattern strings {@link java.text.SimpleDateFormat}, 132 <em>ABSOLUTE</em>, <em>DATE</em> or <em>ISO8601</em> 133 and a set of braces containing a time zone id per 134 {@link java.util.TimeZone#getTimeZone(String)}. 135 For example, <b>%d{HH:mm:ss,SSS}</b>, 136 <b>%d{dd MMM yyyy HH:mm:ss,SSS}</b>, 137 <b>%d{DATE}</b> or <b>%d{HH:mm:ss}{GMT+0}</b>. If no date format specifier is given then 138 ISO8601 format is assumed. 139 </td> 140 </tr> 141 142 <tr> 143 <td align=center><b>F</b></td> 144 145 <td>Used to output the file name where the logging request was 146 issued. 147 148 <p><b>WARNING</b> Generating caller location information is 149 extremely slow and should be avoided unless execution speed 150 is not an issue. 151 152 </tr> 153 154 <tr> 155 <td align=center><b>l</b></td> 156 157 <td>Used to output location information of the caller which generated 158 the logging event. 159 160 <p>The location information depends on the JVM implementation but 161 usually consists of the fully qualified name of the calling 162 method followed by the callers source the file name and line 163 number between parentheses. 164 165 <p>The location information can be very useful. However, its 166 generation is <em>extremely</em> slow and should be avoided 167 unless execution speed is not an issue. 168 169 </td> 170 </tr> 171 172 <tr> 173 <td align=center><b>L</b></td> 174 175 <td>Used to output the line number from where the logging request 176 was issued. 177 178 <p><b>WARNING</b> Generating caller location information is 179 extremely slow and should be avoided unless execution speed 180 is not an issue. 181 182 </tr> 183 184 185 <tr> 186 <td align=center><b>m</b></td> 187 <td>Used to output the application supplied message associated with 188 the logging event.</td> 189 </tr> 190 191 <tr> 192 <td align=center><b>M</b></td> 193 194 <td>Used to output the method name where the logging request was 195 issued. 196 197 <p><b>WARNING</b> Generating caller location information is 198 extremely slow and should be avoided unless execution speed 199 is not an issue. 200 201 </tr> 202 203 <tr> 204 <td align=center><b>n</b></td> 205 206 <td>Outputs the platform dependent line separator character or 207 characters. 208 209 <p>This conversion character offers practically the same 210 performance as using non-portable line separator strings such as 211 "\n", or "\r\n". Thus, it is the preferred way of specifying a 212 line separator. 213 214 215 </tr> 216 217 <tr> 218 <td align=center><b>p</b></td> 219 <td>Used to output the priority of the logging event.</td> 220 </tr> 221 222 <tr> 223 224 <td align=center><b>r</b></td> 225 226 <td>Used to output the number of milliseconds elapsed since the construction 227 of the layout until the creation of the logging event.</td> 228 </tr> 229 230 231 <tr> 232 <td align=center><b>t</b></td> 233 234 <td>Used to output the name of the thread that generated the 235 logging event.</td> 236 237 </tr> 238 239 <tr> 240 241 <td align=center><b>x</b></td> 242 243 <td>Used to output the NDC (nested diagnostic context) associated 244 with the thread that generated the logging event. 245 </td> 246 </tr> 247 248 249 <tr> 250 <td align=center><b>X</b></td> 251 252 <td> 253 254 <p>Used to output the MDC (mapped diagnostic context) associated 255 with the thread that generated the logging event. The <b>X</b> 256 conversion character can be followed by the key for the 257 map placed between braces, as in <b>%X{clientNumber}</b> where 258 <code>clientNumber</code> is the key. The value in the MDC 259 corresponding to the key will be output. If no additional sub-option 260 is specified, then the entire contents of the MDC key value pair set 261 is output using a format {{key1,val1},{key2,val2}}</p> 262 263 <p>See {@link MDC} class for more details. 264 </p> 265 266 </td> 267 </tr> 268 269 <tr> 270 <td align=center><b>properties</b></td> 271 272 <td> 273 <p>Used to output the Properties associated 274 with the logging event. The <b>properties</b> 275 conversion word can be followed by the key for the 276 map placed between braces, as in <b>%properties{application}</b> where 277 <code>application</code> is the key. The value in the Properties bundle 278 corresponding to the key will be output. If no additional sub-option 279 is specified, then the entire contents of the Properties key value pair set 280 is output using a format {{key1,val1},{key2,val2}}</p> 281 </td> 282 </tr> 283 284 <tr> 285 <td align=center><b>throwable</b></td> 286 287 <td> 288 <p>Used to output the Throwable trace that has been bound to the LoggingEvent, by 289 default this will output the full trace as one would normally 290 find by a call to Throwable.printStackTrace(). 291 <b>%throwable{short}</b> or <b>%throwable{1}</b> will output the first line of 292 stack trace. <b>throwable{none}</b> or <b>throwable{0}</b> will suppress 293 the stack trace. <b>%throwable{n}</b> will output n lines of stack trace 294 if a positive integer or omit the last -n lines if a negative integer. 295 If no %throwable pattern is specified, the appender will take 296 responsibility to output the stack trace as it sees fit.</p> 297 </td> 298 </tr> 299 300 <tr> 301 302 <td align=center><b>%</b></td> 303 304 <td>The sequence %% outputs a single percent sign. 305 </td> 306 </tr> 307 308 </table> 309 310 <p>By default the relevant information is output as is. However, 311 with the aid of format modifiers it is possible to change the 312 minimum field width, the maximum field width and justification. 313 314 <p>The optional format modifier is placed between the percent sign 315 and the conversion character. 316 317 <p>The first optional format modifier is the <em>left justification 318 flag</em> which is just the minus (-) character. Then comes the 319 optional <em>minimum field width</em> modifier. This is a decimal 320 constant that represents the minimum number of characters to 321 output. If the data item requires fewer characters, it is padded on 322 either the left or the right until the minimum width is 323 reached. The default is to pad on the left (right justify) but you 324 can specify right padding with the left justification flag. The 325 padding character is space. If the data item is larger than the 326 minimum field width, the field is expanded to accommodate the 327 data. The value is never truncated. 328 329 <p>This behavior can be changed using the <em>maximum field 330 width</em> modifier which is designated by a period followed by a 331 decimal constant. If the data item is longer than the maximum 332 field, then the extra characters are removed from the 333 <em>beginning</em> of the data item and not from the end. For 334 example, it the maximum field width is eight and the data item is 335 ten characters long, then the first two characters of the data item 336 are dropped. This behavior deviates from the printf function in C 337 where truncation is done from the end. 338 339 <p>Below are various format modifier examples for the category 340 conversion specifier. 341 342 <p> 343 <TABLE BORDER=1 CELLPADDING=8> 344 <th>Format modifier 345 <th>left justify 346 <th>minimum width 347 <th>maximum width 348 <th>comment 349 350 <tr> 351 <td align=center>%20c</td> 352 <td align=center>false</td> 353 <td align=center>20</td> 354 <td align=center>none</td> 355 356 <td>Left pad with spaces if the category name is less than 20 357 characters long. 358 359 <tr> <td align=center>%-20c</td> <td align=center>true</td> <td 360 align=center>20</td> <td align=center>none</td> <td>Right pad with 361 spaces if the category name is less than 20 characters long. 362 363 <tr> 364 <td align=center>%.30c</td> 365 <td align=center>NA</td> 366 <td align=center>none</td> 367 <td align=center>30</td> 368 369 <td>Truncate from the beginning if the category name is longer than 30 370 characters. 371 372 <tr> 373 <td align=center>%20.30c</td> 374 <td align=center>false</td> 375 <td align=center>20</td> 376 <td align=center>30</td> 377 378 <td>Left pad with spaces if the category name is shorter than 20 379 characters. However, if category name is longer than 30 characters, 380 then truncate from the beginning. 381 382 <tr> 383 <td align=center>%-20.30c</td> 384 <td align=center>true</td> 385 <td align=center>20</td> 386 <td align=center>30</td> 387 388 <td>Right pad with spaces if the category name is shorter than 20 389 characters. However, if category name is longer than 30 characters, 390 then truncate from the beginning. 391 392 </table> 393 394 <p>Below are some examples of conversion patterns. 395 396 <dl> 397 398 <p><dt><b>%r [%t] %-5p %c %x - %m%n</b> 399 <p><dd>This is essentially the TTCC layout. 400 401 <p><dt><b>%-6r [%15.15t] %-5p %30.30c %x - %m%n</b> 402 403 <p><dd>Similar to the TTCC layout except that the relative time is 404 right padded if less than 6 digits, thread name is right padded if 405 less than 15 characters and truncated if longer and the category 406 name is left padded if shorter than 30 characters and truncated if 407 longer. 408 409 </dl> 410 411 <p>The above text is largely inspired from Peter A. Darnell and 412 Philip E. Margolis' highly recommended book "C -- a Software 413 Engineering Approach", ISBN 0-387-97389-3. 414 415 @author <a href="mailto:cakalijp@Maritz.com">James P. Cakalic</a> 416 @author Ceki Gülcü 417 418 419 @since 1.2.16 */ 420 public class EnhancedPatternLayout extends Layout { 421 /** Default pattern string for log output. Currently set to the 422 string <b>"%m%n"</b> which just prints the application supplied 423 message. */ 424 public static final String DEFAULT_CONVERSION_PATTERN = "%m%n"; 425 426 /** A conversion pattern equivalent to the TTCCCLayout. 427 Current value is <b>%r [%t] %p %c %x - %m%n</b>. */ 428 public static final String TTCC_CONVERSION_PATTERN = 429 "%r [%t] %p %c %x - %m%n"; 430 431 /** 432 * Initial size of internal buffer, no longer used. 433 * @deprecated since 1.3 434 */ 435 protected final int BUF_SIZE = 256; 436 437 /** 438 * Maximum capacity of internal buffer, no longer used. 439 * @deprecated since 1.3 440 */ 441 protected final int MAX_CAPACITY = 1024; 442 443 /** 444 * Customized pattern conversion rules are stored under this key in the 445 * {@link org.apache.log4j.spi.LoggerRepository LoggerRepository} object store. 446 */ 447 public static final String PATTERN_RULE_REGISTRY = "PATTERN_RULE_REGISTRY"; 448 449 450 /** 451 * Initial converter for pattern. 452 */ 453 private PatternConverter head; 454 455 /** 456 * Conversion pattern. 457 */ 458 private String conversionPattern; 459 460 /** 461 * True if any element in pattern formats information from exceptions. 462 */ 463 private boolean handlesExceptions; 464 465 /** 466 Constructs a EnhancedPatternLayout using the DEFAULT_LAYOUT_PATTERN. 467 468 The default pattern just produces the application supplied message. 469 */ 470 public EnhancedPatternLayout() { 471 this(DEFAULT_CONVERSION_PATTERN); 472 } 473 474 /** 475 * Constructs a EnhancedPatternLayout using the supplied conversion pattern. 476 * @param pattern conversion pattern. 477 */ 478 public EnhancedPatternLayout(final String pattern) { 479 this.conversionPattern = pattern; 480 head = createPatternParser( 481 (pattern == null) ? DEFAULT_CONVERSION_PATTERN : pattern).parse(); 482 if (head instanceof BridgePatternConverter) { 483 handlesExceptions = !((BridgePatternConverter) head).ignoresThrowable(); 484 } else { 485 handlesExceptions = false; 486 } 487 } 488 489 /** 490 * Set the <b>ConversionPattern</b> option. This is the string which 491 * controls formatting and consists of a mix of literal content and 492 * conversion specifiers. 493 * 494 * @param conversionPattern conversion pattern. 495 */ 496 public void setConversionPattern(final String conversionPattern) { 497 this.conversionPattern = 498 OptionConverter.convertSpecialChars(conversionPattern); 499 head = createPatternParser(this.conversionPattern).parse(); 500 if (head instanceof BridgePatternConverter) { 501 handlesExceptions = !((BridgePatternConverter) head).ignoresThrowable(); 502 } else { 503 handlesExceptions = false; 504 } 505 } 506 507 /** 508 * Returns the value of the <b>ConversionPattern</b> option. 509 * @return conversion pattern. 510 */ 511 public String getConversionPattern() { 512 return conversionPattern; 513 } 514 515 516 /** 517 Returns PatternParser used to parse the conversion string. Subclasses 518 may override this to return a subclass of PatternParser which recognize 519 custom conversion characters. 520 521 @since 0.9.0 522 */ 523 protected org.apache.log4j.helpers.PatternParser createPatternParser(String pattern) { 524 return new org.apache.log4j.pattern.BridgePatternParser(pattern); 525 } 526 527 528 /** 529 Activates the conversion pattern. Do not forget to call this method after 530 you change the parameters of the EnhancedPatternLayout instance. 531 */ 532 public void activateOptions() { 533 // nothing to do. 534 } 535 536 537 /** 538 * Formats a logging event to a writer. 539 * @param event logging event to be formatted. 540 */ 541 public String format(final LoggingEvent event) { 542 StringBuffer buf = new StringBuffer(); 543 for(PatternConverter c = head; 544 c != null; 545 c = c.next) { 546 c.format(buf, event); 547 } 548 return buf.toString(); 549 } 550 551 /** 552 * Will return false if any of the conversion specifiers in the pattern 553 * handles {@link Exception Exceptions}. 554 * @return true if the pattern formats any information from exceptions. 555 */ 556 public boolean ignoresThrowable() { 557 return !handlesExceptions; 558 } 559 }