org.apache.log4j
Class PropertyConfigurator
public void doConfigure(String configFileName,
LoggerRepository hierarchy)
Read configuration from a file. The existing configuration is not cleared nor reset. If you require a different behavior, then call resetConfiguration method before calling doConfigure.
The configuration file consists of statements in the format key=value. The syntax of different configuration elements are discussed below.
Repository-wide threshold
The repository-wide threshold filters logging requests by level regardless of logger. The syntax is:
log4j.threshold=[level]
The level value can consist of the string values OFF, FATAL, ERROR, WARN, INFO, DEBUG, ALL or a custom level value. A custom level value can be specified in the form level#classname. By default the repository-wide threshold is set to the lowest possible value, namely the level ALL.
Appender configuration
Appender configuration syntax is:
# For appender named appenderName, set its class.
# Note: The appender name can contain dots.
log4j.appender.appenderName=fully.qualified.name.of.appender.class
# Set appender specific options.
log4j.appender.appenderName.option1=value1
...
log4j.appender.appenderName.optionN=valueN
For each named appender you can configure its Layout. The syntax for configuring an appender's layout is:
log4j.appender.appenderName.layout=fully.qualified.name.of.layout.class
log4j.appender.appenderName.layout.option1=value1
....
log4j.appender.appenderName.layout.optionN=valueN
The syntax for adding Filters to an appender is:
log4j.appender.appenderName.filter.ID=fully.qualified.name.of.filter.class
log4j.appender.appenderName.filter.ID.option1=value1
...
log4j.appender.appenderName.filter.ID.optionN=valueN
The first line defines the class name of the filter identified by ID; subsequent lines with the same ID specify filter option - value paris. Multiple filters are added to the appender in the lexicographic order of IDs. The syntax for adding an ErrorHandler to an appender is:
log4j.appender.appenderName.errorhandler=fully.qualified.name.of.filter.class
log4j.appender.appenderName.errorhandler.root-ref={true|false}
log4j.appender.appenderName.errorhandler.logger-ref=loggerName
log4j.appender.appenderName.errorhandler.appender-ref=appenderName
log4j.appender.appenderName.errorhandler.option1=value1
...
log4j.appender.appenderName.errorhandler.optionN=valueN
Configuring loggers
The syntax for configuring the root logger is:
log4j.rootLogger=[level], appenderName, appenderName, ...
This syntax means that an optional level can be supplied followed by appender names separated by commas.
The level value can consist of the string values OFF, FATAL, ERROR, WARN, INFO, DEBUG, ALL or a custom level value. A custom level value can be specified in the form level#classname.
If a level value is specified, then the root level is set to the corresponding level. If no level value is specified, then the root level remains untouched.
The root logger can be assigned multiple appenders.
Each appenderName (separated by commas) will be added to the root logger. The named appender is defined using the appender syntax defined above.
For non-root categories the syntax is almost the same:
log4j.logger.logger_name=[level|INHERITED|NULL], appenderName, appenderName, ...
The meaning of the optional level value is discussed above in relation to the root logger. In addition however, the value INHERITED can be specified meaning that the named logger should inherit its level from the logger hierarchy.
If no level value is supplied, then the level of the named logger remains untouched.
By default categories inherit their level from the hierarchy. However, if you set the level of a logger and later decide that that logger should inherit its level, then you should specify INHERITED as the value for the level value. NULL is a synonym for INHERITED.
Similar to the root logger syntax, each appenderName (separated by commas) will be attached to the named logger.
See the appender additivity rule in the user manual for the meaning of the additivity flag.
ObjectRenderers
You can customize the way message objects of a given type are converted to String before being logged. This is done by specifying an ObjectRenderer for the object type would like to customize.
The syntax is:
log4j.renderer.fully.qualified.name.of.rendered.class=fully.qualified.name.of.rendering.class
As in,
log4j.renderer.my.Fruit=my.FruitRenderer
ThrowableRenderer
You can customize the way an instance of Throwable is converted to String before being logged. This is done by specifying an ThrowableRenderer.
The syntax is:
log4j.throwableRenderer=fully.qualified.name.of.rendering.class
log4j.throwableRenderer.paramName=paramValue
As in,
log4j.throwableRenderer=org.apache.log4j.EnhancedThrowableRenderer
Logger Factories
The usage of custom logger factories is discouraged and no longer documented.
Resetting Hierarchy
The hierarchy will be reset before configuration when log4j.reset=true is present in the properties file.
Example
An example configuration is given below. Other configuration file examples are given in the examples folder.
# Set options for appender named "A1".
# Appender "A1" will be a SyslogAppender
log4j.appender.A1=org.apache.log4j.net.SyslogAppender
# The syslog daemon resides on www.abc.net
log4j.appender.A1.SyslogHost=www.abc.net
# A1's layout is a PatternLayout, using the conversion pattern
# %r %-5p %c{2} %M.%L %x - %m\n. Thus, the log output will
# include # the relative time since the start of the application in
# milliseconds, followed by the level of the log request,
# followed by the two rightmost components of the logger name,
# followed by the callers method name, followed by the line number,
# the nested disgnostic context and finally the message itself.
# Refer to the documentation of PatternLayout for further information
# on the syntax of the ConversionPattern key.
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%-4r %-5p %c{2} %M.%L %x - %m\n
# Set options for appender named "A2"
# A2 should be a RollingFileAppender, with maximum file size of 10 MB
# using at most one backup file. A2's layout is TTCC, using the
# ISO8061 date format with context printing enabled.
log4j.appender.A2=org.apache.log4j.RollingFileAppender
log4j.appender.A2.MaxFileSize=10MB
log4j.appender.A2.MaxBackupIndex=1
log4j.appender.A2.layout=org.apache.log4j.TTCCLayout
log4j.appender.A2.layout.ContextPrinting=enabled
log4j.appender.A2.layout.DateFormat=ISO8601
# Root logger set to DEBUG using the A2 appender defined above.
log4j.rootLogger=DEBUG, A2
# Logger definitions:
# The SECURITY logger inherits is level from root. However, it's output
# will go to A1 appender defined above. It's additivity is non-cumulative.
log4j.logger.SECURITY=INHERIT, A1
log4j.additivity.SECURITY=false
# Only warnings or above will be logged for the logger "SECURITY.access".
# Output will go to A1.
log4j.logger.SECURITY.access=WARN
# The logger "class.of.the.day" inherits its level from the
# logger hierarchy. Output will go to the appender's of the root
# logger, A2 in this case.
log4j.logger.class.of.the.day=INHERIT
Refer to the setOption method in each Appender and Layout for class specific options.
Use the # or ! characters at the beginning of a line for comments.
Parameters:
configFileName - The name of the configuration file where the configuration information is stored.
public class PatternLayout
extends Layout
A flexible layout configurable with pattern string. This code is known to have synchronization and other issues which are not present in org.apache.log4j.EnhancedPatternLayout. EnhancedPatternLayout should be used in preference to PatternLayout. EnhancedPatternLayout is distributed in the log4j extras companion.
The goal of this class is to format a LoggingEvent and return the results as a String. The results depend on the conversion pattern.
The conversion pattern is closely related to the conversion pattern of the printf function in C. A conversion pattern is composed of literal text and format control expressions calledconversion specifiers.
You are free to insert any literal text within the conversion pattern.
Each conversion specifier starts with a percent sign (%) and is followed by optional format modifiers and a conversion character. The conversion character specifies the type of data, e.g. category, priority, date, thread name. The format modifiers control such things as field width, padding, left and right justification. The following is a simple example.
Let the conversion pattern be "%-5p [%t]: %m%n" and assume that the log4j environment was set to use a PatternLayout. Then the statements
Category root = Category.getRoot(); root.debug("Message 1"); root.warn("Message 2"); would yield the output
DEBUG [main]: Message 1 WARN [main]: Message 2
Note that there is no explicit separator between text and conversion specifiers. The pattern parser knows when it has reached the end of a conversion specifier when it reads a conversion character. In the example above the conversion specifier %-5p means the priority of the logging event should be left justified to a width of five characters. The recognized conversion characters are
| Conversion Character | Effect |
|---|---|
| c | Used to output the category of the logging event. The category conversion specifier can be optionally followed by precision specifier, that is a decimal constant in brackets. If a precision specifier is given, then only the corresponding number of right most components of the category name will be printed. By default the category name is printed in full. For example, for the category name "a.b.c" the pattern %c{2} will output "b.c". |
| C | Used to output the fully qualified class name of the caller issuing the logging request. This conversion specifier can be optionally followed byprecision specifier, that is a decimal constant in brackets. If a precision specifier is given, then only the corresponding number of right most components of the class name will be printed. By default the class name is output in fully qualified form. For example, for the class name "org.apache.xyz.SomeClass", the pattern %C{1}will output "SomeClass". WARNING Generating the caller class information is slow. Thus, use should be avoided unless execution speed is not an issue. |
| d | Used to output the date of the logging event. The date conversion specifier may be followed by a date format specifier enclosed between braces. For example, %d{HH:mm:ss,SSS} or %d{dd MMM yyyy HH:mm:ss,SSS}. If no date format specifier is given then ISO8601 format is assumed. The date format specifier admits the same syntax as the time pattern string of the For better results it is recommended to use the log4j date formatters. These can be specified using one of the strings "ABSOLUTE", "DATE" and "ISO8601" for specifying These dedicated date formatters perform significantly better than |
| F | Used to output the file name where the logging request was issued. WARNING Generating caller location information is extremely slow and should be avoided unless execution speed is not an issue. |
| l | Used to output location information of the caller which generated the logging event. The location information depends on the JVM implementation but usually consists of the fully qualified name of the calling method followed by the callers source the file name and line number between parentheses. The location information can be very useful. However, its generation isextremely slow and should be avoided unless execution speed is not an issue. |
| L | Used to output the line number from where the logging request was issued. WARNING Generating caller location information is extremely slow and should be avoided unless execution speed is not an issue. |
| m | Used to output the application supplied message associated with the logging event. |
| M | Used to output the method name where the logging request was issued. WARNING Generating caller location information is extremely slow and should be avoided unless execution speed is not an issue. |
| n | Outputs the platform dependent line separator character or characters. This conversion character offers practically the same performance as using non-portable line separator strings such as "\n", or "\r\n". Thus, it is the preferred way of specifying a line separator. |
| p | Used to output the priority of the logging event. |
| r | Used to output the number of milliseconds elapsed from the construction of the layout until the creation of the logging event. |
| t | Used to output the name of the thread that generated the logging event. |
| x | Used to output the NDC (nested diagnostic context) associated with the thread that generated the logging event. |
| X | Used to output the MDC (mapped diagnostic context) associated with the thread that generated the logging event. The X conversion character must be followed by the key for the map placed between braces, as in %X{clientNumber} where See |
| % | The sequence %% outputs a single percent sign. |
By default the relevant information is output as is. However, with the aid of format modifiers it is possible to change the minimum field width, the maximum field width and justification.
The optional format modifier is placed between the percent sign and the conversion character.
The first optional format modifier is the left justification flag which is just the minus (-) character. Then comes the optional minimum field width modifier. This is a decimal constant that represents the minimum number of characters to output. If the data item requires fewer characters, it is padded on either the left or the right until the minimum width is reached. The default is to pad on the left (right justify) but you can specify right padding with the left justification flag. The padding character is space. If the data item is larger than the minimum field width, the field is expanded to accommodate the data. The value is never truncated.
This behavior can be changed using the maximum field width modifier which is designated by a period followed by a decimal constant. If the data item is longer than the maximum field, then the extra characters are removed from the beginning of the data item and not from the end. For example, it the maximum field width is eight and the data item is ten characters long, then the first two characters of the data item are dropped. This behavior deviates from the printf function in C where truncation is done from the end.
Below are various format modifier examples for the category conversion specifier.
| Format modifier | left justify | minimum width | maximum width | comment |
|---|---|---|---|---|
| %20c | false | 20 | none | Left pad with spaces if the category name is less than 20 characters long. |
| %-20c | true | 20 | none | Right pad with spaces if the category name is less than 20 characters long. |
| %.30c | NA | none | 30 | Truncate from the beginning if the category name is longer than 30 characters. |
| %20.30c | false | 20 | 30 | Left pad with spaces if the category name is shorter than 20 characters. However, if category name is longer than 30 characters, then truncate from the beginning. |
| %-20.30c | true | 20 | 30 | Right pad with spaces if the category name is shorter than 20 characters. However, if category name is longer than 30 characters, then truncate from the beginning. |
Below are some examples of conversion patterns.
%r [%t] %-5p %c %x - %m%n
This is essentially the TTCC layout.
%-6r [%15.15t] %-5p %30.30c %x - %m%n
Similar to the TTCC layout except that the relative time is right padded if less than 6 digits, thread name is right padded if less than 15 characters and truncated if longer and the category name is left padded if shorter than 30 characters and truncated if longer.
The above text is largely inspired from Peter A. Darnell and Philip E. Margolis' highly recommended book "C -- a Software Engineering Approach", ISBN 0-387-97389-3.
Since:
0.8.2
Author:
James P. Cakalic, Ceki Gülcü