org.apache.poi.util

Interface POILogger

All Known Implementing Classes:

CommonsLogger, NullLogger, SLF4JLogger, SystemOutLogger

@Internal
public interface POILogger

A logger interface that strives to make it as easy as possible for developers to write log calls, while simultaneously making those calls as cheap as possible by performing lazy evaluation of the log message. A logger can be selected via system properties, e.g. -Dorg.apache.poi.util.POILogger=org.apache.poi.util.SystemOutLogger The following Logger-implementations are provided:

• NullLogger
• CommonsLogger
• SystemOutLogger

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEBUG
static int	ERROR
static int	FATAL
static int	INFO
static int	WARN

Method Summary

Modifier and Type	Method and Description
void	_log(int level, java.lang.Object obj1) Log a message - belongs to the SPI, usually not called from user code
void	_log(int level, java.lang.Object obj1, java.lang.Throwable exception) Log a message - belongs to the SPI, usually not called from user code
boolean	check(int level) Check if a logger is enabled to log at the specified level This allows code to avoid building strings or evaluating functions in the arguments to log.
void	initialize(java.lang.String cat) Initialize the Logger - belongs to the SPI, called from the POILogFactory
default void	log(int level, java.lang.Object... objs) Log a message.

Field Detail

DEBUG

static final int DEBUG

See Also:

Constant Field Values

INFO

static final int INFO

See Also:

Constant Field Values

WARN

static final int WARN

See Also:

Constant Field Values

ERROR

static final int ERROR

See Also:

Constant Field Values

FATAL

static final int FATAL

See Also:

Constant Field Values

Method Detail

initialize

void initialize(java.lang.String cat)

Initialize the Logger - belongs to the SPI, called from the POILogFactory

Parameters:

cat - the String that defines the log

_log

@Internal
void _log(int level,
                    java.lang.Object obj1)

Log a message - belongs to the SPI, usually not called from user code

Parameters:

level - One of DEBUG, INFO, WARN, ERROR, FATAL

obj1 - The object to log. This is converted to a string.

_log

@Internal
void _log(int level,
                    java.lang.Object obj1,
                    java.lang.Throwable exception)

Log a message - belongs to the SPI, usually not called from user code

Parameters:

level - One of DEBUG, INFO, WARN, ERROR, FATAL

obj1 - The object to log. This is converted to a string.

exception - An exception to be logged

check

boolean check(int level)

Check if a logger is enabled to log at the specified level This allows code to avoid building strings or evaluating functions in the arguments to log. An example:

 if (logger.check(POILogger.INFO)) {
     logger.log(POILogger.INFO, "Avoid concatenating ", " strings and evaluating ", functions());
 }
 

Parameters:

level - One of DEBUG, INFO, WARN, ERROR, FATAL

log

default void log(int level,
                 java.lang.Object... objs)

Log a message. Lazily appends Object parameters together. If the last parameter is a Throwable it is logged specially.

Parameters:

level - One of DEBUG, INFO, WARN, ERROR, FATAL

objs - the objects to place in the message