Package org.apache.commons.logging

Interface Log

All Known Implementing Classes:

NoOpLog, SimpleLog, SLF4JLocationAwareLog, SLF4JLog

public interface Log

A simple logging interface abstracting logging APIs. In order to be instantiated successfully by LogFactory, classes that implement this interface must have a constructor that takes a single String parameter representing the "name" of this Log.

The six logging levels used by Log are (in order):

1. trace (the least serious)
2. debug
3. info
4. warn
5. error
6. fatal (the most serious)

The mapping of these log levels to the concepts used by the underlying logging system is implementation dependent. The implementation should ensure, though, that this ordering behaves as expected.

Performance is often a logging concern. By examining the appropriate property, a component can avoid expensive operations (producing information to be logged).

For example,

    if (log.isDebugEnabled()) {
        ... do something expensive ...
        log.debug(theResult);
    }
 

Configuration of the underlying logging system will generally be done external to the Logging APIs, through whatever mechanism is supported by that system.

Please note that this interface is identical to that found in JCL 1.1.1.

Method Summary

Modifier and Type	Method	Description
void	debug(Object message)	Log a message with debug log level.
void	debug(Object message, Throwable t)	Log an error with debug log level.
void	error(Object message)	Log a message with error log level.
void	error(Object message, Throwable t)	Log an error with error log level.
void	fatal(Object message)	Log a message with fatal log level.
void	fatal(Object message, Throwable t)	Log an error with fatal log level.
void	info(Object message)	Log a message with info log level.
void	info(Object message, Throwable t)	Log an error with info log level.
boolean	isDebugEnabled()	Is debug logging currently enabled?
boolean	isErrorEnabled()	Is error logging currently enabled?
boolean	isFatalEnabled()	Is fatal logging currently enabled?
boolean	isInfoEnabled()	Is info logging currently enabled?
boolean	isTraceEnabled()	Is trace logging currently enabled?
boolean	isWarnEnabled()	Is warn logging currently enabled?
void	trace(Object message)	Log a message with trace log level.
void	trace(Object message, Throwable t)	Log an error with trace log level.
void	warn(Object message)	Log a message with warn log level.
void	warn(Object message, Throwable t)	Log an error with warn log level.

Method Detail

isDebugEnabled

boolean isDebugEnabled()

Is debug logging currently enabled?

Call this method to prevent having to perform expensive operations (for example, String concatenation) when the log level is more than debug.

isErrorEnabled

boolean isErrorEnabled()

Is error logging currently enabled?

Call this method to prevent having to perform expensive operations (for example, String concatenation) when the log level is more than error.

isFatalEnabled

boolean isFatalEnabled()

Is fatal logging currently enabled?

Call this method to prevent having to perform expensive operations (for example, String concatenation) when the log level is more than fatal.

isInfoEnabled

boolean isInfoEnabled()

Is info logging currently enabled?

Call this method to prevent having to perform expensive operations (for example, String concatenation) when the log level is more than info.

Returns:

true if info enabled, false otherwise

isTraceEnabled

boolean isTraceEnabled()

Is trace logging currently enabled?

Call this method to prevent having to perform expensive operations (for example, String concatenation) when the log level is more than trace.

Returns:

true if trace enabled, false otherwise

isWarnEnabled

boolean isWarnEnabled()

Is warn logging currently enabled?

Call this method to prevent having to perform expensive operations (for example, String concatenation) when the log level is more than warn.

trace

void trace(Object message)

Log a message with trace log level.

Parameters:

message - log this message

trace

void trace(Object message,
           Throwable t)

Log an error with trace log level.

Parameters:

message - log this message

t - log this cause

debug

void debug(Object message)

Log a message with debug log level.

Parameters:

message - log this message

debug

void debug(Object message,
           Throwable t)

Log an error with debug log level.

Parameters:

message - log this message

t - log this cause

info

void info(Object message)

Log a message with info log level.

Parameters:

message - log this message

info

void info(Object message,
          Throwable t)

Log an error with info log level.

Parameters:

message - log this message

t - log this cause

warn

void warn(Object message)

Log a message with warn log level.

Parameters:

message - log this message

warn

void warn(Object message,
          Throwable t)

Log an error with warn log level.

Parameters:

message - log this message

t - log this cause

error

void error(Object message)

Log a message with error log level.

Parameters:

message - log this message

error

void error(Object message,
           Throwable t)

Log an error with error log level.

Parameters:

message - log this message

t - log this cause

fatal

void fatal(Object message)

Log a message with fatal log level.

Parameters:

message - log this message

fatal

void fatal(Object message,
           Throwable t)

Log an error with fatal log level.

Parameters:

message - log this message

t - log this cause