Log4j中配置文件自动加载原理及非SRC下使用

public class LogManager {
  /**
   * @deprecated This variable is for internal use only. It will
   * become package protected in future versions.
   * */
  static public final String DEFAULT_CONFIGURATION_FILE = "log4j.properties";
  static final String DEFAULT_XML_CONFIGURATION_FILE = "log4j.xml";  
  /**
   * @deprecated This variable is for internal use only. It will
   * become private in future versions.
   * */
  static final public String DEFAULT_CONFIGURATION_KEY="log4j.configuration";
  /**
   * @deprecated This variable is for internal use only. It will
   * become private in future versions.
   * */
  static final public String CONFIGURATOR_CLASS_KEY="log4j.configuratorClass";
  /**
  * @deprecated This variable is for internal use only. It will
  * become private in future versions.
  */
  public static final String DEFAULT_INIT_OVERRIDE_KEY = 
"log4j.defaultInitOverride";
...//
部分静态代码块：
 static {
    // By default we use a DefaultRepositorySelector which always returns 'h'.
    Hierarchy h = new Hierarchy(new RootLogger((Level) Level.DEBUG));
    repositorySelector = new DefaultRepositorySelector(h);
    /** Search for the properties file log4j.properties in the CLASSPATH.  */
    String override =OptionConverter.getSystemProperty(DEFAULT_INIT_OVERRIDE_KEY,null);
    // if there is no default init override, then get the resource
    // specified by the user or the default config file.
    if(override == null || "false".equalsIgnoreCase(override)) {
      String configurationOptionStr = OptionConverter.getSystemProperty(
                DEFAULT_CONFIGURATION_KEY, null);
      String configuratorClassName = OptionConverter.getSystemProperty(
CONFIGURATOR_CLASS_KEY, null);
-- 注意下面的代码 -- 注意下面的代码 -- 注意下面的代码 -- 注意下面的代码
      URL url = null;
      // if the user has not specified the log4j.configuration
      // property, we search first for the file "log4j.xml" and then
      // "log4j.properties"
      if(configurationOptionStr == null) {  
    url =Loader.getResource(DEFAULT_XML_CONFIGURATION_FILE);
    if(url == null) {
      url = Loader.getResource(DEFAULT_CONFIGURATION_FILE);
    }
      } else {
      try {
        url = new URL(configurationOptionStr);
      } catch (MalformedURLException ex) {
        // so, resource is not a URL:
        // attempt to get the resource from the class path
        url = Loader.getResource(configurationOptionStr); 
      } 
      }
      ...//
 }

<!-- 设置由Sprng载入的Log4j配置文件位置 -->
<context-param>  
    <param-name>log4jConfigLocation</param-name>  
    <param-value>WEB-INF/classes/config/log4j.properties</param-value>  
</context-param>  
  <!-- Spring刷新Log4j配置文件变动的间隔,单位为毫秒 -->
<context-param>  
    <param-name>log4jRefreshInterval</param-name>  
    <param-value>10000</param-value>  
</context-param>  
<listener>  
    <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>  
</listener>