Log4j 2 website. This tag library is based on the Jakarta Commons Log Taglib by Joseph Ottinger and James Strachan. For the most part, logging tags written against Jakarta Commons Log Taglib should work against this library as well. However, the "category" attribute from Jakarta has become the "logger" attribute in this library. In accordance with the org.apache.logging.log4j.Logger API, this tag library has tags to support the following logging calls: "catching", "entry", "exit", "log", "trace", "debug", "info", "warn", "error", and "fatal". The "trace" tag was not supported in Jakarta Commons Log Taglib. The "setLogger", "catching", "entry", and "trace" tags are new to this library. This tag library also supports the conditional tag "ifEnabled" (new) and troubleshooting tag "dump" (existed in Jakarta Commons Log Taglib). By default, this tag library uses a different Logger for each JSP named after the JSP ID. You can customize the Logger in any of the logging tags or the "ifEnabled" tag with the "logger" attribute. You can also use the "setLogger" tag to specify the Logger that should apply for the rest of a JSP's execution. If the "setLogger" tag comes before any other logging tags in a JSP, the default Logger for that JSP will not be created, but instead the specified logger is the only one that will be used. Every effort was made to optimize these tags and ensure decent performance, but users of this library should keep in mind that the creation and execution of JSP tags adds significant overhead to the standard Log4j method calls. While the "trace", "debug", and "info" options are available in this library, their uses are not nanosecond order of magnitude with logging off that users may be used to with standard Log4j method calls. Therefore, they should be used sparingly. Use of the "ifEnabled" tag does not improve this performance; this tag is available to conditionally evaluate other actions in addition to logging actions.]]> Log4j 2 Tag Library 1.0 log http://logging.apache.org/log4j/tld/log Sets the default Logger to use for the rest of this JSP's execution OR exports an org.apache.logging.log4j.Logger instance as the specified EL variable. The "value" attribute specifies either the String name of a Logger to create or an actual Logger instance. By default, Loggers are constructed and assigned the standard org.apache.logging.log4j.message.ParameterizedMessageFactory. The optional "factory" attribute can be used to override the default message factory. setLogger org.apache.logging.log4j.taglib.SetLoggerTag empty The name or instance of the Logger to set as the JSP's default Logger or the name of the Logger to export as the specified EL variable. logger true true java.lang.Object Specify this optional tag to provide a message factory other than the default ParameterizedMessageFactory message factory to use for the Logger. If the Logger has already been created with a different message factory, this will be ignored. Using this attribute makes no sense if the "value" attribute's value is an actual Logger instance, since its message factory cannot be changed. factory false true org.apache.logging.log4j.message.MessageFactory The optional name of the EL variable to export this Logger as. Using this attribute makes no sense if the "value" attribute's value is an actual Logger instance. That would result in an existing Logger on the scope being re-added to the scope. var false false java.lang.String Either "page," "request," "session," or "application," the optional scope that the EL variable should be exported to (defaults to "page"). scope false false java.lang.String ]]> Conditional tag that evaluates its body only if the specified log level and marker are enabled. ifEnabled org.apache.logging.log4j.taglib.IfEnabledTag JSP The name or instance of the Logger to use to override the default Logger for this JSP. logger false true java.lang.Object The name of any valid Level (TRACE, DEBUG, INFO, etc.) or an actual Level instance to check whether it is enabled. This value is case-insensitive. level true true java.lang.Object Marker data to include in the enabled check. marker false true org.apache.logging.log4j.Marker Evaluate this content Evaluate this content ]]> Equivalent of org.apache.logging.log4j.Logger#catching(). catching org.apache.logging.log4j.taglib.CatchingTag empty The name or instance of the Logger to use to override the default Logger for this JSP. logger false true java.lang.Object The name of any valid level (TRACE, DEBUG, INFO, etc.) or an actual Level instance to log this at. This value is case-insensitive and defaults to ERROR for this tag. level false true java.lang.Object The exception that should be logged. exception true true java.lang.Throwable <%= 5 / 0 %> ]]> Equivalent of org.apache.logging.log4j.Logger#entry(). This tag has dynamic attributes enabled. You may specify any number of arbitrary attributes whose values will be logged with this entry (TRACE) statement. The attribute names will be ignored. entry org.apache.logging.log4j.taglib.EntryTag empty The name or instance of the Logger to use to override the default Logger for this JSP. logger false true java.lang.Object true ]]> Equivalent of org.apache.logging.log4j.Logger#exit(). exit org.apache.logging.log4j.taglib.ExitTag empty The name or instance of the Logger to use to override the default Logger for this JSP. logger false true java.lang.Object An optional object to log with the exit (TRACE) statement. result false true java.lang.Object ]]> Equivalent of org.apache.logging.log4j.Logger#log(). This tag has dynamic attributes enabled. You may specify any number of arbitrary attributes whose values will be substituted in the String message. The "message" must be a String for this to work correctly. See the Log4j 2 manual for more information about message parameters and substitution. Only attribute values are used; attribute names are ignored. log org.apache.logging.log4j.taglib.LogTag JSP The name or instance of the Logger to use to override the default Logger for this JSP. logger false true java.lang.Object The name of any valid level (TRACE, DEBUG, INFO, etc.) or an actual Level instance to log this at. This value is case-insensitive. level true true java.lang.Object The message that should be logged. May be a String, Object, or org.apache.logging.log4j.message.Message. Either this attribute or body content are required. message false true java.lang.Object Optional marker data to include in this logging event. marker false true org.apache.logging.log4j.Marker Optional exception that should be logged. exception false true java.lang.Throwable true Log this message ]]> Equivalent of org.apache.logging.log4j.Logger#trace(). This tag has dynamic attributes enabled. You may specify any number of arbitrary attributes whose values will be substituted in the String message. The "message" must be a String for this to work correctly. See the Log4j 2 manual for more information about message parameters and substitution. Only attribute values are used; attribute names are ignored. trace org.apache.logging.log4j.taglib.TraceTag JSP The name or instance of the Logger to use to override the default Logger for this JSP. logger false true java.lang.Object The message that should be logged. May be a String, Object, or org.apache.logging.log4j.message.Message. Either this attribute or body content are required. message false true java.lang.Object Optional marker data to include in this logging event. marker false true org.apache.logging.log4j.Marker Optional exception that should be logged. exception false true java.lang.Throwable true Log this message ]]> Equivalent of org.apache.logging.log4j.Logger#debug(). This tag has dynamic attributes enabled. You may specify any number of arbitrary attributes whose values will be substituted in the String message. The "message" must be a String for this to work correctly. See the Log4j 2 manual for more information about message parameters and substitution. Only attribute values are used; attribute names are ignored. debug org.apache.logging.log4j.taglib.DebugTag JSP The name or instance of the Logger to use to override the default Logger for this JSP. logger false true java.lang.Object The message that should be logged. May be a String, Object, or org.apache.logging.log4j.message.Message. Either this attribute or body content are required. message false true java.lang.Object Optional marker data to include in this logging event. marker false true org.apache.logging.log4j.Marker Optional exception that should be logged. exception false true java.lang.Throwable true Log this message ]]> Equivalent of org.apache.logging.log4j.Logger#info(). This tag has dynamic attributes enabled. You may specify any number of arbitrary attributes whose values will be substituted in the String message. The "message" must be a String for this to work correctly. See the Log4j 2 manual for more information about message parameters and substitution. Only attribute values are used; attribute names are ignored. info org.apache.logging.log4j.taglib.InfoTag JSP The name or instance of the Logger to use to override the default Logger for this JSP. logger false true java.lang.Object The message that should be logged. May be a String, Object, or org.apache.logging.log4j.message.Message. Either this attribute or body content are required. message false true java.lang.Object Optional marker data to include in this logging event. marker false true org.apache.logging.log4j.Marker Optional exception that should be logged. exception false true java.lang.Throwable true Log this message ]]> Equivalent of org.apache.logging.log4j.Logger#warn(). This tag has dynamic attributes enabled. You may specify any number of arbitrary attributes whose values will be substituted in the String message. The "message" must be a String for this to work correctly. See the Log4j 2 manual for more information about message parameters and substitution. Only attribute values are used; attribute names are ignored. warn org.apache.logging.log4j.taglib.WarnTag JSP The name or instance of the Logger to use to override the default Logger for this JSP. logger false true java.lang.Object The message that should be logged. May be a String, Object, or org.apache.logging.log4j.message.Message. Either this attribute or body content are required. message false true java.lang.Object Optional marker data to include in this logging event. marker false true org.apache.logging.log4j.Marker Optional exception that should be logged. exception false true java.lang.Throwable true Log this message ]]> Equivalent of org.apache.logging.log4j.Logger#error(). This tag has dynamic attributes enabled. You may specify any number of arbitrary attributes whose values will be substituted in the String message. The "message" must be a String for this to work correctly. See the Log4j 2 manual for more information about message parameters and substitution. Only attribute values are used; attribute names are ignored. error org.apache.logging.log4j.taglib.ErrorTag JSP The name or instance of the Logger to use to override the default Logger for this JSP. logger false true java.lang.Object The message that should be logged. May be a String, Object, or org.apache.logging.log4j.message.Message. Either this attribute or body content are required. message false true java.lang.Object Optional marker data to include in this logging event. marker false true org.apache.logging.log4j.Marker Optional exception that should be logged. exception false true java.lang.Throwable true Log this message ]]> Equivalent of org.apache.logging.log4j.Logger#fatal(). This tag has dynamic attributes enabled. You may specify any number of arbitrary attributes whose values will be substituted in the String message. The "message" must be a String for this to work correctly. See the Log4j 2 manual for more information about message parameters and substitution. Only attribute values are used; attribute names are ignored. fatal org.apache.logging.log4j.taglib.FatalTag JSP The name or instance of the Logger to use to override the default Logger for this JSP. logger false true java.lang.Object The message that should be logged. May be a String, Object, or org.apache.logging.log4j.message.Message. Either this attribute or body content are required. message false true java.lang.Object Optional marker data to include in this logging event. marker false true org.apache.logging.log4j.Marker Optional exception that should be logged. exception false true java.lang.Throwable true Log this message ]]> Displays all variables bound to the specified scope. dump org.apache.logging.log4j.taglib.DumpTag empty Either "page," "request," "session," or "application," the scope whose bound variables should be dumped onto the page inline. scope true false java.lang.String ]]>