org.apache.java.io
Class LogWriter

java.lang.Object
  |
  +--org.apache.java.io.LogWriter

public class LogWriter

extends java.lang.Object

implements Logger

A LogWriter allows an application to incapsulate an output stream and dumps its logs on it.

To control the different kinds of log messages they are separated into channels that can be activated setting to true the right property.

The configurations that control this writer are:

• "identifier" a boolean value that enables the whole logging
• "identifier".dateFormat the date format used to time stamp
• "identifier".timestamp a boolean value that enables time stamping
• "identifier".channel."channelName" a boolean value that enables the specified channel

  Version:

  $Revision: 1.27 $ $Date: 1999/11/09 21:57:40 $

  Inner Class Summary

  protected class

  LogWriter.Agent Class implementing the background logging.

  Field Summary

  boolean	active Tells if this log is active
  static java.lang.String	CH_EXCEPTION_TRACING String identifier for the exception tracing channel.
  static java.lang.String	CH_QUEUE_STATUS
  Configurations	configurations Configuration parameters.
  static java.lang.String	DEFAULT_DATEFORMAT This string control the standard date format used used for log timestamping.
  static java.lang.String	DEFAULT_IDENTIFIER This string identifies this log writer and its used to differentiate between configurations.
  private java.text.SimpleDateFormat	formatter The timestamp formatter.
  private java.lang.String	identifier This string identifies this log writer and its used to discriminate between configuration parameters.
  static java.lang.String	KEYWORD_CHANNEL
  static java.lang.String	KEYWORD_DATEFORMAT
  static java.lang.String	KEYWORD_FILE
  static java.lang.String	KEYWORD_QUEUE_MAXAGE
  static java.lang.String	KEYWORD_QUEUE_MAXSIZE
  static java.lang.String	KEYWORD_TIMESTAMP
  private boolean	logChannel Tells if the log message should contain a channel.
  private LogWriter.Agent	logDaemon Background logger thread.
  protected SimpleQueue	logQueue Log message queue.
  private long	queue_maxage Maximum age of a queued log record, in milliseconds.
  private long	queue_maxsize Maximum size of a log queue.
  private boolean	timestamp Tells if the log message should be started by a time stamp.
  private java.io.PrintWriter	writer The writer encapsulated.

  Constructor Summary

  LogWriter(Configurations configurations)
  Constructs this class and gets output file from configurations.

  LogWriter(java.io.OutputStream output, Configurations configurations)
  Constructs this class with the output stream to encapsulate using default identifier.

  LogWriter(java.io.OutputStream output, java.lang.String identifier, Configurations configurations)
  Constructs this class with the output stream to encapsulate.

  LogWriter(java.lang.String identifier, Configurations configurations)
  Constructs this class using identifier to discriminate between configuration parameters and gets output file from configurations.

  LogWriter(java.io.Writer output, Configurations configurations)
  Constructs this class with the output writer to encapsulate using default identifier.

  LogWriter(java.io.Writer output, java.lang.String identifier, Configurations configurations)
  Constructs this class with the output writer to encapsulate.

  Method Summary

  void	flush() Flush the log.
  boolean	isActive() Tells if it is active.
  boolean	isActive(java.lang.String channel) Tells if the given channel is active.
  void	log(java.lang.String channel, java.lang.String message) Prints the log message on the right channel.
  void	log(java.lang.String channel, java.lang.Throwable t) Prints the error message and stack trace if channel enabled.
  void	log(java.lang.Throwable t) Deprecated.

  Methods inherited from class java.lang.Object

  , clone, equals, finalize, getClass, hashCode, notify, notifyAll, registerNatives, toString, wait, wait, wait

  Field Detail

  DEFAULT_IDENTIFIER

  public static final java.lang.String DEFAULT_IDENTIFIER

  This string identifies this log writer and its used to differentiate between configurations.

  DEFAULT_DATEFORMAT

  public static final java.lang.String DEFAULT_DATEFORMAT

  This string control the standard date format used used for log timestamping.

  KEYWORD_DATEFORMAT

  public static final java.lang.String KEYWORD_DATEFORMAT

  KEYWORD_TIMESTAMP

  public static final java.lang.String KEYWORD_TIMESTAMP

  KEYWORD_CHANNEL

  public static final java.lang.String KEYWORD_CHANNEL

  KEYWORD_FILE

  public static final java.lang.String KEYWORD_FILE

  KEYWORD_QUEUE_MAXAGE

  public static final java.lang.String KEYWORD_QUEUE_MAXAGE

  KEYWORD_QUEUE_MAXSIZE

  public static final java.lang.String KEYWORD_QUEUE_MAXSIZE

  CH_QUEUE_STATUS

  public static final java.lang.String CH_QUEUE_STATUS

  CH_EXCEPTION_TRACING

  public static final java.lang.String CH_EXCEPTION_TRACING

  String identifier for the exception tracing channel.

  configurations

  public Configurations configurations

  Configuration parameters.

  active

  public boolean active

  Tells if this log is active

  queue_maxage

  private long queue_maxage

  Maximum age of a queued log record, in milliseconds.

  When the log daemon detects the record older than this, it flushes the queue, just to make the observer happy, even if that is a single message in the queue.

  Default is hardcoded to 5000 ms.

  queue_maxsize

  private long queue_maxsize

  Maximum size of a log queue.

  When one of the log(...) messages detects that the log queue size is more than this variable permits, it flushes the queue, to keep the memory clean.

  Default is 1000.

  identifier

  private java.lang.String identifier

  This string identifies this log writer and its used to discriminate between configuration parameters.

  timestamp

  private boolean timestamp

  Tells if the log message should be started by a time stamp. Default is false.

  formatter

  private java.text.SimpleDateFormat formatter

  The timestamp formatter.

  writer

  private java.io.PrintWriter writer

  The writer encapsulated.

  logDaemon

  private LogWriter.Agent logDaemon

  Background logger thread.

  logChannel

  private boolean logChannel

  Tells if the log message should contain a channel. Default is false.

  logQueue

  protected SimpleQueue logQueue

  Log message queue. Supposed to keep the messages until they get processed by the background logger thread.

  Constructor Detail

  LogWriter

  public LogWriter(Configurations configurations)
            throws java.io.IOException

  Constructs this class and gets output file from configurations.

  Parameters:

  configurations - the configurations needed at initialization.

  LogWriter

  public LogWriter(java.lang.String identifier,
                   Configurations configurations)
            throws java.io.IOException

  Constructs this class using identifier to discriminate between configuration parameters and gets output file from configurations.

  Parameters:

  identifier - the identifier for this log writer.

  configurations - the configurations needed at initialization.

  LogWriter

  public LogWriter(java.io.Writer output,
                   Configurations configurations)
            throws java.io.IOException

  Constructs this class with the output writer to encapsulate using default identifier.

  Parameters:

  output - the output writer to encapsulate.

  configurations - the configurations needed at initialization.

  LogWriter

  public LogWriter(java.io.OutputStream output,
                   Configurations configurations)
            throws java.io.IOException

  Constructs this class with the output stream to encapsulate using default identifier.

  Parameters:

  output - the output stream to encapsulate.

  configurations - the configurations needed at initialization.

  LogWriter

  public LogWriter(java.io.OutputStream output,
                   java.lang.String identifier,
                   Configurations configurations)
            throws java.io.IOException

  Constructs this class with the output stream to encapsulate. The log identifier is used to discriminate between configuration parameters.

  Parameters:

  output - the output stream to encapsulate.

  identifier - the identifier for this log writer.

  configurations - the configurations needed at initialization.

  LogWriter

  public LogWriter(java.io.Writer output,
                   java.lang.String identifier,
                   Configurations configurations)
            throws java.io.IOException

  Constructs this class with the output writer to encapsulate. The log identifier is used to discriminate between configuration parameters.

  Parameters:

  output - the output writer to encapsulate.

  identifier - the identifier for this log writer.

  configurations - the configurations needed at initialization.

  Method Detail

  isActive

  public boolean isActive()

  Tells if it is active.

  Specified by:

  isActive in interface Logger

  isActive

  public boolean isActive(java.lang.String channel)

  Tells if the given channel is active.

  Specified by:

  isActive in interface Logger

  Parameters:

  channel - the channel to test.

  log

  public void log(java.lang.String channel,
                  java.lang.String message)

  Prints the log message on the right channel.

  A "channel" is a virtual log that may be enabled or disabled by setting the property "identifier".channel.???=true where ??? is the channel identifier that must be passed with the message. If a channel is not recognized or its property is set to false the message is not written.

  Specified by:

  log in interface Logger

  Parameters:

  channel - the channel to put the message on.

  name - the message to log.

  log

  public void log(java.lang.String channel,
                  java.lang.Throwable t)

  Prints the error message and stack trace if channel enabled.

  Specified by:

  log in interface Logger

  Parameters:

  t - the error thrown.

  log

  public void log(java.lang.Throwable t)

  Deprecated.

  flush

  public void flush()

  Flush the log. Write any pending messages into the log media.

  Specified by:

  flush in interface Logger