public RollingFileAppender() 
{
                      
    super();
}

The default constructor simply calls its parents constructor .

 public RollingFileAppender(Layout layout,
    String filename) throws IOException 
{
    super(layout, filename);
}

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 RollingFileAppender(Layout layout,
    String filename,
    boolean append) throws IOException 
{
    super(layout, filename, append);
}

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 int getMaxBackupIndex() 
{
    return maxBackupIndex;
}

Returns the value of the MaxBackupIndex option.

 public long getMaximumFileSize() 
{
    return maxFileSize;
}

Get the maximum size that the output file is allowed to reach before being rolled over to backup files.

 public  void rollOver() 
{
    File target;
    File file;
    if (qw != null) {
        long size = ((CountingQuietWriter) qw).getCount();
        LogLog.debug("rolling over count=" + size);
        //   if operation fails, do not roll again until
        //      maxFileSize more bytes are written
        nextRollover = size + maxFileSize;
    }
    LogLog.debug("maxBackupIndex="+maxBackupIndex);
    boolean renameSucceeded = true;
    // 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 + '." + maxBackupIndex);
      if (file.exists())
       renameSucceeded = file.delete();
      // Map {(maxBackupIndex - 1), ..., 2, 1} to {maxBackupIndex, ..., 3, 2}
      for (int i = maxBackupIndex - 1; i  >= 1 && renameSucceeded; i--) {
	file = new File(fileName + "." + i);
	if (file.exists()) {
	  target = new File(fileName + '." + (i + 1));
	  LogLog.debug("Renaming file " + file + " to " + target);
	  renameSucceeded = file.renameTo(target);
	}
      }
    if(renameSucceeded) {
      // Rename fileName to fileName.1
      target = new File(fileName + "." + 1);
      this.closeFile(); // keep windows happy.
      file = new File(fileName);
      LogLog.debug("Renaming file " + file + " to " + target);
      renameSucceeded = file.renameTo(target);
      //
      //   if file rename failed, reopen file with append = true
      //
      if (!renameSucceeded) {
          try {
            this.setFile(fileName, true, bufferedIO, bufferSize);
          }
          catch(IOException e) {
            LogLog.error("setFile("+fileName+", true) call failed.", e);
          }
      }
    }
    }
    //
    //   if all renames were successful, then
    //
    if (renameSucceeded) {
    try {
      // This will also close the file. This is OK since multiple
      // close operations are safe.
      this.setFile(fileName, false, bufferedIO, bufferSize);
      nextRollover = 0;
    }
    catch(IOException e) {
      LogLog.error("setFile("+fileName+", false) call failed.", e);
    }
    }
}

Implements the usual roll over behaviour.

If MaxBackupIndex is positive, then files {File.1, ..., File.MaxBackupIndex -1} are renamed to {File.2, ..., File.MaxBackupIndex}. Moreover, File is renamed File.1 and closed. A new File is created to receive further log output.

If MaxBackupIndex is equal to zero, then the File is truncated with no backup files created.

 public synchronized  void setFile(String fileName,
    boolean append,
    boolean bufferedIO,
    int bufferSize) throws IOException 
{
    super.setFile(fileName, append, this.bufferedIO, this.bufferSize);
    if(append) {
      File f = new File(fileName);
      ((CountingQuietWriter) qw).setCount(f.length());
    }
}

 public  void setMaxBackupIndex(int maxBackups) 
{
    this.maxBackupIndex = maxBackups;
}

Set the maximum number of backup files to keep around.

The MaxBackupIndex 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 truncated when it reaches MaxFileSize.

 public  void setMaxFileSize(String value) 
{
    maxFileSize = OptionConverter.toFileSize(value, maxFileSize + 1);
}

Set the maximum size that the output file is allowed to reach before being rolled over to backup files.

In configuration files, the MaxFileSize option takes an long integer in the range 0 - 2^63. You can specify the value with the suffixes "KB", "MB" or "GB" so that the integer is interpreted being expressed respectively in kilobytes, megabytes or gigabytes. For example, the value "10KB" will be interpreted as 10240.

 public  void setMaximumFileSize(long maxFileSize) 
{
    this.maxFileSize = maxFileSize;
}

Set the maximum size that the output file is allowed to reach before being rolled over to backup files.

This method is equivalent to #setMaxFileSize except that it is required for differentiating the setter taking a long argument from the setter taking a String argument by the JavaBeans Introspector .

 protected  void setQWForFiles(Writer writer) 
{
     this.qw = new CountingQuietWriter(writer, errorHandler);
}

 protected  void subAppend(LoggingEvent event) 
{
    super.subAppend(event);
    if(fileName != null && qw != null) {
        long size = ((CountingQuietWriter) qw).getCount();
        if (size  >= maxFileSize && size  >= nextRollover) {
            rollOver();
        }
    }
}

This method differentiates RollingFileAppender from its super class.