标签:
基于log4j1.2.17的源代码阅读
org.apache.log4j.xml.DOMConfigurator 类是log4j的xml配置文件初始化类
org.apache.log4j.PropertyConfigurator 类是log4j的properties形式配置文件的初始化类
今天看的是前者
/** A static version of {@link #doConfigure(String, LoggerRepository)}. */ static public void configure(String filename) throws FactoryConfigurationError { new DOMConfigurator().doConfigure(filename, LogManager.getLoggerRepository()); }
一般我们都是讲log4j.xml配置文件放到与src同目录下,方便在class path 的当前路径进行查找(不能放置到src目录里面,不然打包之后也会被打包到类目录下)
public void doConfigure(final String filename, LoggerRepository repository) { ParseAction action = new ParseAction() { public Document parse(final DocumentBuilder parser) throws SAXException, IOException { return parser.parse(new File(filename)); } public String toString() { return "file [" + filename + "]"; } }; doConfigure(action, repository); }
repositroy的作用目前还没有看到
先看下是如何解析xml和初始化相关对象的。
最终会调用DOMConfigurator 类当中的方法
/** Used internally to configure the log4j framework by parsing a DOM tree of XML elements based on <a href="doc-files/log4j.dtd">log4j.dtd</a>. */ protected void parse(Element element) { String rootElementName = element.getTagName(); if (!rootElementName.equals(CONFIGURATION_TAG)) { if(rootElementName.equals(OLD_CONFIGURATION_TAG)) { LogLog.warn("The <"+OLD_CONFIGURATION_TAG+ "> element has been deprecated."); LogLog.warn("Use the <"+CONFIGURATION_TAG+"> element instead."); } else { LogLog.error("DOM element is - not a <"+CONFIGURATION_TAG+"> element."); return; } } String debugAttrib = subst(element.getAttribute(INTERNAL_DEBUG_ATTR)); LogLog.debug("debug attribute= \"" + debugAttrib +"\"."); // if the log4j.dtd is not specified in the XML file, then the // "debug" attribute is returned as the empty string. if(!debugAttrib.equals("") && !debugAttrib.equals("null")) { LogLog.setInternalDebugging(OptionConverter.toBoolean(debugAttrib, true)); } else { LogLog.debug("Ignoring " + INTERNAL_DEBUG_ATTR + " attribute."); } // // reset repository before configuration if reset="true" // on configuration element. // String resetAttrib = subst(element.getAttribute(RESET_ATTR)); LogLog.debug("reset attribute= \"" + resetAttrib +"\"."); if(!("".equals(resetAttrib))) { if (OptionConverter.toBoolean(resetAttrib, false)) { repository.resetConfiguration(); } } String confDebug = subst(element.getAttribute(CONFIG_DEBUG_ATTR)); if(!confDebug.equals("") && !confDebug.equals("null")) { LogLog.warn("The \""+CONFIG_DEBUG_ATTR+"\" attribute is deprecated."); LogLog.warn("Use the \""+INTERNAL_DEBUG_ATTR+"\" attribute instead."); LogLog.setInternalDebugging(OptionConverter.toBoolean(confDebug, true)); } String thresholdStr = subst(element.getAttribute(THRESHOLD_ATTR)); LogLog.debug("Threshold =\"" + thresholdStr +"\"."); if(!"".equals(thresholdStr) && !"null".equals(thresholdStr)) { repository.setThreshold(thresholdStr); } //Hashtable appenderBag = new Hashtable(11); /* Building Appender objects, placing them in a local namespace for future reference */ // First configure each category factory under the root element. // Category factories need to be configured before any of // categories they support. // String tagName = null; Element currentElement = null; Node currentNode = null; NodeList children = element.getChildNodes(); final int length = children.getLength(); for (int loop = 0; loop < length; loop++) { currentNode = children.item(loop); if (currentNode.getNodeType() == Node.ELEMENT_NODE) { currentElement = (Element) currentNode; tagName = currentElement.getTagName(); if (tagName.equals(CATEGORY_FACTORY_TAG) || tagName.equals(LOGGER_FACTORY_TAG)) { parseCategoryFactory(currentElement); } } } for (int loop = 0; loop < length; loop++) { currentNode = children.item(loop); if (currentNode.getNodeType() == Node.ELEMENT_NODE) { currentElement = (Element) currentNode; tagName = currentElement.getTagName(); if (tagName.equals(CATEGORY) || tagName.equals(LOGGER)) { parseCategory(currentElement); } else if (tagName.equals(ROOT_TAG)) { parseRoot(currentElement); } else if(tagName.equals(RENDERER_TAG)) { parseRenderer(currentElement); } else if(tagName.equals(THROWABLE_RENDERER_TAG)) { if (repository instanceof ThrowableRendererSupport) { ThrowableRenderer tr = parseThrowableRenderer(currentElement); if (tr != null) { ((ThrowableRendererSupport) repository).setThrowableRenderer(tr); } } } else if (!(tagName.equals(APPENDER_TAG) || tagName.equals(CATEGORY_FACTORY_TAG) || tagName.equals(LOGGER_FACTORY_TAG))) { quietParseUnrecognizedElement(repository, currentElement, props); } } } }
通过分析这个方法我们可以看到
1)log4j.xml
标签:
原文地址:http://www.cnblogs.com/wuxinliulei/p/5177201.html