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What this is

This file is included in the "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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The source code

 * Copyright (C) The Apache Software Foundation. All rights reserved.
 * This software is published under the terms of the Apache Software
 * License version 1.1, a copy of which has been included with this
 * distribution in the LICENSE.APL file.  */

package org.apache.log4j;

import java.text.SimpleDateFormat;
import java.util.Date;
import org.apache.log4j.helpers.OptionConverter;
import org.apache.log4j.helpers.QuietWriter;
import org.apache.log4j.helpers.CountingQuietWriter;
import org.apache.log4j.spi.LoggingEvent;
import org.apache.log4j.spi.ErrorCode;

   DailyFileAppender extends FileAppender to use filenames formatted with
   date/time information. The filename is recomputed every day at midnight.
   Note that the filename doesn't have to change every day, making it possible
   to have logfiles which are per-week or per-month.

   The appender computes the proper filename using the formats specified in
   java.text.SimpleDateFormat. The format requires that most static text is
   enclosed in single quotes, which are removed. The examples below show how
   quotes are used to embed static information in the format.

   Sample filenames:

     Filename pattern                     Filename
     "'/logs/trace-'yyyy-MM-dd'.log'"     /logs/trace-2000-12-31.log
     "'/logs/trace-'yyyy-ww'.log'"        /logs/trace-2000-52.log

   @author Eirik Lygre
public class DailyFileAppender extends FileAppender {

     A string constant used in naming the option for setting the
     filename pattern. Current value of this string constant is
  static final public String FILE_NAME_PATTERN_OPTION = "FilePattern";
     The filename pattern
  private String fileNamePattern = null;

     The actual formatted filename that is currently being written to
  private String currentFileName = null;

     The timestamp when we shall next recompute the filename
  private long nextFilenameComputingMillis = System.currentTimeMillis () - 1;

     The default constructor does no longer set a default layout nor a
     default output target.  */
  DailyFileAppender() {

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


If the append parameter is true, the file will be appended to. Otherwise, the file desginated by filename will be truncated before being opened. */ public DailyFileAppender (Layout layout,String filename,boolean append) throws IOException { super(layout, filename, append); } /** Instantiate a FileAppender and open the file designated by filename. The opened filename will become the output destination for this appender.

The file will be appended to. */ public DailyFileAppender (Layout layout,String filename) throws IOException { super(layout, filename); } /** Set the current output file. The function will compute a new filename, and open a new file only when the name has changed. The function is automatically called once a day, to allow for daily files -- the purpose of this class. */ public synchronized void setFile(String fileName, boolean append) throws IOException { /* Compute filename, but only if fileNamePattern is specified */ if (fileNamePattern == null) { errorHandler.error("Missing file pattern (" + FILE_NAME_PATTERN_OPTION + ") in setFile()."); return; } Date now = new Date(); fileName = new SimpleDateFormat(fileNamePattern).format (now); if (fileName.equals(currentFileName)) return; /* Set up next filename checkpoint */ DailyFileAppenderCalendar c = new DailyFileAppenderCalendar(); c.rollToNextDay (); nextFilenameComputingMillis = c.getTimeInMillis (); currentFileName = fileName; super.setFile(fileName, append); } /** This method differentiates RollingFileAppender from its super class. */ protected void subAppend(LoggingEvent event) { if (System.currentTimeMillis () >= nextFilenameComputingMillis) { try { setFile (super.fileName, super.fileAppend); } catch(IOException e) { System.err.println("setFile(null, false) call failed."); e.printStackTrace(); } } super.subAppend(event); } /** Retuns the option names for this component, namely {@link #FILE_NAME_PATTERN_OPTION} in addition to the options of {@link FileAppender#getOptionStrings FileAppender}. */ public String[] getOptionStrings() { return OptionConverter.concatanateArrays(super.getOptionStrings(), new String[] {FILE_NAME_PATTERN_OPTION}); } /** Set the options for the appender */ public void setOption(String key, String value) { super.setOption(key, value); if(key.equalsIgnoreCase(FILE_NAME_PATTERN_OPTION)) { fileNamePattern = value; } } /** If the a value for {@link #FILE_OPTION} is non-null, then {@link #setFile} is called with the values of {@link #FILE_OPTION} and {@link #APPEND_OPTION}. @since 0.8.1 */ public void activateOptions() { try { setFile(null, super.fileAppend); } catch( e) { errorHandler.error("setFile(null,"+fileAppend+") call failed.", e, ErrorCode.FILE_OPEN_FAILURE); } } } /** DailyFileAppenderCalendar is a helper class to DailyFileAppender. Using this class, it is easy to compute and access the next Millis() It subclasses the standard java.util.GregorianCalendar-object, to allow access to the protected function getTimeInMillis(), which it then exports. @author Eirik Lygre */ class DailyFileAppenderCalendar extends java.util.GregorianCalendar { /** Returns the current time in Millis */ public long getTimeInMillis() { return super.getTimeInMillis(); } /** Roll the date to the next hour, with minute, second and millisecond set to zero. */ public void rollToNextDay () { this.add(java.util.Calendar.DATE, 0); this.add(java.util.Calendar.HOUR, 0); this.set(java.util.Calendar.MINUTE, 0); this.set(java.util.Calendar.SECOND, 0); this.set(java.util.Calendar.MILLISECOND, 0); } }

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