Yii framework analysis (2) - CComponent class analysis

Yii is a component-based web framework, and the CComponent class is the base class for all components.

The CComponent class provides subclasses with programming interfaces based on properties, events, and behaviors.

1. Component properties (property)

The Ccomponent class does not provide variable storage of properties, and subclasses need to provide two methods to achieve this. The getPropertyName() method of the subclass provides the value operation data of $component->PropertyName, and the setPropertyName($val) method of the subclass provides the value assignment operation of $component->PropertyName.

$width=$component->textWidth;???? // Get the textWidth attribute

The implementation is to call the method provided by the subclass $width=$component->getTextWidth( )

$component->textWidth=$width;???? // Set the textWidth attribute

The implementation is to call the method provided by the subclass $component->setTextWidth($width )

public function getTextWidth()
{
    return $this->_textWidth;
}
 
public function setTextWidth($value)
{
    $this->_textWidth=$value;
}

The attribute values ​​of the component are case-insensitive (members of the class are case-sensitive)

2. Component events (events)

Component events It is a special attribute that can register (bind) an event handler (which can be a function name, class method or object method) to an event name, and the handler will be automatically called when the event is evoked.
Component events are stored in the $_e[] array of CComponent. The key value of the array is the name of the event, and the value of the key value is a Clist object. Clist is a queue container provided by Yii. The method add() of Clist adds The callback handle of the event.

//Add a global function to event processing
$component-> onBeginRequest="logRequest";
//Add a class static method to event processing
$component-> onBeginRequest=array("CLog"," logRequest");
//Add an object method to event processing
$component-> onBeginRequest=array($mylog," logRequest");

Raise events:
$component ->raiseEvent('onBeginRequest ', $event);
will automatically call:
logRequest($event), Clog::logRequest($event) and $mylog. logRequest($event)

The event handler must be defined as follows:

function methodName($event)
{
……
}
$event Parameters It is an instance of CEvent or its subclass, which at least contains the information of "who hung up this event".

The name of the event starts with "on", which can be used to distinguish attributes and events in __get() and __set().

3. Component behavior (behavior)

The behavior of a component is a method of extending component functionality without inheritance (see the strategy pattern in design patterns).

Behavior classes must implement the IBehavior interface, and most behaviors can be extended from the CBehavior base class.

IBehavior interface provides 4 methods.
attach($component) associates itself to the component, detach($component) removes the $component association, getEnabled() and setEnabled() set the validity of the behavior object.

The behavior object is stored in the $_m[] array of the component. The array key value is the behavior name string, and the array value is the behavior class object.

The component extends a behavior through attachBehavior ($name,$behavior):
$component-> attachBehavior ('render',$htmlRender)
Adds a name for $component called render For behavior, $htmlRender needs to be an object that implements the IBehavior interface, or an array:

array( ‘class’=>’path.to.BehaviorClass’,
    ‘property1′=>’value1′,
    ‘property2′=>’value2′,
* )

will create a behavior object and set attribute values ​​based on the class of the array.

$htmlRender is stored in $_m[‘render’].

When an undefined method of a component is called externally, the magic method __call()? will traverse all behavior objects and call it if a method with the same name is found.

For example, $htmlRender has a method renderFromFile(), which can be accessed directly as a component method:

$component-> renderFromFile ()

4.CComponent source code analysis

//所有部件的基类
class CComponent
{
    private $_e;
    private $_m;
 
    //获取部件属性、事件和行为的magic method
    public function __get($name)
    {
        $getter=’get’.$name;
        //是否存在属性的get方法
        if(method_exists($this,$getter))
            return $this->$getter();
        //以on开头，获取事件处理句柄
        else if(strncasecmp($name,’on’,2)===0 && method_exists($this,$name))
        {
            // 事件名小写
            $name=strtolower($name);
            // 如果_e[$name] 不存在，返回一个空的CList事件句柄队列对象
            if(!isset($this->_e[$name]))
                $this->_e[$name]=new CList;
            // 返回_e[$name]里存放的句柄队列对象
            return $this->_e[$name];
        }
        // _m[$name] 里存放着行为对象则返回
        else if(isset($this->_m[$name]))
            return $this->_m[$name];
        else
            throw new CException(Yii::t(‘yii’,'Property “{class}.{property}” is not defined.’,
                array(‘{class}’=>get_class($this), ‘{property}’=>$name)));
    }
 
    /**
    * PHP magic method
    * 设置组件的属性和事件
    */
     public function __set($name,$value)
    {
        $setter=’set’.$name;
        //是否存在属性的set方法
        if(method_exists($this,$setter))
            $this->$setter($value);
        //name以on开头，这是事件处理句柄
        else if(strncasecmp($name,’on’,2)===0 && method_exists($this,$name))
        {
            // 事件名小写
            $name=strtolower($name);
            // _e[$name] 不存在则创建一个CList对象
            if(!isset($this->_e[$name]))
                $this->_e[$name]=new CList;
            // 添加事件处理句柄
            $this->_e[$name]->add($value);
        }
        // 属性没有set方法，只有get方法，为只读属性，抛出异常
        else if(method_exists($this,’get’.$name))
            throw new CException(Yii::t(‘yii’,'Property “{class}.{property}” is read only.’,
                array(‘{class}’=>get_class($this), ‘{property}’=>$name)));
        else
            throw new CException(Yii::t(‘yii’,'Property “{class}.{property}” is not defined.’,
                array(‘{class}’=>get_class($this), ‘{property}’=>$name)));
    }
 
    /**
    * PHP magic method
    * 为isset()函数提供是否存在属性和事件处理句柄的判断
    */
    public function __isset($name)
    {
        $getter=’get’.$name;
        if(method_exists($this,$getter))
            return $this->$getter()!==null;
        else if(strncasecmp($name,’on’,2)===0 && method_exists($this,$name))
        {
            $name=strtolower($name);
            return isset($this->_e[$name]) && $this->_e[$name]->getCount();
        }
        else
            return false;
    }
 
    /**
    * PHP magic method
    * 设置属性值为空或删除事件名字对应的处理句柄
    */
    public function __unset($name)
    {
        $setter=’set’.$name;
        if(method_exists($this,$setter))
            $this->$setter(null);
        else if(strncasecmp($name,’on’,2)===0 && method_exists($this,$name))
            unset($this->_e[strtolower($name)]);
        else if(method_exists($this,’get’.$name))
            throw new CException(Yii::t(‘yii’,'Property “{class}.{property}” is read only.’,
        array(‘{class}’=>get_class($this), ‘{property}’=>$name)));
    }
 
    /**
    * PHP magic method
    *?CComponent未定义的类方法，寻找行为类里的同名方法，实现行为方法的调用
    */
    public function __call($name,$parameters)
    {
        // 行为类存放的$_m数组不空
        if($this->_m!==null)
        {
            // 循环取出$_m数组里存放的行为类
            foreach($this->_m as $object)
            {
                // 行为类对象有效，并且方法存在，调用之
                if($object->enabled && method_exists($object,$name))
                    return call_user_func_array(array($object,$name),$parameters);
            }
        }
        throw new CException(Yii::t(‘yii’,'{class} does not have a method named “{name}”.’,
            array(‘{class}’=>get_class($this), ‘{name}’=>$name)));
    }
 
    /**
    * 根据行为名返回行为类对象
    */
    public function asa($behavior)
    {
        return isset($this->_m[$behavior]) ? $this->_m[$behavior] : null;
    }
 
    /**
    * Attaches a list of behaviors to the component.
    * Each behavior is indexed by its name and should be an instance of
    *?{@link?IBehavior}, a string specifying the behavior class, or an
    * array of the following structure:
    *

* array( *???? ‘class’=>’path.to.BehaviorClass’, *???? ‘property1′=>’value1′, *???? ‘property2′=>’value2′, * ) *

* @param array list of behaviors to be attached to the component * @since 1.0.2 */ public function attachBehaviors($behaviors) { // $behaviors为数组 $name=>$behavior foreach($behaviors as $name=>$behavior) $this->attachBehavior($name,$behavior); } /** * 添加一个行为到组件 */ public function attachBehavior($name,$behavior) { /* $behavior不是IBehavior接口的实例，则为 * array( *???? ‘class’=>’path.to.BehaviorClass’, *???? ‘property1′=>’value1′, *???? ‘property2′=>’value2′, * ) * 传递给Yii::createComponent创建行为了并初始化对象属性 */ if(!($behavior instanceof IBehavior)) $behavior=Yii::createComponent($behavior); $behavior->setEnabled(true); $behavior->attach($this); return $this->_m[$name]=$behavior; } /** * Raises an event. * This method represents the happening of an event. It invokes * all attached handlers for the event. * @param string the event name * @param CEvent the event parameter * @throws CException if the event is undefined or an event handler is invalid. */ public function raiseEvent($name,$event) { $name=strtolower($name); // _e[$name] 事件处理句柄队列存在 if(isset($this->_e[$name])) { // 循环取出事件处理句柄 foreach($this->_e[$name] as $handler) { // 事件处理句柄为全局函数 if(is_string($handler)) call_user_func($handler,$event); else if(is_callable($handler,true)) { // an array: 0 – object, 1 – method name list($object,$method)=$handler; if(is_string($object))?// 静态类方法 call_user_func($handler,$event); else if(method_exists($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 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)))); // $event 的handled 设置为true后停止队列里剩余句柄的调用 if(($event instanceof CEvent) && $event->handled) return; } } else if(YII_DEBUG && !$this->hasEvent($name)) throw new CException(Yii::t(‘yii’,'Event “{class}.{event}” is not defined.’, array(‘{class}’=>get_class($this), ‘{event}’=>$name))); } }

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