Yii::log($message, $level, $category);
Yii::trace($message, $category);

defined('YII_DEBUG') or define('YII_DEBUG', true);

array(
    ......
    'preload'=>array('log'),
    'components'=>array(
        ......
 'log'=>array(  'class'=>'CLogRouter',  'routes'=>array(  array(  'class'=>'CFileLogRoute',  'levels'=>'trace, info',  'categories'=>'system.*',  ),  array(  'class'=>'CEmailLogRoute',  'levels'=>'error, warning',  'emails'=>'admin@example.com',  ),  ),  ),  ), ) 

/**
 * Writes a trace message.
 * This method will only log a message when the application is in debug mode.
 * @param string $msg message to be logged
 * @param string $category category of the message
 * @see log  */ public static function trace($msg,$category='application') {  // 得先定义常量YII_DEBUG为true  if(YII_DEBUG)  // CLogger::LEVEL_TRACE  self::log($msg,CLogger::LEVEL_TRACE,$category); } /**  * Logs a message.  * Messages logged by this method may be retrieved via {@link CLogger::getLogs}  * and may be recorded in different media, such as file, email, database, using  * {@link CLogRouter}.  * @param string $msg message to be logged  * @param string $level level of the message (e.g. 'trace', 'warning', 'error'). It is case-insensitive.  * @param string $category category of the message (e.g. 'system.web'). It is case-insensitive.  */ public static function log($msg,$level=CLogger::LEVEL_INFO,$category='application') {  if(self::$_logger===null)  self::$_logger=new CLogger;  // 注意这里的常量YII_TRACE_LEVEL，如果想日志中含有对应文件名、对应行，那么应该定义YII_TRACE_LEVEL大于0，  // 这个常量的意思应该是日志追踪的深度  if(YII_DEBUG && YII_TRACE_LEVEL>0 && $level!==CLogger::LEVEL_PROFILE)  {  $traces=debug_backtrace();  $count=0;  foreach($traces as $trace)  {  if(isset($trace['file'],$trace['line']) && strpos($trace['file'],YII_PATH)!==0)  {  $msg.="\nin ".$trace['file'].' ('.$trace['line'].')';  if(++$count>=YII_TRACE_LEVEL)  break;  }  }  }  // 调用的是CLogger类的log方法  self::$_logger->log($msg,$level,$category); } 

/**
 * Logs a message.
 * Messages logged by this method may be retrieved back via {@link getLogs}.
 * @param string $message message to be logged
 * @param string $level level of the message (e.g. 'Trace', 'Warning', 'Error'). It is case-insensitive.
 * @param string $category category of the message (e.g. 'system.web'). It is case-insensitive.  * @see getLogs  */ public function log($message,$level='info',$category='application') {  $this->_logs[]=array($message,$level,$category,microtime(true));  $this->_logCount++;  // autoFlush的默认值为10000，即只有当日志的条数达到10000（或请求处理结束时），才会flush到输出，否则一直将日志存放在内存中  if($this->autoFlush>0 && $this->_logCount>=$this->autoFlush && !$this->_processing)  {  $this->_processing=true;  // autoDump默认为false  $this->flush($this->autoDump);  $this->_processing=false;  } } 

/**
 * Removes all recorded messages from the memory.
 * This method will raise an {@link onFlush} event.
 * The attached event handlers can process the log messages before they are removed.
 * @param boolean $dumpLogs whether to process the logs immediately as they are passed to log route
 * @since 1.1.0  */ public function flush($dumpLogs=false) {  // 事件对象中会带有当前的CLogger对象，作为事件的发送者  // 但在类CLogRouter的方法collectLogs和processLogs中并没有使用这个CLogger对象，  // 而是通过Yii::getLogger()来得到同一个CLogger对象，为什么不直接使用呢？  $this->onFlush(new CEvent($this, array('dumpLogs'=>$dumpLogs)));  // 清空重置  $this->_logs=array();  $this->_logCount=0; } /**  * Raises an <code>onFlush</code> event.  * @param CEvent $event the event parameter  * @since 1.1.0  */ public function onFlush($event) {  // 抛出onFlush事件  // raiseEvent方法定义在CComponent类中，CLogger类继承自CComponent类  $this->raiseEvent('onFlush', $event); } 

/**
 * Raises an event.
 * This method represents the happening of an event. It invokes
 * all attached handlers for the event.
 * @param string $name the event name
 * @param CEvent $event the event parameter  * @throws CException if the event is undefined or an event handler is invalid.  */ public function raiseEvent($name,$event) {  $name=strtolower($name);  if(isset($this->_e[$name]))  {  // 逐个执行与事件$name绑定的$handler  foreach($this->_e[$name] as $handler)  {  if(is_string($handler))  // 会将事件对象(CEvent对象)传到$handler中  call_user_func($handler,$event);  elseif(is_callable($handler,true))  {  if(is_array($handler))  {  // an array: 0 - object, 1 - method name  list($object,$method)=$handler;  if(is_string($object)) // static method call  call_user_func($handler,$event);  elseif(method_exists($object,$method))  $object->$method($event);  else  throw new CException(Yii::t('yii','Event "{class}.{event}" is attached with an invalid handler "{handler}".',  array('{class}'=>get_class($this), '{event}'=>$name, '{handler}'=>$handler[1])));  }  else // PHP 5.3: anonymous function  call_user_func($handler,$event);  }  else  throw new CException(Yii::t('yii','Event "{class}.{event}" is attached with an invalid handler "{handler}".',  array('{class}'=>get_class($this), '{event}'=>$name, '{handler}'=>gettype($handler))));  // stop further handling if param.handled is set true  if(($event instanceof CEvent) && $event->handled)  return;  }  }  elseif(YII_DEBUG && !$this->hasEvent($name))  throw new CException(Yii::t('yii','Event "{class}.{event}" is not defined.',  array('{class}'=>get_class($this), '{event}'=>$name))); } 

/**
 * Initializes this application component.
 * This method is required by the IApplicationComponent interface.
 */
public function init()
{  parent::init();  // 实例化配置的routes参数中指定的日志路由类列表  foreach($this->_routes as $name=>$route)  {  $route=Yii::createComponent($route);  $route->init();  $this->_routes[$name]=$route;  }  // 将当前对象的collectLogs方法绑定到事件onFlush  Yii::getLogger()->attachEventHandler('onFlush',array($this,'collectLogs'));  // 将当前对象的processLogs方法绑定到事件onEndRequest（表示请求处理结束？）  Yii::app()->attachEventHandler('onEndRequest',array($this,'processLogs')); } 

/**
 * Collects log messages from a logger.
 * This method is an event handler to the {@link CLogger::onFlush} event.
 * @param CEvent $event event parameter
 */
public function collectLogs($event) {  $logger=Yii::getLogger();  $dumpLogs=isset($event->params['dumpLogs']) && $event->params['dumpLogs'];  // 遍历所有日志路由对象，执行其方法collectLogs  foreach($this->_routes as $route)  {  // 属性enabled默认值为true  if($route->enabled)  // $dumpLogs默认为false，由事件对象传过来  $route->collectLogs($logger,$dumpLogs);  } } /**  * Collects and processes log messages from a logger.  * This method is an event handler to the {@link CApplication::onEndRequest} event.  * @param CEvent $event event parameter  * @since 1.1.0  */ public function processLogs($event) {  $logger=Yii::getLogger();  // 遍历所有日志路由对象，执行其方法collectLogs  foreach($this->_routes as $route)  {  if($route->enabled)  // 注意这里参数$dumpLogs参数值始终为true  $route->collectLogs($logger,true);  } } 

/**
 * Retrieves filtered log messages from logger for further processing.
 * @param CLogger $logger logger instance
 * @param boolean $processLogs whether to process the logs after they are collected from the logger
 */
// 事件onFlush触发时，传入的$processLogs参数值默认为false，事件onEndRequest触发时为true public function collectLogs($logger, $processLogs=false) {  // 从类CLogger实例化对象的_logs属性值中过滤得到目标日志记录  $logs=$logger->getLogs($this->levels,$this->categories,$this->except);  $this->logs=empty($this->logs) ? $logs : array_merge($this->logs,$logs);  if($processLogs && !empty($this->logs))  {  if($this->filter!==null)  Yii::createComponent($this->filter)->filter($this->logs);  if($this->logs!==array())  // 调用实际route的processLogs方法  $this->processLogs($this->logs);  $this->logs=array();  } } 

/**
 * Displays the log messages.
 * @param array $logs list of log messages
 */
public function processLogs($logs)
{  $this->render('log',$logs); } /**  * Renders the view.  * @param string $view the view name (file name without extension). The file is assumed to be located under framework/data/views.  * @param array $data data to be passed to the view  */ protected function render($view,$data) {  $app=Yii::app();  $isAjax=$app->getRequest()->getIsAjaxRequest();  $isFlash=$app->getRequest()->getIsFlashRequest();  // 用firebug来显示日志信息的话？  if($this->showInFireBug)  {  // do not output anything for ajax and/or flash requests if needed  if($isAjax && $this->ignoreAjaxInFireBug || $isFlash && $this->ignoreFlashInFireBug)  return;  $view.='-firebug';  if(($userAgent=$app->getRequest()->getUserAgent())!==null && preg_match('/msie [5-9]/i',$userAgent))  {  echo '<script type="text/javascript">';  echo file_get_contents(dirname(__FILE__).'/../vendors/console-normalizer/normalizeconsole.min.js');  echo "</script>\n";  }  }  elseif(!($app instanceof CWebApplication) || $isAjax || $isFlash)  return;  // 渲染yii/framework/views/log.php（log-firebug.php），将结果放在实际请求页面内容的下面  $viewFile=YII_PATH.DIRECTORY_SEPARATOR.'views'.DIRECTORY_SEPARATOR.$view.'.php';  include($app->findLocalizedFile($viewFile,'en')); } 

public function attachEventHandler($name,$handler)
{
    // 将事件处理器$handler加到处理器列表中，在事件发生时会逐个处理器触发执行
    $this->getEventHandlers($name)->add($handler);
}

/**
 * Returns the list of attached event handlers for an event.
 * @param string $name the event name
 * @return CList list of attached event handlers for the event
 * @throws CException if the event is not defined
 */ public function getEventHandlers($name) {  if($this->hasEvent($name))  {  $name=strtolower($name);  if(!isset($this->_e[$name]))  $this->_e[$name]=new CList;  return $this->_e[$name];  }  else  throw new CException(Yii::t('yii','Event "{class}.{event}" is not defined.',  array('{class}'=>get_class($this), '{event}'=>$name))); }