/**
  * 返回日志工厂, 如果没有设置日志工厂,将创建一个默认的日志处理工厂
  *
  * @return 日志工厂
  */
 public static LogFactory getLogFactory() {
   if (logFactory != null) {
     return logFactory;
   }
   Configuration config = null;
   try {
     config = Configuration.getConfiguration();
   } catch (Exception e) {
   }
   if (config == null) {
     return new DefaultLogFactory(null);
   } else {
     configure(config);
     return logFactory;
   }
 }