yii2源码学习笔记(五）
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Event是所有事件类的基类。它封装了与事件相关的参数。
yii2\base\Event.php
1 <?php 2 /** 3 * @link http://www.yiiframework.com/ 4 * @copyright Copyright (c) 2008 Yii Software LLC 5 * @license http://www.yiiframework.com/license/ 6 */ 7 8 namespace yii\base; 9 10 /** 11 * Event is the base class for all event classes. 12 * 13 * It encapsulates the parameters associated with an event. 14 * The [[sender]] property describes who raises the event. 15 * And the [[handled]] property indicates if the event is handled. 16 * If an event handler sets [[handled]] to be true, the rest of the 17 * uninvoked handlers will no longer be called to handle the event. 18 * Event是所有事件类的基类。 它封装了与事件相关的参数。 sender属性指的是谁发起来的事件。 19 * handled属性指的是事件的处理方式. 如果一个事件处理程序设置了handled为true，其它未处理的事件处理程序将不会被调用。 20 * Additionally, when attaching an event handler, extra data may be passed 21 * and be available via the [[data]] property when the event handler is invoked. 22 * 当附加事件处理程序时，可能会通过额外的数据 ，当事件处理程序被调用时，可通过[ data]属性提供。 23 * @author Qiang Xue <[email protected]> 24 * @since 2.0 25 */ 26 class Event extends Object 27 { 28 /** 29 * 事件的名字,通过[[Component::trigger()]] 和 [[trigger()]]方法设置，事件处理程序可以使用此属性来检查它的处理事件。 30 * @var string the event name. This property is set by [[Component::trigger()]] and [[trigger()]]. 31 * Event handlers may use this property to check what event it is handling. 32 */ 33 public $name; 34 /** 35 * 触发事件的对象，如果未设置，则设置为调用"trigger()"方法的对象，如果是在静态环境下触发的类级别的事件，属性为空 36 * @var object the sender of this event. If not set, this property will be 37 * set as the object whose "trigger()" method is called. 38 * This property may also be a `null` when this event is a 39 * class-level event which is triggered in a static context. 40 */ 41 public $sender; 42 /** 43 * 如果一个事件处理程序设置了handled为true，其它未处理的事件处理程序将不会被执行。 44 * @var boolean whether the event is handled. Defaults to false. 45 * When a handler sets this to be true, the event processing will stop and 46 * ignore the rest of the uninvoked event handlers. 47 */ 48 public $handled = false; 49 /** 50 * 附加一个事件处理程序时通过[[Component::on()]]传入data，且对应当前执行的事件处理程序 51 * @var mixed the data that is passed to [[Component::on()]] when attaching an event handler. 52 * Note that this varies according to which event handler is currently executing. 53 */ 54 public $data; 55 /** 56 *存储所有的 event，所有的 event 对象/类都共用这一数据 57 * @var array 58 */ 59 private static $_events = []; 60 61 62 /** 63 * Attaches an event handler to a class-level event. 64 * 为一个类添加事件 65 * When a class-level event is triggered, event handlers attached 66 * to that class and all parent classes will be invoked. 67 * 当一个类级别事件触发，将调用该类和所有父类的事件处理程序。 68 * For example, the following code attaches an event handler to `ActiveRecord`‘s 69 * `afterInsert` event: 70 * 71 * ~~~ 72 * Event::on(ActiveRecord::className(), ActiveRecord::EVENT_AFTER_INSERT, function ($event) { 73 * Yii::trace(get_class($event->sender) . ‘ is inserted.‘); 74 * }); 75 * ~~~ 76 * 77 * The handler will be invoked for EVERY successful ActiveRecord insertion. 78 * 该处理程序是将每一个成功的[[ActiveRecord]]插入调用。 79 * For more details about how to declare an event handler, please refer to [[Component::on()]]. 80 * 81 * @param string $class the fully qualified class name to which the event handler needs to attach. 82 * 定义的类级别的对象或者类名称. 83 * @param string $name the event name. 事件名 84 * @param callable $handler the event handler. 事件处理程序 85 * @param mixed $data the data to be passed to the event handler when the event is triggered. 86 * When the event handler is invoked, this data can be accessed via [[Event::data]]. 87 * 当事件被触发时，将传递给事件处理程序的数据。当调用事件处理程序时，该数据可以通过[[Event::data]]传递 88 * @param boolean $append whether to append new event handler to the end of the existing 89 * handler list. If false, the new handler will be inserted at the beginning of the existing 90 * handler list.是否将新事件处理程序附加到现有的处理程序列表的结尾。如果false，新的处理程序将被插入到现有的处理程序列表开头 91 * @see off() 92 */ 93 public static function on($class, $name, $handler, $data = null, $append = true) 94 { 95 // 去掉 class 最左边的反斜杠 96 $class = ltrim($class, ‘\\‘); 97 if ($append || empty(self::$_events[$name][$class])) { 98 //如果 append 为true，附加到$_events中名字为 $name 的数组结尾。如果false，被插入列表开头 99 self::$_events[$name][$class][] = [$handler, $data]; 100 } else { 101 array_unshift(self::$_events[$name][$class], [$handler, $data]); 102 } 103 } 104 105 /** 106 * Detaches an event handler from a class-level event. 107 * 108 * This method is the opposite of [[on()]]. 109 * [[on()]]的反方法，移除一个类的事件 110 * @param string $class the fully qualified class name from which the event handler needs to be detached. 111 * 定义类级别的对象或者类名称. 112 * @param string $name the event name. 事件名 113 * @param callable $handler the event handler to be removed. 事件处理程序 114 * If it is null, all handlers attached to the named event will be removed. 如果是null，移除所有相关事件 115 * @return boolean whether a handler is found and detached. 一个处理程序是否被发现且分离。 116 * @see on() 117 */ 118 public static function off($class, $name, $handler = null) 119 { 120 // 去掉最左边的反斜线 121 $class = ltrim($class, ‘\\‘); 122 if (empty(self::$_events[$name][$class])) { 123 return false; // 该事件不存在，返回false 124 } 125 if ($handler === null) { 126 // 如果 $handler 为空，该类下该所有是这个名字的事件移除， 127 unset(self::$_events[$name][$class]); 128 return true;//移除标记 129 } else { 130 $removed = false;//移除标记 131 foreach (self::$_events[$name][$class] as $i => $event) { 132 // 如果 $handler 不为空，循环 $_events 找到相应的 $handler，只移除这个 $handler 和 data 组成的数组 133 if ($event[0] === $handler) { 134 unset(self::$_events[$name][$class][$i]); 135 $removed = true;//移除标记 136 } 137 } 138 if ($removed) {// 移除成功，使数组重新变成一个自然数组 139 self::$_events[$name][$class] = array_values(self::$_events[$name][$class]); 140 } 141 142 return $removed; 143 } 144 } 145 146 /** 147 * Returns a value indicating whether there is any handler attached to the specified class-level event. 148 * Note that this method will also check all parent classes to see if there is any handler attached 149 * to the named event.检测在某个类或者对象是否具有某个事件 同时检测父类 150 * @param string|object $class the object or the fully qualified class name specifying the class-level event. 151 * 定义类级别的对象或者类名称. 152 * @param string $name the event name. 事件名 153 * @return boolean whether there is any handler attached to the event. 是否有处理程序连接到事件 154 */ 155 public static function hasHandlers($class, $name) 156 { 157 if (empty(self::$_events[$name])) { 158 return false; //如果不存在事件，返回false 159 } 160 if (is_object($class)) { 161 //如果是对象，获取类名 162 $class = get_class($class); 163 } else { 164 //如果是类名，去掉左边的反斜杠 165 $class = ltrim($class, ‘\\‘); 166 } 167 do {// 如果类中找不到，就去父类中找，直到找到或者没有父类了为止，返回true 168 if (!empty(self::$_events[$name][$class])) { 169 return true; 170 } 171 } while (($class = get_parent_class($class)) !== false); 172 173 return false; 174 } 175 176 /** 177 * Triggers a class-level event. 触发类级别事件。 178 * This method will cause invocation of event handlers that are attached to the named event 179 * for the specified class and all its parent classes.该方法将调用指定类中的事件处理程序 180 * @param string|object $class the object or the fully qualified class name specifying the class-level event. 181 * 定义的类级别的对象或者类名称. 182 * @param string $name the event name. 事件名 183 * @param Event $event the event parameter. If not set, a default [[Event]] object will be created. 184 * 事件参数，未设置则默认创建 185 */ 186 public static function trigger($class, $name, $event = null) 187 { 188 if (empty(self::$_events[$name])) { 189 return;//如果事件为空，直接返回 190 } 191 if ($event === null) { 192 // 事件不存在，就创建一个静态 Event 对象 193 $event = new static; 194 } 195 $event->handled = false;//事件是否被处理标志，默认未处理 196 $event->name = $name;//事件名 197 198 if (is_object($class)) { 199 if ($event->sender === null) { 200 // 如果 $class 是个对象，并且sender为空，就将 $class赋给sender，即$class发起事件 201 $event->sender = $class; 202 } 203 $class = get_class($class);//获取类名 204 } else { 205 $class = ltrim($class, ‘\\‘);//不是对象，去掉左边的反斜线 206 } 207 do {// 循环类的 $_event，直到遇到 $event->handled 为真或者没有父类了为止 208 if (!empty(self::$_events[$name][$class])) {//找到符合条件的类 209 foreach (self::$_events[$name][$class] as $handler) { 210 // 将参数赋到 event 对象的 data 属性上 211 $event->data = $handler[1]; 212 // 调用 $handler 方法 213 call_user_func($handler[0], $event); 214 if ($event->handled) { 215 // 事件处理程序handled为true，其它未处理的事件处理程序将不会被调用。 216 return; 217 } 218 } 219 } 220 } while (($class = get_parent_class($class)) !== false); 221 } 222 }
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