log4j 1.x
https://logging.apache.org/log4j/1.2/manual.html
1. log4j.dtd 在哪里？
log4j.jar 包中 org.apache.log4j.xml 下
<?xml version="1.0" encoding="UTF-8" ?>
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<!-- Authors: Chris Taylor, Ceki Gulcu. -->
<!-- Version: 1.2 -->
<!-- A configuration element consists of optional renderer
elements,appender elements, categories and an optional root
element. -->
<!ELEMENT log4j:configuration (renderer*, throwableRenderer?,
appender*,plugin*, (category|logger)*,root?,
(categoryFactory|loggerFactory)?)>
<!-- The "threshold" attribute takes a level value below which -->
<!-- all logging statements are disabled. -->
<!-- Setting the "debug" enable the printing of internal log4j logging -->
<!-- statements. -->
<!-- By default, debug attribute is "null", meaning that we not do touch -->
<!-- internal log4j logging settings. The "null" value for the threshold -->
<!-- attribute can be misleading. The threshold field of a repository -->
<!-- cannot be set to null. The "null" value for the threshold attribute -->
<!-- simply means don't touch the threshold field, the threshold field -->
<!-- keeps its old value. -->
<!ATTLIST log4j:configuration
xmlns:log4j CDATA #FIXED "http://jakarta.apache.org/log4j/"
threshold (all|trace|debug|info|warn|error|fatal|off|null) "null"
debug (true|false|null) "null"
reset (true|false) "false"
>
<!-- renderer elements allow the user to customize the conversion of -->
<!-- message objects to String. -->
<!ELEMENT renderer EMPTY>
<!ATTLIST renderer
renderedClass CDATA #REQUIRED
renderingClass CDATA #REQUIRED
>
<!-- throwableRenderer allows the user to customize the conversion
of exceptions to a string representation. -->
<!ELEMENT throwableRenderer (param*)>
<!ATTLIST throwableRenderer
class CDATA #REQUIRED
>
<!-- Appenders must have a name and a class. -->
<!-- Appenders may contain an error handler, a layout, optional parameters -->
<!-- and filters. They may also reference (or include) other appenders. -->
<!ELEMENT appender (errorHandler?, param*,
rollingPolicy?, triggeringPolicy?, connectionSource?,
layout?, filter*, appender-ref*)>
<!ATTLIST appender
name CDATA #REQUIRED
class CDATA #REQUIRED
>
<!ELEMENT layout (param*)>
<!ATTLIST layout
class CDATA #REQUIRED
>
<!ELEMENT filter (param*)>
<!ATTLIST filter
class CDATA #REQUIRED
>
<!-- ErrorHandlers can be of any class. They can admit any number of -->
<!-- parameters. -->
<!ELEMENT errorHandler (param*, root-ref?, logger-ref*, appender-ref?)>
<!ATTLIST errorHandler
class CDATA #REQUIRED
>
<!ELEMENT root-ref EMPTY>
<!ELEMENT logger-ref EMPTY>
<!ATTLIST logger-ref
ref CDATA #REQUIRED
>
<!ELEMENT param EMPTY>
<!ATTLIST param
name CDATA #REQUIRED
value CDATA #REQUIRED
>
<!-- The priority class is org.apache.log4j.Level by default -->
<!ELEMENT priority (param*)>
<!ATTLIST priority
class CDATA #IMPLIED
value CDATA #REQUIRED
>
<!-- The level class is org.apache.log4j.Level by default -->
<!ELEMENT level (param*)>
<!ATTLIST level
class CDATA #IMPLIED
value CDATA #REQUIRED
>
<!-- If no level element is specified, then the configurator MUST not -->
<!-- touch the level of the named category. -->
<!ELEMENT category (param*,(priority|level)?,appender-ref*)>
<!ATTLIST category
class CDATA #IMPLIED
name CDATA #REQUIRED
additivity (true|false) "true"
>
<!-- If no level element is specified, then the configurator MUST not -->
<!-- touch the level of the named logger. -->
<!ELEMENT logger (param*,level?,appender-ref*)>
<!ATTLIST logger
class CDATA #IMPLIED
name CDATA #REQUIRED
additivity (true|false) "true"
>
<!ELEMENT categoryFactory (param*)>
<!ATTLIST categoryFactory
class CDATA #REQUIRED>
<!ELEMENT loggerFactory (param*)>
<!ATTLIST loggerFactory
class CDATA #REQUIRED>
<!ELEMENT appender-ref EMPTY>
<!ATTLIST appender-ref
ref CDATA #REQUIRED
>
<!-- plugins must have a name and class and can have optional parameters -->
<!ELEMENT plugin (param*, connectionSource?)>
<!ATTLIST plugin
name CDATA #REQUIRED
class CDATA #REQUIRED
>
<!ELEMENT connectionSource (dataSource?, param*)>
<!ATTLIST connectionSource
class CDATA #REQUIRED
>
<!ELEMENT dataSource (param*)>
<!ATTLIST dataSource
class CDATA #REQUIRED
>
<!ELEMENT triggeringPolicy ((param|filter)*)>
<!ATTLIST triggeringPolicy
name CDATA #IMPLIED
class CDATA #REQUIRED
>
<!ELEMENT rollingPolicy (param*)>
<!ATTLIST rollingPolicy
name CDATA #IMPLIED
class CDATA #REQUIRED
>
<!-- If no priority element is specified, then the configurator MUST not -->
<!-- touch the priority of root. -->
<!-- The root category always exists and cannot be subclassed. -->
<!ELEMENT root (param*, (priority|level)?, appender-ref*)>
<!-- ==================================================================== -->
<!-- A logging event -->
<!-- ==================================================================== -->
<!ELEMENT log4j:eventSet (log4j:event*)>
<!ATTLIST log4j:eventSet
xmlns:log4j CDATA #FIXED "http://jakarta.apache.org/log4j/"
version (1.1|1.2) "1.2"
includesLocationInfo (true|false) "true"
>
<!ELEMENT log4j:event (log4j:message, log4j:NDC?, log4j:throwable?,
log4j:locationInfo?, log4j:properties?) >
<!-- The timestamp format is application dependent. -->
<!ATTLIST log4j:event
logger CDATA #REQUIRED
level CDATA #REQUIRED
thread CDATA #REQUIRED
timestamp CDATA #REQUIRED
time CDATA #IMPLIED
>
<!ELEMENT log4j:message (#PCDATA)>
<!ELEMENT log4j:NDC (#PCDATA)>
<!ELEMENT log4j:throwable (#PCDATA)>
<!ELEMENT log4j:locationInfo EMPTY>
<!ATTLIST log4j:locationInfo
class CDATA #REQUIRED
method CDATA #REQUIRED
file CDATA #REQUIRED
line CDATA #REQUIRED
>
<!ELEMENT log4j:properties (log4j:data*)>
<!ELEMENT log4j:data EMPTY>
<!ATTLIST log4j:data
name CDATA #REQUIRED
value CDATA #REQUIRED
>
2. category和logger ，priority和level 区别？
This class has been deprecated and replaced by the Logger subclass.
Refrain from using this class directly, use the
Level class instead.父子类关系，相同的效果，但避免使用Category 和 Priority
<!ELEMENT log4j:configuration (renderer*, appender*, plugin*, (category | logger)*, root?, (categoryFactory | loggerFactory)?)>
<!ELEMENT category (param*, (priority | level)?, appender-ref*)>
二选一，如果都出现会提示错误 log4j:WARN The content of element type "root" must match "(param*,(priority|level)?,appender-ref*)".
另外logger 中只能使用level （这是新的，新的里面当然不会使用老的，老的最终是要被淘汰的）
3. additivity
<!ATTLIST logger
name CDATA #REQUIRED
additivity (true | false) "true"
>
当匹配的一个最合适的logger（最具体的），同过additivity 控制是否向上蔓延，默认true
4. 继承
Level Inheritance
The inherited level for a given logger C, is equal to the first non-null level in the logger hierarchy, starting at C and proceeding upwards in the hierarchy towards the root logger.
从最具体的匹配开始，如果没有指定level则会继承第一个非空的祖先的level
Example 1
| Logger name | Assigned level | Inherited level |
|---|---|---|
| root | Proot | Proot |
| X | none | Proot |
| X.Y | none | Proot |
| X.Y.Z | none | Proot |
In example 1 above, only the root logger is assigned a level. This level value, Proot, is inherited by the other loggers X, X.Y and X.Y.Z.
Example 2
| Logger name | Assigned level | Inherited level |
|---|---|---|
| root | Proot | Proot |
| X | Px | Px |
| X.Y | Pxy | Pxy |
| X.Y.Z | Pxyz | Pxyz |
In example 2, all loggers have an assigned level value. There is no need for level inheritence.
Example 3
| Logger name | Assigned level | Inherited level |
|---|---|---|
| root | Proot | Proot |
| X | Px | Px |
| X.Y | none | Px |
| X.Y.Z | Pxyz | Pxyz |
In example 3, the loggers root, X and X.Y.Z are assigned the levels Proot, Px and Pxyz respectively. The logger X.Y inherits its level value from its parent X.
| Logger name | Assigned level | Inherited level |
|---|---|---|
| root | Proot | Proot |
| X | Px | Px |
| X.Y | none | Px |
| X.Y.Z | none | Px |
5. 具体例子
<dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.17</version> </dependency>
log4j.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE log4j:configuration SYSTEM "log4j.dtd"> <log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/" debug="false"> <!-- fileAppender --> <appender name="fileAppender" class="org.apache.log4j.RollingFileAppender"> <param name="File" value="logs/test.log" /> <param name="Append" value="true" /> <param name="MaxFileSize" value="5000KB" /> <param name="MaxBackupIndex" value="10" /> <param name="encoding" value="UTF-8" /> <layout class="org.apache.log4j.PatternLayout"> <param name="ConversionPattern" value="%d{MM/dd HH:mm:ss,SSS} [%c:%M:%-3L]-[%-5p] %m%n" /> </layout> </appender> <logger name="a" additivity="true"> <level value="INFO" /> <appender-ref ref="fileAppender" /> </logger> <logger name="a.b" additivity="true"> <level value="DEBUG" /> <appender-ref ref="fileAppender" /> </logger> <root> <level value="ERROR" /> <appender-ref ref="fileAppender" /> </root> </log4j:configuration>
package a; import org.apache.log4j.Logger; public class A { private static final Logger logger = Logger.getLogger(A.class); public void ff(){ logger.trace(logger.getLevel()); logger.debug(logger.getLevel()); logger.info(logger.getLevel()); logger.warn(logger.getLevel()); logger.error(logger.getLevel()); } }
package a.b; import org.apache.log4j.Logger; public class AB { private static final Logger logger = Logger.getLogger(AB.class); public void ff(){ logger.trace(logger.getLevel()); logger.debug(logger.getLevel()); logger.info(logger.getLevel()); logger.warn(logger.getLevel()); logger.error(logger.getLevel()); } }
import a.A; import a.b.AB; public class Test { public static void main(String[] args) { new A().ff(); new AB().ff(); } }
打印结果：
02/07 12:16:20,033 [a.A:ff:11 ]-[INFO ] 02/07 12:16:20,033 [a.A:ff:11 ]-[INFO ] 02/07 12:16:20,036 [a.A:ff:12 ]-[WARN ] 02/07 12:16:20,036 [a.A:ff:12 ]-[WARN ] 02/07 12:16:20,036 [a.A:ff:13 ]-[ERROR] 02/07 12:16:20,036 [a.A:ff:13 ]-[ERROR] 02/07 12:16:20,036 [a.b.AB:ff:10 ]-[DEBUG] 02/07 12:16:20,036 [a.b.AB:ff:10 ]-[DEBUG] 02/07 12:16:20,036 [a.b.AB:ff:10 ]-[DEBUG] 02/07 12:16:20,036 [a.b.AB:ff:11 ]-[INFO ] 02/07 12:16:20,036 [a.b.AB:ff:11 ]-[INFO ] 02/07 12:16:20,036 [a.b.AB:ff:11 ]-[INFO ] 02/07 12:16:20,036 [a.b.AB:ff:12 ]-[WARN ] 02/07 12:16:20,036 [a.b.AB:ff:12 ]-[WARN ] 02/07 12:16:20,036 [a.b.AB:ff:12 ]-[WARN ] 02/07 12:16:20,038 [a.b.AB:ff:13 ]-[ERROR] 02/07 12:16:20,038 [a.b.AB:ff:13 ]-[ERROR] 02/07 12:16:20,038 [a.b.AB:ff:13 ]-[ERROR]
6. 开启自身内部的调试信息
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/" debug="true">
打印结果：
log4j: reset attribute= "false".
log4j: Threshold ="null".
log4j: Retreiving an instance of org.apache.log4j.Logger.
log4j: Setting [a] additivity to [true].
log4j: Level value for a is [INFO].
log4j: a level set to INFO
log4j: Class name: [org.apache.log4j.RollingFileAppender]
log4j: Setting property [file] to [logs/test.log].
log4j: Setting property [append] to [true].
log4j: Setting property [maxFileSize] to [5000KB].
log4j: Setting property [maxBackupIndex] to [10].
log4j: Setting property [encoding] to [UTF-8].
log4j: Parsing layout of class: "org.apache.log4j.PatternLayout"
log4j: Setting property [conversionPattern] to [%d{MM/dd HH:mm:ss,SSS} [%c:%M:%-3L]-[%-5p] %m%n].
log4j: setFile called: logs/test.log, true
log4j: setFile ended
log4j: Adding appender named [fileAppender] to category [a].
log4j: Retreiving an instance of org.apache.log4j.Logger.
log4j: Setting [a.b] additivity to [true].
log4j: Level value for a.b is [DEBUG].
log4j: a.b level set to DEBUG
log4j: Adding appender named [fileAppender] to category [a.b].
log4j: Level value for root is [ERROR].
log4j: root level set to ERROR
log4j: Adding appender named [fileAppender] to category [root].
