## org.apache.log4j
Class DailyRollingFileAppender

    java.lang.Object
      org.apache.log4j.AppenderSkeleton
          org.apache.log4j.WriterAppender
              org.apache.log4j.FileAppender
                  org.apache.log4j.DailyRollingFileAppender

All Implemented Interfaces:
  Appender, OptionHandler

    public class DailyRollingFileAppender

extends FileAppender

DailyRollingFileAppender extends `FileAppender` so that the underlying file is rolled over at a user chosen frequency. 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.

The rolling schedule is specified by the DatePattern option. This pattern should follow the `SimpleDateFormat` conventions. In particular, you must 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.

For example, if the File option is set to `/foo/bar.log` and the DatePattern set to `'.'yyyy-MM-dd`, on 2001-02-16 at midnight, the logging file `/foo/bar.log` will be copied to `/foo/bar.log.2001-02-16` and logging for 2001-02-17 will continue in `/foo/bar.log` until it rolls over the next day.

Is is possible to specify monthly, weekly, half-daily, daily, hourly, or minutely rollover schedules.

DatePattern | Rollover schedule | Example
--- | --- | ---
`'.'yyyy-MM` | Rollover at the beginning of each month | At midnight of May 31st, 2002 `/foo/bar.log` will be copied to `/foo/bar.log.2002-05`. Logging for the month of June will be output to `/foo/bar.log` until it is also rolled over the next month.
`'.'yyyy-ww` | Rollover at the first day of each week. The first day of the week depends on the locale. | Assuming the first day of the week is Sunday, on Saturday midnight, June 9th 2002, the file /foo/bar.log will be copied to /foo/bar.log.2002-23. Logging for the 24th week of 2002 will be output to `/foo/bar.log` until it is rolled over the next week.
`'.'yyyy-MM-dd` | Rollover at midnight each day. | At midnight, on March 8th, 2002, `/foo/bar.log` will be copied to `/foo/bar.log.2002-03-08`. Logging for the 9th day of March will be output to `/foo/bar.log` until it is rolled over the next day.
`'.'yyyy-MM-dd-a` | Rollover at midnight and midday of each day. | At noon, on March 9th, 2002, `/foo/bar.log` will be copied to `/foo/bar.log.2002-03-09-AM`. Logging for the afternoon of the 9th will be output to `/foo/bar.log` until it is rolled over at midnight.
`'.'yyyy-MM-dd-HH` | Rollover at the top of every hour. | At approximately 11:00.000 o'clock on March 9th, 2002, `/foo/bar.log` will be copied to `/foo/bar.log.2002-03-09-10`. Logging for the 11th hour of the 9th of March will be output to `/foo/bar.log` until it is rolled over at the beginning of the next hour.
`'.'yyyy-MM-dd-HH-mm` | Rollover at the beginning of every minute. | At approximately 11:23,000, on March 9th, 2001, `/foo/bar.log` will be copied to `/foo/bar.log.2001-03-09-10-22`. Logging for the minute of 11:23 (9th of March) will be output to `/foo/bar.log` until it is rolled over the next minute.

Do not use the colon ":" character in anywhere in the DatePattern 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, Ceki Gülcü

Field Summary

Fields inherited from class org.apache.log4j.FileAppender
`bufferedIO, bufferSize, fileAppend, fileName`

Fields inherited from class org.apache.log4j.WriterAppender
`encoding, immediateFlush, qw`

Fields inherited from class org.apache.log4j.AppenderSkeleton
`closed, errorHandler, headFilter, layout, name, tailFilter, threshold`

Constructor Summary
`DailyRollingFileAppender()` The default constructor does nothing.
`DailyRollingFileAppender(Layout layout, String filename, String datePattern)` Instantiate a `DailyRollingFileAppender` and open the file designated by `filename`.

Method Summary
`void` `activateOptions()` If the value of File is not `null`, then `FileAppender.setFile(java.lang.String)` is called with the values of File and Append properties.
`String` `getDatePattern()` Returns the value of the DatePattern option.
`void` `setDatePattern(String pattern)` The DatePattern takes a string in the same format as expected by `SimpleDateFormat`.
`protected void` `subAppend(LoggingEvent event)` This method differentiates DailyRollingFileAppender from its super class.

Methods inherited from class org.apache.log4j.FileAppender
`closeFile, getAppend, getBufferedIO, getBufferSize, getFile, reset, setAppend, setBufferedIO, setBufferSize, setFile, setFile, setQWForFiles`

Methods inherited from class org.apache.log4j.WriterAppender
`append, checkEntryConditions, close, closeWriter, createWriter, getEncoding, getImmediateFlush, requiresLayout, setEncoding, setErrorHandler, setImmediateFlush, setWriter, shouldFlush, writeFooter, writeHeader`

Methods inherited from class org.apache.log4j.AppenderSkeleton
`addFilter, clearFilters, doAppend, finalize, getErrorHandler, getFilter, getFirstFilter, getLayout, getName, getThreshold, isAsSevereAsThreshold, setLayout, setName, setThreshold`

Methods inherited from class java.lang.Object
`clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### DailyRollingFileAppender

    public DailyRollingFileAppender()

  The default constructor does nothing.

### DailyRollingFileAppender

    public DailyRollingFileAppender(Layout layout,
                                    String filename,
                                    String datePattern)
                             throws IOException

  Instantiate a `DailyRollingFileAppender` and open the file designated by `filename`. The opened filename will become the ouput destination for this appender.

  Throws:
    `IOException`

Method Detail

### setDatePattern

    public void setDatePattern(String pattern)

  The DatePattern takes a string in the same format as expected by `SimpleDateFormat`. This options determines the rollover schedule.

### getDatePattern

    public String getDatePattern()

  Returns the value of the DatePattern option.

### activateOptions

    public void activateOptions()

  Description copied from class: `FileAppender`
  If the value of File is not `null`, then `FileAppender.setFile(java.lang.String)` is called with the values of File and Append properties.

  Specified by:
    `activateOptions` in interface `OptionHandler`
  Overrides:
    `activateOptions` in class `FileAppender`

### subAppend

    protected void subAppend(LoggingEvent event)

  This method differentiates DailyRollingFileAppender from its super class.

  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.

  Overrides:
    `subAppend` in class `WriterAppender`

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