About the logging function in the Yii framework of PHP

'log'=>array(
    'class'=>'CLogRouter',
    'routes'=>array(
      array(
        'class'=>'CFileLogRoute',
        'levels'=>'error, warning',

      ),
              // 下面显示页面日志 
              array( 
               'class'=>'CWebLogRoute', 
               'levels'=>'trace',  //级别为trace 
               'categories'=>'system.db.*' //只显示关于数据库信息,包括数据库连接,数据库执行语句 
              ), 
      // uncomment the following to show log messages on web pages
      /*
      array(
        'class'=>'CWebLogRoute',
      ),
      */
    ),
  ),

 <?php

/**
 * author   : forecho <caizhenghai@gmail.com>
 * createTime : 2015/12/22 18:13
 * description:
 */
namespace common\components;

use Yii;
use yii\helpers\FileHelper;

class FileTarget extends \yii\log\FileTarget
{
  /**
   * @var bool 是否启用日志前缀 (@app/runtime/logs/error/20151223_app.log)
   */
  public $enableDatePrefix = false;

  /**
   * @var bool 启用日志等级目录
   */
  public $enableCategoryDir = false;

  private $_logFilePath = &#39;&#39;;

  public function init()
  {
    if ($this->logFile === null) {
      $this->logFile = Yii::$app->getRuntimePath() . &#39;/logs/app.log&#39;;
    } else {
      $this->logFile = Yii::getAlias($this->logFile);
    }
    $this->_logFilePath = dirname($this->logFile);

    // 启用日志前缀
    if ($this->enableDatePrefix) {
      $filename = basename($this->logFile);
      $this->logFile = $this->_logFilePath . &#39;/&#39; . date(&#39;Ymd&#39;) . &#39;_&#39; . $filename;
    }

    if (!is_dir($this->_logFilePath)) {
      FileHelper::createDirectory($this->_logFilePath, $this->dirMode, true);
    }

    if ($this->maxLogFiles < 1) {
      $this->maxLogFiles = 1;
    }
    if ($this->maxFileSize < 1) {
      $this->maxFileSize = 1;
    }

  }
}

'components' => [
  'log' => [
    'traceLevel' => YII_DEBUG ? 3 : 0,
    'targets' => [
      /**
       * 错误级别日志：当某些需要立马解决的致命问题发生的时候，调用此方法记录相关信息。
       * 使用方法：Yii::error()
       */
      [
        'class' => 'common\components\FileTarget',
        // 日志等级
        'levels' => ['error'],
        // 被收集记录的额外数据
        'logVars' => ['_GET', '_POST', '_FILES', '_COOKIE', '_SESSION','_SERVER'],
        // 指定日志保存的文件名
        'logFile' => '@app/runtime/logs/error/app.log',
        // 是否开启日志 (@app/runtime/logs/error/20151223_app.log)
        'enableDatePrefix' => true,
        'maxFileSize' => 1024 * 1,
        'maxLogFiles' => 100,
      ],
      /**
       * 警告级别日志：当某些期望之外的事情发生的时候，使用该方法。
       * 使用方法：Yii::warning()
       */
      [
        'class' => 'common\components\FileTarget',
        // 日志等级
        'levels' => ['warning'],
        // 被收集记录的额外数据
        'logVars' => ['_GET', '_POST', '_FILES', '_COOKIE', '_SESSION','_SERVER'],
        // 指定日志保存的文件名
        'logFile' => '@app/runtime/logs/warning/app.log',
        // 是否开启日志 (@app/runtime/logs/warning/20151223_app.log)
        'enableDatePrefix' => true,
        'maxFileSize' => 1024 * 1,
        'maxLogFiles' => 100,
      ],
      /**
       * info 级别日志：在某些位置记录一些比较有用的信息的时候使用。
       * 使用方法：Yii::info()
       */
      [
        'class' => 'common\components\FileTarget',
        // 日志等级
        'levels' => ['info'],
        // 被收集记录的额外数据
        'logVars' => ['_GET', '_POST', '_FILES', '_COOKIE', '_SESSION','_SERVER'],
        // 指定日志保存的文件名
        'logFile' => '@app/runtime/logs/info/app.log',
        // 是否开启日志 (@app/runtime/logs/info/20151223_app.log)
        'enableDatePrefix' => true,
        'maxFileSize' => 1024 * 1,
        'maxLogFiles' => 100,
      ],
      /**
       * trace 级别日志：记录关于某段代码运行的相关消息。主要是用于开发环境。
       * 使用方法：Yii::trace()
       */
      [
        'class' => 'common\components\FileTarget',
        // 日志等级
        'levels' => ['trace'],
        // 被收集记录的额外数据
        'logVars' => ['_GET', '_POST', '_FILES', '_COOKIE', '_SESSION','_SERVER'],
        // 指定日志保存的文件名
        'logFile' => '@app/runtime/logs/trace/app.log',
        // 是否开启日志 (@app/runtime/logs/trace/20151223_app.log)
        'enableDatePrefix' => true,
        'maxFileSize' => 1024 * 1,
        'maxLogFiles' => 100,
      ],
    ],
  ],
],

Yii::log($message,CLogger::LEVEL_ERROR,$category);

/**
 * Initializes this application component.
 * This method is required by the IApplicationComponent interface.  
*/
 public function init(){ 
  parent::init(); 
  foreach($this->_routes as $name=>$route) { 
    $route=Yii::createComponent($route);  
    $route->init();  
    $this->_routes[$name]=$route; 
  } 
  Yii::getLogger()->attachEventHandler('onFlush',array($this,'collectLogs')); 
  Yii::app()->attachEventHandler('onEndRequest',array($this,'processLogs'));}

 if($this->hasEventHandler('onEndRequest')) {
 $this->onEndRequest(new CEvent($this));
 }

 $logs=$logger->getLogs($this->levels,$this->categories); //执行过滤，只得到期望信息

 CFileLogRoute::processLogs($logs);

'preload'=>array('log'),
components => array(
       'log'=>array(
         'class'=>'CLogRouter',
         'routes'=>array(
          array(
            'class'=>'CFileLogRoute',
            'levels'=>'error, warning,trace',
          ),
         )
        ）
       ）

 if($this->hasEventHandler('onEndRequest')) {
  $this->onEndRequest(new CEvent($this));
 }

'log'=>array(
'class'=>'CLogRouter',
'routes'=>array(
array(
'class'=>'CFileLogRoute',
'levels'=>'error, warning,trace',
),
array(
'class' => 'myEmailLogRoute',
'levels' => 'error', #所有异常的错误级别均为error, 
'categories' => 'exception.CDbException', #数据库产生错误时，均会产生CDbException异常。
'host' => 'mail.163.com',
'port' => 25,
'user' => 'jeff_yu',
'password' => 'you password',
'timeout' => 30,
'emails' => 'jeff_yu@gmail.com', #日志接收人。
'sentFrom' => 'jeff_yu@gmail.com',
),