Java tutorial
package com.derbysoft.common.log4j; /* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import org.apache.commons.lang3.time.FastDateFormat; import org.apache.log4j.FileAppender; import org.apache.log4j.Layout; import org.apache.log4j.helpers.LogLog; import org.apache.log4j.spi.LoggingEvent; import java.io.File; import java.io.IOException; import java.io.InterruptedIOException; import java.text.SimpleDateFormat; import java.util.Date; import java.util.Locale; import java.util.TimeZone; /** * DailyRollingFileAppender extends {@link org.apache.log4j.FileAppender} so that the * underlying file is rolled over at a user chosen frequency. * <p/> * DailyRollingFileAppender has been observed to exhibit * synchronization issues and data loss. The log4j extras * companion includes alternatives which should be considered * for new deployments and which are discussed in the documentation * for org.apache.log4j.rolling.RollingFileAppender. * <p/> * <p>The rolling schedule is specified by the <b>DatePattern</b> * option. This pattern should follow the {@link java.text.SimpleDateFormat} * conventions. In particular, you <em>must</em> escape literal text * within a pair of single quotes. A formatted version of the date * pattern is used as the suffix for the rolled file name. * <p/> * <p>For example, if the <b>File</b> option is set to * <code>/foo/bar.log</code> and the <b>DatePattern</b> set to * <code>'.'yyyy-MM-dd</code>, on 2001-02-16 at midnight, the logging * file <code>/foo/bar.log</code> will be copied to * <code>/foo/bar.log.2001-02-16</code> and logging for 2001-02-17 * will continue in <code>/foo/bar.log</code> until it rolls over * the next day. * <p/> * <p>Is is possible to specify monthly, weekly, half-daily, daily, * hourly, or minutely rollover schedules. * <p/> * <p><table border="1" cellpadding="2"> * <tr> * <th>DatePattern</th> * <th>Rollover schedule</th> * <th>Example</th> * <p/> * <tr> * <td><code>'.'yyyy-MM</code> * <td>Rollover at the beginning of each month</td> * <p/> * <td>At midnight of May 31st, 2002 <code>/foo/bar.log</code> will be * copied to <code>/foo/bar.log.2002-05</code>. Logging for the month * of June will be output to <code>/foo/bar.log</code> until it is * also rolled over the next month. * <p/> * <tr> * <td><code>'.'yyyy-ww</code> * <p/> * <td>Rollover at the first day of each week. The first day of the * week depends on the locale.</td> * <p/> * <td>Assuming the first day of the week is Sunday, on Saturday * midnight, June 9th 2002, the file <i>/foo/bar.log</i> will be * copied to <i>/foo/bar.log.2002-23</i>. Logging for the 24th week * of 2002 will be output to <code>/foo/bar.log</code> until it is * rolled over the next week. * <p/> * <tr> * <td><code>'.'yyyy-MM-dd</code> * <p/> * <td>Rollover at midnight each day.</td> * <p/> * <td>At midnight, on March 8th, 2002, <code>/foo/bar.log</code> will * be copied to <code>/foo/bar.log.2002-03-08</code>. Logging for the * 9th day of March will be output to <code>/foo/bar.log</code> until * it is rolled over the next day. * <p/> * <tr> * <td><code>'.'yyyy-MM-dd-a</code> * <p/> * <td>Rollover at midnight and midday of each day.</td> * <p/> * <td>At noon, on March 9th, 2002, <code>/foo/bar.log</code> will be * copied to <code>/foo/bar.log.2002-03-09-AM</code>. Logging for the * afternoon of the 9th will be output to <code>/foo/bar.log</code> * until it is rolled over at midnight. * <p/> * <tr> * <td><code>'.'yyyy-MM-dd-HH</code> * <p/> * <td>Rollover at the top of every hour.</td> * <p/> * <td>At approximately 11:00.000 o'clock on March 9th, 2002, * <code>/foo/bar.log</code> will be copied to * <code>/foo/bar.log.2002-03-09-10</code>. Logging for the 11th hour * of the 9th of March will be output to <code>/foo/bar.log</code> * until it is rolled over at the beginning of the next hour. * <p/> * <p/> * <tr> * <td><code>'.'yyyy-MM-dd-HH-mm</code> * <p/> * <td>Rollover at the beginning of every minute.</td> * <p/> * <td>At approximately 11:23,000, on March 9th, 2001, * <code>/foo/bar.log</code> will be copied to * <code>/foo/bar.log.2001-03-09-10-22</code>. Logging for the minute * of 11:23 (9th of March) will be output to * <code>/foo/bar.log</code> until it is rolled over the next minute. * <p/> * </table> * <p/> * <p>Do not use the colon ":" character in anywhere in the * <b>DatePattern</b> option. The text before the colon is interpeted * as the protocol specificaion of a URL which is probably not what * you want. * * @author Eirik Lygre * @author Ceki Gülcü */ public class DailyRollingFileAppender extends FileAppender { // The code assumes that the following constants are in a increasing // sequence. static final int TOP_OF_TROUBLE = -1; static final int TOP_OF_MINUTE = 0; static final int TOP_OF_HOUR = 1; static final int HALF_DAY = 2; static final int TOP_OF_DAY = 3; static final int TOP_OF_WEEK = 4; static final int TOP_OF_MONTH = 5; /** * The date pattern. By default, the pattern is set to * "'.'yyyy-MM-dd" meaning daily rollover. */ private String datePattern = "'.'yyyy-MM-dd"; /** * The log file will be renamed to the value of the * scheduledFilename variable when the next interval is entered. For * example, if the rollover period is one hour, the log file will be * renamed to the value of "scheduledFilename" at the beginning of * the next hour. * <p/> * The precise time when a rollover occurs depends on logging * activity. */ private String scheduledFilename; /** * The next time we estimate a rollover should occur. */ private long nextCheck = System.currentTimeMillis() - 1; private Date now = new Date(); private FastDateFormat sdf; // The gmtTimeZone is used only in computeCheckPeriod() method. private String timeZoneID = "UTC"; private TimeZone timeZone = TimeZone.getTimeZone(timeZoneID); private RollingCalendar rc = new RollingCalendar(timeZone, Locale.getDefault()); private int checkPeriod = TOP_OF_TROUBLE; /** * The default constructor does nothing. */ public DailyRollingFileAppender() { } /** * Instantiate a <code>DailyRollingFileAppender</code> and open the * file designated by <code>filename</code>. The opened filename will * become the ouput destination for this appender. */ public DailyRollingFileAppender(Layout layout, String filename, String datePattern) throws IOException { super(layout, filename, true); this.datePattern = datePattern; activateOptions(); } /** * The <b>DatePattern</b> takes a string in the same format as * expected by {@link java.text.SimpleDateFormat}. This options determines the * rollover schedule. */ public void setDatePattern(String pattern) { datePattern = pattern; } /** * Returns the value of the <b>DatePattern</b> option. */ public String getDatePattern() { return datePattern; } public String getTimeZoneID() { return timeZoneID; } public void setTimeZoneID(String timeZoneID) { this.timeZoneID = timeZoneID; timeZone = TimeZone.getTimeZone(timeZoneID); } public void activateOptions() { super.activateOptions(); if (datePattern != null && fileName != null) { now.setTime(System.currentTimeMillis()); sdf = FastDateFormat.getInstance(datePattern, timeZone, Locale.getDefault()); int type = computeCheckPeriod(); printPeriodicity(type); rc.setType(type); File file = new File(fileName); scheduledFilename = fileName + sdf.format(new Date(file.lastModified())); } else { LogLog.error("Either File or DatePattern options are not set for appender [" + name + "]."); } } void printPeriodicity(int type) { switch (type) { case TOP_OF_MINUTE: LogLog.debug("Appender [" + name + "] to be rolled every minute."); break; case TOP_OF_HOUR: LogLog.debug("Appender [" + name + "] to be rolled on top of every hour."); break; case HALF_DAY: LogLog.debug("Appender [" + name + "] to be rolled at midday and midnight."); break; case TOP_OF_DAY: LogLog.debug("Appender [" + name + "] to be rolled at midnight."); break; case TOP_OF_WEEK: LogLog.debug("Appender [" + name + "] to be rolled at start of week."); break; case TOP_OF_MONTH: LogLog.debug("Appender [" + name + "] to be rolled at start of every month."); break; default: LogLog.warn("Unknown periodicity for appender [" + name + "]."); } } // This method computes the roll over period by looping over the // periods, starting with the shortest, and stopping when the r0 is // different from from r1, where r0 is the epoch formatted according // the datePattern (supplied by the user) and r1 is the // epoch+nextMillis(i) formatted according to datePattern. All date // formatting is done in GMT and not local format because the test // logic is based on comparisons relative to 1970-01-01 00:00:00 // GMT (the epoch). int computeCheckPeriod() { RollingCalendar rollingCalendar = new RollingCalendar(timeZone, Locale.getDefault()); // set sate to 1970-01-01 00:00:00 GMT Date epoch = new Date(0); if (datePattern != null) { for (int i = TOP_OF_MINUTE; i <= TOP_OF_MONTH; i++) { SimpleDateFormat simpleDateFormat = new SimpleDateFormat(datePattern); simpleDateFormat.setTimeZone(timeZone); // do all date formatting in GMT String r0 = simpleDateFormat.format(epoch); rollingCalendar.setType(i); Date next = new Date(rollingCalendar.getNextCheckMillis(epoch)); String r1 = simpleDateFormat.format(next); //System.out.println("Type = "+i+", r0 = "+r0+", r1 = "+r1); if (r0 != null && r1 != null && !r0.equals(r1)) { return i; } } } return TOP_OF_TROUBLE; // Deliberately head for trouble... } /** * Rollover the current file to a new file. */ void rollOver() throws IOException { /* Compute filename, but only if datePattern is specified */ if (datePattern == null) { errorHandler.error("Missing DatePattern option in rollOver()."); return; } String datedFilename = fileName + sdf.format(now); // It is too early to roll over because we are still within the // bounds of the current interval. Rollover will occur once the // next interval is reached. if (scheduledFilename.equals(datedFilename)) { return; } // close current file, and rename it to datedFilename this.closeFile(); File target = new File(scheduledFilename); if (target.exists()) { if (!target.delete()) { LogLog.error("Failed to delete [" + scheduledFilename + "]."); } } File file = new File(fileName); boolean result = file.renameTo(target); if (result) { LogLog.debug(fileName + " -> " + scheduledFilename); } else { LogLog.error("Failed to rename [" + fileName + "] to [" + scheduledFilename + "]."); } try { // This will also close the file. This is OK since multiple // close operations are safe. this.setFile(fileName, true, this.bufferedIO, this.bufferSize); } catch (IOException e) { errorHandler.error("setFile(" + fileName + ", true) call failed."); } scheduledFilename = datedFilename; } /** * This method differentiates DailyRollingFileAppender from its * super class. * <p/> * <p>Before actually logging, this method will check whether it is * time to do a rollover. If it is, it will schedule the next * rollover time and then rollover. */ protected void subAppend(LoggingEvent event) { long n = System.currentTimeMillis(); if (n >= nextCheck) { now.setTime(n); nextCheck = rc.getNextCheckMillis(now); try { rollOver(); } catch (IOException ioe) { if (ioe instanceof InterruptedIOException) { Thread.currentThread().interrupt(); } LogLog.error("rollOver() failed.", ioe); } } super.subAppend(event); } }