Custom DailyRollingFileAppender with MaxBackupIndex

http://wiki.apache.org/logging-log4j/DailyRollingFileAppender

DailyRollingFileAppender是不支持最大备份数设置的（RollingFileAppender支持该属性，但是又不能按时间滚动），为了达到这个目的而又不想单独写个定时脚本去手动清理日志目录，我们必须自定义一个DailyRollingFileAppender 以支持MaxBackupIndex属性。

package org.apache.log4j;

/*
* Copyright 1999-2005 The Apache Software Foundation.
*
* Licensed 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 java.io.IOException;
import java.io.File;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Calendar;
import java.util.TimeZone;
import java.util.Locale;

import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.spi.LoggingEvent;

/**
* DailyMaxRollingFileAppender extends {@link FileAppender} so that the
* underlying file is rolled over at a user chosen frequency.
* <p/>
* <p>The rolling schedule is specified by the <b>DatePattern</b>.
* This pattern should follow the {@link 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.
* <p/>
* <p>You have also to define the maximum number of file are kept
* before the oldest is erased.</p>
*
* @author Eirik Lygre
* @author Ceki Gülcü
* @author Riccardo Nicosia;
*/
public class DailyMaxRollingFileAppender 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";

/**
* There is one backup file by default.
*/
private int maxBackupIndex = 1;

/**
* 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;

Date now = new Date();

SimpleDateFormat sdf;

RollingPastCalendar rpc = new RollingPastCalendar();

int checkPeriod = TOP_OF_TROUBLE;

// The gmtTimeZone is used only in computeCheckPeriod() method.
static final TimeZone gmtTimeZone = TimeZone.getTimeZone("GMT");

/**
* The default constructor does nothing.
*/
public DailyMaxRollingFileAppender() {
}

/**
* 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 DailyMaxRollingFileAppender(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 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;
}

/**
* Set the maximum number of backup files to keep around.
* <p/>
* <p>The <b>MaxBackupIndex</b> option determines how many backup
* files are kept before the oldest is erased. This option takes
* a positive integer value. If set to zero, then there will be no
* backup files and the log file will be renamed to the value of the
* scheduledFilename variable when the next interval is entered.
*/
public void setMaxBackupIndex(int maxBackups) {
this.maxBackupIndex = maxBackups;
}

/**
* Returns the value of the <b>MaxBackupIndex</b> option.
*/
public int getMaxBackupIndex() {
return maxBackupIndex;
}

public void activateOptions() {
super.activateOptions();

LogLog.debug("Max backup file kept: " + maxBackupIndex + ".");

if (datePattern != null && fileName != null) {
now.setTime(System.currentTimeMillis());
sdf = new SimpleDateFormat(datePattern);
int type = computeCheckPeriod();
printPeriodicity(type);
rpc.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() {
RollingPastCalendar rollingPastCalendar = new RollingPastCalendar(gmtTimeZone, Locale.ENGLISH);
// 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(gmtTimeZone); // do all date formatting in GMT
String r0 = simpleDateFormat.format(epoch);
rollingPastCalendar.setType(i);
Date next = new Date(rollingPastCalendar.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()) {
target.delete();
}

File file = new File(fileName);
boolean result = file.renameTo(target);
if (result) {
LogLog.debug(fileName + " -> " + scheduledFilename);

// If maxBackups <= 0, then there is no file renaming to be done.
if (maxBackupIndex > 0) {
// Delete the oldest file, to keep Windows happy.
file = new File(fileName + dateBefore());

if (file.exists())
file.delete();
}
} 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, false, this.bufferedIO, this.bufferSize);
} catch (IOException e) {
errorHandler.error("setFile(" + fileName + ", false) call failed.");
}
scheduledFilename = datedFilename;
}

private String dateBefore() {
String dataAnte = "";

if (datePattern != null) {
SimpleDateFormat simpleDateFormat = new SimpleDateFormat(datePattern);

dataAnte = simpleDateFormat.format(new Date(rpc.getPastCheckMillis(new Date(), maxBackupIndex)));
}

return dataAnte;
}

/**
* 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 = rpc.getNextCheckMillis(now);

try {
rollOver();
} catch (IOException ioe) {
LogLog.error("rollOver() failed.", ioe);
}
}

super.subAppend(event);
}

/*
* DEBUG
*/
public static void main(String args[]) {
DailyMaxRollingFileAppender dmrfa = new DailyMaxRollingFileAppender();

dmrfa.setDatePattern("'.'yyyy-MM-dd-HH-mm");

dmrfa.setFile("prova");

System.out.println("dmrfa.getMaxBackupIndex():" + dmrfa.getMaxBackupIndex());

dmrfa.activateOptions();

for (int i = 0; i < 5; i++) {
dmrfa.subAppend(null);

try {
Thread.sleep(60000);
} catch (InterruptedException ex) {
}

System.out.println("Fine attesa");
}
}
}

/**
* RollingPastCalendar is a helper class to DailyMaxRollingFileAppender.
* Given a periodicity type and the current time, it computes the
* past maxBackupIndex date.
*/
class RollingPastCalendar extends RollingCalendar {
RollingPastCalendar() {
super();
}

RollingPastCalendar(TimeZone tz, Locale locale) {
super(tz, locale);
}

public long getPastCheckMillis(Date now, int maxBackupIndex) {
return getPastDate(now, maxBackupIndex).getTime();
}

public Date getPastDate(Date now, int maxBackupIndex) {
this.setTime(now);

switch (type) {
case DailyRollingFileAppender.TOP_OF_MINUTE:
this.set(Calendar.SECOND, this.get(Calendar.SECOND));
this.set(Calendar.MILLISECOND, this.get(Calendar.MILLISECOND));
this.set(Calendar.MINUTE, this.get(Calendar.MINUTE) - maxBackupIndex);
break;

case DailyRollingFileAppender.TOP_OF_HOUR:
this.set(Calendar.MINUTE, this.get(Calendar.MINUTE));
this.set(Calendar.SECOND, this.get(Calendar.SECOND));
this.set(Calendar.MILLISECOND, this.get(Calendar.MILLISECOND));
this.set(Calendar.HOUR_OF_DAY, this.get(Calendar.HOUR_OF_DAY) - maxBackupIndex);
break;

case DailyRollingFileAppender.HALF_DAY:
this.set(Calendar.MINUTE, this.get(Calendar.MINUTE));
this.set(Calendar.SECOND, this.get(Calendar.SECOND));
this.set(Calendar.MILLISECOND, this.get(Calendar.MILLISECOND));
int hour = get(Calendar.HOUR_OF_DAY);
if (hour < 12) {
this.set(Calendar.HOUR_OF_DAY, 12);
} else {
this.set(Calendar.HOUR_OF_DAY, 0);
}
this.set(Calendar.DAY_OF_MONTH, this.get(Calendar.DAY_OF_MONTH) - maxBackupIndex);

break;

case DailyRollingFileAppender.TOP_OF_DAY:
this.set(Calendar.HOUR_OF_DAY, this.get(Calendar.HOUR_OF_DAY));
this.set(Calendar.MINUTE, this.get(Calendar.MINUTE));
this.set(Calendar.SECOND, this.get(Calendar.SECOND));
this.set(Calendar.MILLISECOND, this.get(Calendar.MILLISECOND));
this.set(Calendar.DATE, this.get(Calendar.DATE) - maxBackupIndex);
break;

case DailyRollingFileAppender.TOP_OF_WEEK:
this.set(Calendar.DAY_OF_WEEK, getFirstDayOfWeek());
this.set(Calendar.HOUR_OF_DAY, this.get(Calendar.HOUR_OF_DAY));
this.set(Calendar.MINUTE, this.get(Calendar.MINUTE));
this.set(Calendar.SECOND, this.get(Calendar.SECOND));
this.set(Calendar.MILLISECOND, this.get(Calendar.MILLISECOND));
this.set(Calendar.WEEK_OF_YEAR, this.get(Calendar.WEEK_OF_YEAR) - maxBackupIndex);
break;

case DailyRollingFileAppender.TOP_OF_MONTH:
this.set(Calendar.DATE, this.get(Calendar.DATE));
this.set(Calendar.HOUR_OF_DAY, this.get(Calendar.HOUR_OF_DAY));
this.set(Calendar.MINUTE, this.get(Calendar.MINUTE));
this.set(Calendar.SECOND, this.get(Calendar.SECOND));
this.set(Calendar.MILLISECOND, this.get(Calendar.MILLISECOND));
this.set(Calendar.MONTH, this.get(Calendar.MONTH) - maxBackupIndex);
break;

default:
throw new IllegalStateException("Unknown periodicity type.");
}

return getTime();
}
}

log4j.appender.R=org.apache.log4j.DailyMaxRollingFileAppender
log4j.appender.R.File=${log4j.appender.RLogPath}
log4j.appender.R.DatePattern='.'yyyy-MM-dd
log4j.appender.R.Encoding=UTF-8
log4j.appender.R.Append=true
log4j.appender.R.MaxBackupIndex=7
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%m%n