domconfigurator.java

apache的log4j源码

    Filter filter = (Filter) OptionConverter.instantiateByClassName(clazz,
                                                Filter.class, null);
    
    if(filter != null) {
      PropertySetter propSetter = new PropertySetter(filter);
      NodeList children = element.getChildNodes();
      final int length 	= children.getLength();

      for (int loop = 0; loop < length; loop++) {
	Node currentNode = children.item(loop);
	if (currentNode.getNodeType() == Node.ELEMENT_NODE) {
	  Element currentElement = (Element) currentNode;
	  String tagName = currentElement.getTagName();
	  if(tagName.equals(PARAM_TAG)) {
            setParameter(currentElement, propSetter);
	  } else {
            quietParseUnrecognizedElement(filter, currentElement, props);
      }
	}
      }
      propSetter.activate();
      LogLog.debug("Adding filter of type ["+filter.getClass()
		   +"] to appender named ["+appender.getName()+"].");
      appender.addFilter(filter);
    }    
  }
  
  /**
     Used internally to parse an category element.
  */
  protected
  void parseCategory (Element loggerElement) {
    // Create a new org.apache.log4j.Category object from the <category> element.
    String catName = subst(loggerElement.getAttribute(NAME_ATTR));

    Logger cat;    

    String className = subst(loggerElement.getAttribute(CLASS_ATTR));


    if(EMPTY_STR.equals(className)) {
      LogLog.debug("Retreiving an instance of org.apache.log4j.Logger.");
      cat = (catFactory == null) ? repository.getLogger(catName) : repository.getLogger(catName, catFactory);
    }
    else {
      LogLog.debug("Desired logger sub-class: ["+className+']');
       try {	 
	 Class clazz = Loader.loadClass(className);
	 Method getInstanceMethod = clazz.getMethod("getLogger", 
						    ONE_STRING_PARAM);
	 cat = (Logger) getInstanceMethod.invoke(null, new Object[] {catName});
       } catch (Exception oops) {
	 LogLog.error("Could not retrieve category ["+catName+
		      "]. Reported error follows.", oops);
	 return;
       }
    }

    // Setting up a category needs to be an atomic operation, in order
    // to protect potential log operations while category
    // configuration is in progress.
    synchronized(cat) {
      boolean additivity = OptionConverter.toBoolean(
                           subst(loggerElement.getAttribute(ADDITIVITY_ATTR)),
			   true);
    
      LogLog.debug("Setting ["+cat.getName()+"] additivity to ["+additivity+"].");
      cat.setAdditivity(additivity);
      parseChildrenOfLoggerElement(loggerElement, cat, false);
    }
  }


  /**
     Used internally to parse the category factory element.
  */
  protected
  void parseCategoryFactory(Element factoryElement) {
    String className = subst(factoryElement.getAttribute(CLASS_ATTR));

    if(EMPTY_STR.equals(className)) {
      LogLog.error("Category Factory tag " + CLASS_ATTR + " attribute not found.");
      LogLog.debug("No Category Factory configured.");
    }
    else {
      LogLog.debug("Desired category factory: ["+className+']');
      Object factory = OptionConverter.instantiateByClassName(className,
                                                                 LoggerFactory.class, 
                                                                 null);
      if (factory instanceof LoggerFactory) {
          catFactory = (LoggerFactory) factory;
      } else {
          LogLog.error("Category Factory class " + className + " does not implement org.apache.log4j.LoggerFactory");
      }
      PropertySetter propSetter = new PropertySetter(factory);

      Element  currentElement = null;
      Node     currentNode    = null;
      NodeList children       = factoryElement.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;
	  if (currentElement.getTagName().equals(PARAM_TAG)) {
	    setParameter(currentElement, propSetter);
	  } else {
           quietParseUnrecognizedElement(factory, currentElement, props);
      }
	}
      }
    }
  }


  /**
     Used internally to parse the roor category element.
  */
  protected
  void parseRoot (Element rootElement) {
    Logger root = repository.getRootLogger();
    // category configuration needs to be atomic
    synchronized(root) {    
      parseChildrenOfLoggerElement(rootElement, root, true);
    }
  }


  /**
     Used internally to parse the children of a category element.
  */
  protected
  void parseChildrenOfLoggerElement(Element catElement,
				      Logger cat, boolean isRoot) {
    
    PropertySetter propSetter = new PropertySetter(cat);
    
    // Remove all existing appenders from cat. They will be
    // reconstructed if need be.
    cat.removeAllAppenders();


    NodeList children 	= catElement.getChildNodes();
    final int length 	= children.getLength();
    
    for (int loop = 0; loop < length; loop++) {
      Node currentNode = children.item(loop);

      if (currentNode.getNodeType() == Node.ELEMENT_NODE) {
	Element currentElement = (Element) currentNode;
	String tagName = currentElement.getTagName();
	
	if (tagName.equals(APPENDER_REF_TAG)) {
	  Element appenderRef = (Element) currentNode;
	  Appender appender = findAppenderByReference(appenderRef);
	  String refName =  subst(appenderRef.getAttribute(REF_ATTR));
	  if(appender != null)
	    LogLog.debug("Adding appender named ["+ refName+ 
			 "] to category ["+cat.getName()+"].");
	  else 
	    LogLog.debug("Appender named ["+ refName + "] not found.");
	    
	  cat.addAppender(appender);
	  
	} else if(tagName.equals(LEVEL_TAG)) {
	  parseLevel(currentElement, cat, isRoot);	
	} else if(tagName.equals(PRIORITY_TAG)) {
	  parseLevel(currentElement, cat, isRoot);
	} else if(tagName.equals(PARAM_TAG)) {
          setParameter(currentElement, propSetter);
	} else {
        quietParseUnrecognizedElement(cat, currentElement, props);
    }
      }
    }
    propSetter.activate();
  }

  /**
     Used internally to parse a layout element.
  */  
  protected
  Layout parseLayout (Element layout_element) {
    String className = subst(layout_element.getAttribute(CLASS_ATTR));
    LogLog.debug("Parsing layout of class: \""+className+"\"");		 
    try {
      Object instance 	= Loader.loadClass(className).newInstance();
      Layout layout   	= (Layout)instance;
      PropertySetter propSetter = new PropertySetter(layout);
      
      NodeList params 	= layout_element.getChildNodes();
      final int length 	= params.getLength();

      for (int loop = 0; loop < length; loop++) {
	Node currentNode = (Node)params.item(loop);
	if (currentNode.getNodeType() == Node.ELEMENT_NODE) {
	  Element currentElement = (Element) currentNode;
	  String tagName = currentElement.getTagName();
	  if(tagName.equals(PARAM_TAG)) {
            setParameter(currentElement, propSetter);
	  } else {
          parseUnrecognizedElement(instance, currentElement, props);
      }
	}
      }
      
      propSetter.activate();
      return layout;
    }
    catch (Exception oops) {
      LogLog.error("Could not create the Layout. Reported error follows.",
		   oops);
      return null;
    }
  }

  protected 
  void parseRenderer(Element element) {
    String renderingClass = subst(element.getAttribute(RENDERING_CLASS_ATTR));
    String renderedClass = subst(element.getAttribute(RENDERED_CLASS_ATTR));
    if(repository instanceof RendererSupport) {
      RendererMap.addRenderer((RendererSupport) repository, renderedClass, 
			      renderingClass);
    }
  }

  /**
     Used internally to parse a level  element.
  */
  protected
  void parseLevel(Element element, Logger logger, boolean isRoot) {
    String catName = logger.getName();
    if(isRoot) {
      catName = "root";
    }

    String priStr = subst(element.getAttribute(VALUE_ATTR));
    LogLog.debug("Level value for "+catName+" is  ["+priStr+"].");
    
    if(INHERITED.equalsIgnoreCase(priStr) || NULL.equalsIgnoreCase(priStr)) {
      if(isRoot) {
	LogLog.error("Root level cannot be inherited. Ignoring directive.");
      } else {
	logger.setLevel(null);
      }
    } else {
      String className = subst(element.getAttribute(CLASS_ATTR));      
      if(EMPTY_STR.equals(className)) {	
	logger.setLevel(OptionConverter.toLevel(priStr, Level.DEBUG));
      } else {
	LogLog.debug("Desired Level sub-class: ["+className+']');
	try {	 
	  Class clazz = Loader.loadClass(className);
	  Method toLevelMethod = clazz.getMethod("toLevel", 
						    ONE_STRING_PARAM);
	  Level pri = (Level) toLevelMethod.invoke(null, 
						    new Object[] {priStr});
	  logger.setLevel(pri);
	} catch (Exception oops) {
	  LogLog.error("Could not create level ["+priStr+
		       "]. Reported error follows.", oops);
	  return;
	}
      }
    }
    LogLog.debug(catName + " level set to " + logger.getLevel());    
  }

  protected
  void setParameter(Element elem, PropertySetter propSetter) {
      setParameter(elem, propSetter, props);
  }


  /**
     Configure log4j using a <code>configuration</code> element as
     defined in the log4j.dtd. 

  */
  static
  public
  void configure (Element element) {
    DOMConfigurator configurator = new DOMConfigurator();
    configurator.doConfigure(element,  LogManager.getLoggerRepository());
  }

 /**
     Like {@link #configureAndWatch(String, long)} except that the
     default delay as defined by {@link FileWatchdog#DEFAULT_DELAY} is
     used. 

     @param configFilename A log4j configuration file in XML format.

  */
  static
  public
  void configureAndWatch(String configFilename) {
    configureAndWatch(configFilename, FileWatchdog.DEFAULT_DELAY);
  }

  /**
     Read the configuration file <code>configFilename</code> if it
     exists. Moreover, a thread will be created that will periodically
     check if <code>configFilename</code> has been created or
     modified. The period is determined by the <code>delay</code>
     argument. If a change or file creation is detected, then
     <code>configFilename</code> is read to configure log4j.  

      @param configFilename A log4j configuration file in XML format.
      @param delay The delay in milliseconds to wait between each check.
  */
  static
  public
  void configureAndWatch(String configFilename, long delay) {
    XMLWatchdog xdog = new XMLWatchdog(configFilename);
    xdog.setDelay(delay);
    xdog.start();
  }
  
  private interface ParseAction {
      Document parse(final DocumentBuilder parser) throws SAXException, IOException;
  }


  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);
  }
  

  public
  void doConfigure(final URL url, LoggerRepository repository) {
      ParseAction action = new ParseAction() {
          public Document parse(final DocumentBuilder parser) throws SAXException, IOException {
              return parser.parse(url.toString());
          }
          public String toString() {