apache-comnons系列之commons-logging1.2 学习笔记
概述
参考
http://blog.csdn.net/linshuhe1/article/details/53761571
Log
A simple logging interface abstracting logging APIs. In order to be instantiated successfully by {@link LogFactory}, classes that implementthis interface must have a constructor that takes a single String parameter representing the “name” of this Logtrace/debug/info/warn/error/fatal
LogFactory
Factory for creating {@link Log} instances, with discovery and configuration features similar to that employed by standard Java APIs such as JAXP.org.apache.commons.logging.LogFactory.getFactory
The org.apache.commons.logging.LogFactory system property.The JDK 1.3 Service Discovery mechanismUse the properties file commons-logging.propertiesFall back to a default implementation class (org.apache.commons.logging.impl.LogFactoryImpl)
LogFactoryImpl
instances = new Hashtable();—->拥有存放创建的Logattributes = new Hashtable();—->用于存放加载的属性classesToDiscover—->存放相关Log实现类数组(Log4JLogger/Jdk14Logger/Jdk13LumberjackLogger/SimpleLog)org.apache.commons.logging.impl.LogFactoryImpl.getInstance(java.lang.String)
org.apache.commons.logging.impl.LogFactoryImpl#discoverLogImplementation—->查找Log的实现
Attempts to create a Log instance for the given category name.Follows the discovery process described in the class javadoc.org.apache.commons.logging.impl.LogFactoryImpl#findUserSpecifiedLogClassName(查找是否有设定org.apache.commons.logging.Log属性)Checks system properties and the attribute map for a Log implementation specified by the user under the property names {@link #LOG_PROPERTY} or {@link #LOG_PROPERTY_OLD}createLogFromClass—->通过类路径查找相关实现类从classesToDiscover数组中查找相关实现类,第一个为Log4JLogger,相关加载过程如下
Log4JLogger
Implementation of {@link Log} that maps directly to a Logger for log4J version 1.2.org.apache.log4j.Logger logger—->Log to this loggerString name—->Logger nameorg.apache.commons.logging.impl.Log4JLogger.getLogger
LogManager.getLoggerorg.apache.log4j.LogManager
Use the LogManager class to retreive {@link Logger} instances or to operate on the current {@link LoggerRepository}static{}—->静态初始化块,进行RootLogger、以及log4j配置文件的加载OptionConverter.selectAndConfigure—->Configure log4j given a URLorg.apache.log4j.PropertyConfigurator.doConfigure(java.net.URL, org.apache.log4j.spi.LoggerRepository)
configureRootCategory(properties, hierarchy);configureLoggerFactory(properties);parseCatsAndRenderers(properties, hierarchy);
Jdk14Logger
Implementation of the org.apache.commons.logging.Log interface that wraps the standard JDK logging mechanisms that were introduced in the Merlin release
测试
org.apache.commons.logging.LogTestCase
LogFactory.getLog(this.getClass().getName())—->加载过程
getFactory().getInstance(name)—->加载LogFactory与配置文件comomns.properties/log4j.properties文件如上所述看下如何创建我们传入的Logger对象instance = (Log) logConstructor.newInstance(params);
反转调用public Log4JLogger(String name)org.apache.commons.logging.impl.Log4JLogger.getLoggerorg.apache.log4j.Hierarchy.getLogger(java.lang.String, org.apache.log4j.spi.LoggerFactory)
logger = factory.makeNewLoggerInstance(name);—->利用工厂创建Loggerlogger.setHierarchy(this);—->创建Logger层次ht.put(key, logger);—->存放缓存的LoggerupdateParents(logger);—->更新创建的Logger的父类
