Package eu.woolplatform.utils.log

Class AbstractLogDelegate

java.lang.Object

eu.woolplatform.utils.log.AbstractLogDelegate

All Implemented Interfaces:

LogDelegate

Direct Known Subclasses:

DefaultLogDelegate

public abstract class AbstractLogDelegate
extends Object
implements LogDelegate

This abstract log delegate provides the following features:

• Every line that is printed in a log message will get three tags: the log level, the message tag (identifies the source of the log message) and the current date and time.
• Capture standard output and standard error. Everything that is printed to standard output and standard error can get the same treatment as other log messages. Lines on standard output will be logged at level INFO with tag "STDOUT". Lines on standard error will be logged at level ERROR with tag "STDERR". This feature is by default disabled, but it can be enabled with setCaptureStdOut() and setCaptureStdErr().
• Log files. All log messages can be written to log files using a FileLogger. This feature can be enabled with setFileLogger().

The first time an instance of this class is constructed, it will store the current values of System.out and System.err. You should ensure that they have the default system values. The values are changed when you call setCaptureStdOut(true) or setCaptureStdErr(true). The default system values are restored when you call setCaptureStdOut(false) and setCaptureStdErr(false).

Subclasses can get access to the default system values with the methods getDefaultStdOut() and getDefaultStdErr(). If a log message needs to be printed to standard output or standard error, these default system values MUST be used. Otherwise the log messages will be recursively captured.

A subclass need only implement printTaggedMessage().

Every log method may return an error code. This is in fact an OR of error constants defined in this class or a subclass. This class defines the following constants:

• ERROR_WRITE_FILE

Field Summary

Fields

Modifier and Type	Field	Description
protected static int	ERROR_BASE	Subclasses can define error codes starting at this constant.
static int	ERROR_WRITE_FILE	This error code indicates that an error occurred while writing a log message to a log file.

Constructor Summary

Constructors

Constructor	Description
AbstractLogDelegate()	Constructs a new abstract log delegate.

Method Summary

Modifier and Type	Method	Description
int	d(String tag, String msg)	Writes a message at level DEBUG.
int	d(String tag, String msg, Throwable tr)	Writes a message at level DEBUG.
int	e(String tag, String msg)	Writes a message at level ERROR.
int	e(String tag, String msg, Throwable tr)	Writes a message at level ERROR.
protected PrintStream	getDefaultStdErr()	Returns the default system value of System.err.
protected PrintStream	getDefaultStdOut()	Returns the default system value of System.out.
FileLogger	getFileLogger()	Returns the file logger.
String	getStackTraceString(Throwable tr)	Returns the stack trace string for the specified exception.
int	i(String tag, String msg)	Writes a message at level INFO.
int	i(String tag, String msg, Throwable tr)	Writes a message at level INFO.
boolean	isLoggable(String tag, int level)	Determines if messages at the specified level are logged for the specified tag.
int	println(int priority, String tag, String msg)	Writes a log message.
abstract int	printTaggedMessage(int priority, String tag, String msg)	Writes a log message.
void	setCaptureStdErr(boolean capture)	Sets whether standard error should be captured.
void	setCaptureStdOut(boolean capture)	Sets whether standard output should be captured.
void	setFileLogger(FileLogger fileLogger)	Sets a file logger to which log messages should be written.
void	setLogLevel(int level)	Sets the default log level.
void	setLogLevel(String tag, int level)	Sets the log level for messages with the specified tag.
void	setLogLevels(File xmlFile)	Sets the log levels as defined in an XML file.
void	setLogLevels(InputStream in)	Sets the log levels as defined in an XML file.
int	v(String tag, String msg)	Writes a message at level VERBOSE.
int	v(String tag, String msg, Throwable tr)	Writes a message at level VERBOSE.
int	w(String tag, String msg)	Writes a message at level WARN.
int	w(String tag, String msg, Throwable tr)	Writes a message at level WARN.
int	w(String tag, Throwable tr)	Writes a message at level WARN.
int	wtf(String tag, String msg)	Writes a message at level ASSERT.
int	wtf(String tag, String msg, Throwable tr)	Writes a message at level ASSERT.
int	wtf(String tag, Throwable tr)	Writes a message at level ASSERT.

Methods inherited from class java.lang.Object

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

Field Detail

ERROR_WRITE_FILE

public static int ERROR_WRITE_FILE

This error code indicates that an error occurred while writing a log message to a log file.

ERROR_BASE

protected static int ERROR_BASE

Subclasses can define error codes starting at this constant. An error code should have exactly one bit set, in order that an OR of error codes is possible.

Constructor Detail

AbstractLogDelegate

public AbstractLogDelegate()

Constructs a new abstract log delegate. The first time an abstract log delegate is constructed, you should ensure that System.out and System.err have the default system values.

Method Detail

setLogLevels

public void setLogLevels(File xmlFile)
                  throws ParseException,
                         IOException

Sets the log levels as defined in an XML file.

Parameters:

xmlFile - the XML file

Throws:

ParseException - if the content of the XML file is invalid

IOException - if a reading error occurs

setLogLevels

public void setLogLevels(InputStream in)
                  throws ParseException,
                         IOException

Sets the log levels as defined in an XML file.

Parameters:

in - the input stream for the XML file

Throws:

ParseException - if the content of the XML file is invalid

IOException - if a reading error occurs

setLogLevel

public void setLogLevel(int level)

Sets the default log level. This level is used for message tags for which no specific log level was set (e.g. with setLogLevel(tag, level)). The logger will not write log messages at a lower level than the specified level.

Parameters:

level - the log level

setLogLevel

public void setLogLevel(String tag,
                        int level)

Sets the log level for messages with the specified tag. The logger will not write log messages at a lower level than the specified level.

Parameters:

tag - the message tag

level - the log level

setCaptureStdOut

public void setCaptureStdOut(boolean capture)

Sets whether standard output should be captured.

Parameters:

capture - true if standard output should be captured, false otherwise

setCaptureStdErr

public void setCaptureStdErr(boolean capture)

Sets whether standard error should be captured.

Parameters:

capture - true if standard error should be captured, false otherwise

setFileLogger

public void setFileLogger(FileLogger fileLogger)

Sets a file logger to which log messages should be written. You may set this to null to disable logging to files (that is the default).

Parameters:

fileLogger - the file logger or null

getFileLogger

public FileLogger getFileLogger()

Returns the file logger. If not file logger was set, this method returns null.

Returns:

the file logger or null

getDefaultStdOut

protected PrintStream getDefaultStdOut()

Returns the default system value of System.out. Subclasses must use this value if they want to print to standard output, because the current value of System.out may be a stream that is captured by the logger.

Returns:

the default standard output

getDefaultStdErr

protected PrintStream getDefaultStdErr()

Returns the default system value of System.err. Subclasses must use this value if they want to print to standard error, because the current value of System.err may be a stream that is captured by the logger.

Returns:

the default standard error

println

public int println(int priority,
                   String tag,
                   String msg)

Description copied from interface: LogDelegate

Writes a log message.

Specified by:

println in interface LogDelegate

Parameters:

priority - the log level

tag - the tag

msg - the message

Returns:

0 if no error occurred, an error code otherwise

printTaggedMessage

public abstract int printTaggedMessage(int priority,
                                       String tag,
                                       String msg)

Writes a log message. Every line in the message text has already been tagged with the log level, message tag (identifier of the source of the log message) and the current date and time. Every line ends with a new line character, including the last line.

This method is only called if isLoggable() returns true. It's called inside a lock, so it's thread safe.

For returned error codes, a subclass may define its own error codes based on ERROR_BASE.

Parameters:

priority - the log level

tag - the message tag

msg - the tagged message

Returns:

0 if no error occurred, an error code otherwise.

getStackTraceString

public String getStackTraceString(Throwable tr)

Description copied from interface: LogDelegate

Returns the stack trace string for the specified exception. The returned string probably contains new lines, but it does not have a trailing new line.

Specified by:

getStackTraceString in interface LogDelegate

Parameters:

tr - the exception

Returns:

the stack trace string

isLoggable

public boolean isLoggable(String tag,
                          int level)

Description copied from interface: LogDelegate

Determines if messages at the specified level are logged for the specified tag.

Specified by:

isLoggable in interface LogDelegate

Parameters:

tag - the tag

level - the level

Returns:

true if the message will be logged, false otherwise

d

public int d(String tag,
             String msg,
             Throwable tr)

Description copied from interface: LogDelegate

Writes a message at level DEBUG.

Specified by:

d in interface LogDelegate

Parameters:

tag - the tag

msg - the message

tr - an exception

Returns:

0 if no error occurred, an error code otherwise

d

public int d(String tag,
             String msg)

Description copied from interface: LogDelegate

Writes a message at level DEBUG.

Specified by:

d in interface LogDelegate

Parameters:

tag - the tag

msg - the message

Returns:

0 if no error occurred, an error code otherwise

e

public int e(String tag,
             String msg)

Description copied from interface: LogDelegate

Writes a message at level ERROR.

Specified by:

e in interface LogDelegate

Parameters:

tag - the tag

msg - the message

Returns:

0 if no error occurred, an error code otherwise

e

public int e(String tag,
             String msg,
             Throwable tr)

Description copied from interface: LogDelegate

Writes a message at level ERROR.

Specified by:

e in interface LogDelegate

Parameters:

tag - the tag

msg - the message

tr - an exception

Returns:

0 if no error occurred, an error code otherwise

i

public int i(String tag,
             String msg,
             Throwable tr)

Description copied from interface: LogDelegate

Writes a message at level INFO.

Specified by:

i in interface LogDelegate

Parameters:

tag - the tag

msg - the message

tr - an exception

Returns:

0 if no error occurred, an error code otherwise

i

public int i(String tag,
             String msg)

Description copied from interface: LogDelegate

Writes a message at level INFO.

Specified by:

i in interface LogDelegate

Parameters:

tag - the tag

msg - the message

Returns:

0 if no error occurred, an error code otherwise

v

public int v(String tag,
             String msg,
             Throwable tr)

Description copied from interface: LogDelegate

Writes a message at level VERBOSE.

Specified by:

v in interface LogDelegate

Parameters:

tag - the tag

msg - the message

tr - an exception or null

Returns:

0 if no error occurred, an error code otherwise

v

public int v(String tag,
             String msg)

Description copied from interface: LogDelegate

Writes a message at level VERBOSE.

Specified by:

v in interface LogDelegate

Parameters:

tag - the tag

msg - the message

Returns:

0 if no error occurred, an error code otherwise

w

public int w(String tag,
             String msg)

Description copied from interface: LogDelegate

Writes a message at level WARN.

Specified by:

w in interface LogDelegate

Parameters:

tag - the tag

msg - the message

Returns:

0 if the message was written successfully, an error code otherwise

w

public int w(String tag,
             Throwable tr)

Description copied from interface: LogDelegate

Writes a message at level WARN.

Specified by:

w in interface LogDelegate

Parameters:

tag - the tag

tr - an exception or null

Returns:

0 if no error occurred, an error code otherwise

w

public int w(String tag,
             String msg,
             Throwable tr)

Description copied from interface: LogDelegate

Writes a message at level WARN.

Specified by:

w in interface LogDelegate

Parameters:

tag - the tag

msg - the message

tr - an exception or null

Returns:

0 if no error occurred, an error code otherwise

wtf

public int wtf(String tag,
               String msg)

Description copied from interface: LogDelegate

Writes a message at level ASSERT.

Specified by:

wtf in interface LogDelegate

Parameters:

tag - the tag

msg - the message

Returns:

0 if no error occurred, an error code otherwise

wtf

public int wtf(String tag,
               Throwable tr)

Description copied from interface: LogDelegate

Writes a message at level ASSERT.

Specified by:

wtf in interface LogDelegate

Parameters:

tag - the tag

tr - an exception or null

Returns:

0 if no error occurred, an error code otherwise

wtf

public int wtf(String tag,
               String msg,
               Throwable tr)

Description copied from interface: LogDelegate

Writes a message at level ASSERT.

Specified by:

wtf in interface LogDelegate

Parameters:

tag - the tag

msg - the message

tr - an exception or null

Returns:

0 if no error occurred, an error code otherwise