Package org.slf4j.impl

Class SimpleLogger

java.lang.Object
org.slf4j.helpers.NamedLoggerBase
org.slf4j.helpers.MarkerIgnoringBase
org.slf4j.impl.SimpleLogger
All Implemented Interfaces:
Serializable, Logger
public class SimpleLogger extends MarkerIgnoringBase

Simple implementation of Logger that sends all enabled log messages, for all defined loggers, to the console (System.err). The following system properties are supported to configure the behavior of this logger:

  • org.slf4j.simpleLogger.logFile - The output target which can be the path to a file, or the special values "System.out" and "System.err". Default is "System.err".
  • org.slf4j.simpleLogger.cacheOutputStream - If the output target is set to "System.out" or "System.err" (see preceding entry), by default, logs will be output to the latest value referenced by System.out/err variables. By setting this parameter to true, the output stream will be cached, i.e. assigned once at initialization time and re-used independently of the current value referenced by System.out/err.
  • org.slf4j.simpleLogger.defaultLogLevel - Default log level for all instances of SimpleLogger. Must be one of ("trace", "debug", "info", "warn", "error" or "off"). If not specified, defaults to "info".
  • org.slf4j.simpleLogger.log.a.b.c - Logging detail level for a SimpleLogger instance named "a.b.c". Right-side value must be one of "trace", "debug", "info", "warn", "error" or "off". When a SimpleLogger named "a.b.c" is initialized, its level is assigned from this property. If unspecified, the level of nearest parent logger will be used, and if none is set, then the value specified by org.slf4j.simpleLogger.defaultLogLevel will be used.
  • org.slf4j.simpleLogger.showDateTime - Set to true if you want the current date and time to be included in output messages. Default is false
  • org.slf4j.simpleLogger.dateTimeFormat - The date and time format to be used in the output messages. The pattern describing the date and time format is defined by SimpleDateFormat. If the format is not specified or is invalid, the number of milliseconds since start up will be output.
  • org.slf4j.simpleLogger.showThreadName -Set to true if you want to output the current thread name. Defaults to true.
  • org.slf4j.simpleLogger.showLogName - Set to true if you want the Logger instance name to be included in output messages. Defaults to true.
  • org.slf4j.simpleLogger.showShortLogName - Set to true if you want the last component of the name to be included in output messages. Defaults to false.
  • org.slf4j.simpleLogger.levelInBrackets - Should the level string be output in brackets? Defaults to false.
  • org.slf4j.simpleLogger.warnLevelString - The string value output for the warn level. Defaults to WARN.

In addition to looking for system properties with the names specified above, this implementation also checks for a class loader resource named "simplelogger.properties", and includes any matching definitions from this resource (if it exists).

With no configuration, the default output includes the relative time in milliseconds, thread name, the level, logger name, and the message followed by the line separator for the host. In log4j terms it amounts to the "%r [%t] %level %logger - %m%n" pattern.

Sample output follows. 

 176 [main] INFO examples.Sort - Populating an array of 2 elements in reverse order.
 225 [main] INFO examples.SortAlgo - Entered the sort method.
 304 [main] INFO examples.SortAlgo - Dump of integer array:
 317 [main] INFO examples.SortAlgo - Element [0] = 0
 331 [main] INFO examples.SortAlgo - Element [1] = 1
 343 [main] INFO examples.Sort - The next log statement should be an error message.
 346 [main] ERROR examples.SortAlgo - Tried to dump an uninitialized array.
   at org.log4j.examples.SortAlgo.dump(SortAlgo.java:58)
   at org.log4j.examples.Sort.main(Sort.java:64)
 467 [main] INFO  examples.Sort - Exiting main method.

This implementation is heavily inspired by Apache Commons Logging's SimpleLog.

See Also:

  • Field Details

  • Constructor Details

    • SimpleLogger

      SimpleLogger(String name)
      Package access allows only SimpleLoggerFactory to instantiate SimpleLogger instances.

  • Method Details

    • lazyInit

      static void lazyInit()

    • init

      static void init()

    • recursivelyComputeLevelString

      String recursivelyComputeLevelString()

    • log

      private void log(int level, String message, Throwable t)
      This is our internal implementation for logging regular (non-parameterized) log messages.
      Parameters:
      level - One of the LOG_LEVEL_XXX constants defining the log level
      message - The message itself
      t - The exception whose stack trace should be logged

    • renderLevel

      protected String renderLevel(int level)

    • write

      void write(StringBuilder buf, Throwable t)
      To avoid intermingling of log messages and associated stack traces, the two operations are done in a synchronized block.
      Parameters:
      buf -
      t -

    • writeThrowable

      protected void writeThrowable(Throwable t, PrintStream targetStream)

    • getFormattedDate

      private String getFormattedDate()

    • computeShortName

      private String computeShortName()

    • formatAndLog

      private void formatAndLog(int level, String format, Object arg1, Object arg2)
      For formatted messages, first substitute arguments and then log.
      Parameters:
      level -
      format -
      arg1 -
      arg2 -

    • formatAndLog

      private void formatAndLog(int level, String format, Object... arguments)
      For formatted messages, first substitute arguments and then log.
      Parameters:
      level -
      format -
      arguments - a list of 3 ore more arguments

    • isLevelEnabled

      protected boolean isLevelEnabled(int logLevel)
      Is the given log level currently enabled?
      Parameters:
      logLevel - is this level enabled?

    • isTraceEnabled

      public boolean isTraceEnabled()
      Are trace messages currently enabled?
      Returns:
      True if this Logger is enabled for the TRACE level, false otherwise.

    • trace

      public void trace(String msg)
      A simple implementation which logs messages of level TRACE according to the format outlined above.
      Parameters:
      msg - the message string to be logged

    • trace

      public void trace(String format, Object param1)
      Perform single parameter substitution before logging the message of level TRACE according to the format outlined above.
      Parameters:
      format - the format string
      param1 - the argument

    • trace

      public void trace(String format, Object param1, Object param2)
      Perform double parameter substitution before logging the message of level TRACE according to the format outlined above.
      Parameters:
      format - the format string
      param1 - the first argument
      param2 - the second argument

    • trace

      public void trace(String format, Object... argArray)
      Perform double parameter substitution before logging the message of level TRACE according to the format outlined above.
      Parameters:
      format - the format string
      argArray - a list of 3 or more arguments

    • trace

      public void trace(String msg, Throwable t)
      Log a message of level TRACE, including an exception.
      Parameters:
      msg - the message accompanying the exception
      t - the exception (throwable) to log

    • isDebugEnabled

      public boolean isDebugEnabled()
      Are debug messages currently enabled?
      Returns:
      True if this Logger is enabled for the DEBUG level, false otherwise.

    • debug

      public void debug(String msg)
      A simple implementation which logs messages of level DEBUG according to the format outlined above.
      Parameters:
      msg - the message string to be logged

    • debug

      public void debug(String format, Object param1)
      Perform single parameter substitution before logging the message of level DEBUG according to the format outlined above.
      Parameters:
      format - the format string
      param1 - the argument

    • debug

      public void debug(String format, Object param1, Object param2)
      Perform double parameter substitution before logging the message of level DEBUG according to the format outlined above.
      Parameters:
      format - the format string
      param1 - the first argument
      param2 - the second argument

    • debug

      public void debug(String format, Object... argArray)
      Perform double parameter substitution before logging the message of level DEBUG according to the format outlined above.
      Parameters:
      format - the format string
      argArray - a list of 3 or more arguments

    • debug

      public void debug(String msg, Throwable t)
      Log a message of level DEBUG, including an exception.
      Parameters:
      msg - the message accompanying the exception
      t - the exception (throwable) to log

    • isInfoEnabled

      public boolean isInfoEnabled()
      Are info messages currently enabled?
      Returns:
      True if this Logger is enabled for the INFO level, false otherwise.

    • info

      public void info(String msg)
      A simple implementation which logs messages of level INFO according to the format outlined above.
      Parameters:
      msg - the message string to be logged

    • info

      public void info(String format, Object arg)
      Perform single parameter substitution before logging the message of level INFO according to the format outlined above.
      Parameters:
      format - the format string
      arg - the argument

    • info

      public void info(String format, Object arg1, Object arg2)
      Perform double parameter substitution before logging the message of level INFO according to the format outlined above.
      Parameters:
      format - the format string
      arg1 - the first argument
      arg2 - the second argument

    • info

      public void info(String format, Object... argArray)
      Perform double parameter substitution before logging the message of level INFO according to the format outlined above.
      Parameters:
      format - the format string
      argArray - a list of 3 or more arguments

    • info

      public void info(String msg, Throwable t)
      Log a message of level INFO, including an exception.
      Parameters:
      msg - the message accompanying the exception
      t - the exception (throwable) to log

    • isWarnEnabled

      public boolean isWarnEnabled()
      Are warn messages currently enabled?
      Returns:
      True if this Logger is enabled for the WARN level, false otherwise.

    • warn

      public void warn(String msg)
      A simple implementation which always logs messages of level WARN according to the format outlined above.
      Parameters:
      msg - the message string to be logged

    • warn

      public void warn(String format, Object arg)
      Perform single parameter substitution before logging the message of level WARN according to the format outlined above.
      Parameters:
      format - the format string
      arg - the argument

    • warn

      public void warn(String format, Object arg1, Object arg2)
      Perform double parameter substitution before logging the message of level WARN according to the format outlined above.
      Parameters:
      format - the format string
      arg1 - the first argument
      arg2 - the second argument

    • warn

      public void warn(String format, Object... argArray)
      Perform double parameter substitution before logging the message of level WARN according to the format outlined above.
      Parameters:
      format - the format string
      argArray - a list of 3 or more arguments

    • warn

      public void warn(String msg, Throwable t)
      Log a message of level WARN, including an exception.
      Parameters:
      msg - the message accompanying the exception
      t - the exception (throwable) to log

    • isErrorEnabled

      public boolean isErrorEnabled()
      Are error messages currently enabled?
      Returns:
      True if this Logger is enabled for the ERROR level, false otherwise.

    • error

      public void error(String msg)
      A simple implementation which always logs messages of level ERROR according to the format outlined above.
      Parameters:
      msg - the message string to be logged

    • error

      public void error(String format, Object arg)
      Perform single parameter substitution before logging the message of level ERROR according to the format outlined above.
      Parameters:
      format - the format string
      arg - the argument

    • error

      public void error(String format, Object arg1, Object arg2)
      Perform double parameter substitution before logging the message of level ERROR according to the format outlined above.
      Parameters:
      format - the format string
      arg1 - the first argument
      arg2 - the second argument

    • error

      public void error(String format, Object... argArray)
      Perform double parameter substitution before logging the message of level ERROR according to the format outlined above.
      Parameters:
      format - the format string
      argArray - a list of 3 or more arguments

    • error

      public void error(String msg, Throwable t)
      Log a message of level ERROR, including an exception.
      Parameters:
      msg - the message accompanying the exception
      t - the exception (throwable) to log

    • log

      public void log(LoggingEvent event)