组件（component），是Yii框架的基类，实现了属性、事件、行为三类功能，如果需要事件和行为的功能，需要继承该类，不需要可直接继承Object类；
1 namespace yii\base;
2
3 use Yii;
4
5 /**
6 * Component is the base class that implements the *property*, *event* and *behavior* features.
7 * 组件，是Yii框架的基类，实现了属性、事件、行为三类功能
8 * Component provides the *event* and *behavior* features, in addition to the *property* feature which is implemented in
9 * its parent class [[Object]].
10 * 组件提供了事件和行为功能，通过附加到父类[[Object]]的属性功能中
11 * Event is a way to "inject" custom code into existing code at certain places. For example, a comment object can trigger
12 * an "add" event when the user adds a comment. We can write custom code and attach it to this event so that when the event
13 * is triggered (i.e. comment will be added), our custom code will be executed.
14 * 事件，可以在特定的时点，触发执行预先设定的一段代码，例如一个评论对象能够在用户添加评论的时候触发一个add事件，我们能够自定义一些代码添加到
15 * 这个事件中，在添加评论的时候会触发事件，执行自定义的代码
16 * An event is identified by a name that should be unique within the class it is defined at. Event names are *case-sensitive*.
17 * 事件的名称在类中是唯一的，区分大小写
18 * One or multiple PHP callbacks, called *event handlers*, can be attached to an event. You can call [[trigger()]] to
19 raise an event. When an event is raised, the event handlers will be invoked automatically in the order they were
20 attached.
21 * 一个或者多个事件处理程序嫩巩固被添加到一个事件，能够通过调用[[trigger()]]触发事件，事件处理程序将会按照添加的先后顺序依次执行
22 * To attach an event handler to an event, call [[on()]]:
23 * 添加事件是通过on()方法添加
24 * ```php
25 * $post->on(‘update‘, function ($event) { //给update方法添加一个匿名函数的时间，该事件的作用是发送邮件信息
26 * // send email notification
27 * });
28 * ```
29 *
30 * In the above, an anonymous function is attached to the "update" event of the post. You may attach
31 * the following types of event handlers:
32 * 事件处理程序有以下几种形式
33 * - anonymous function: `function ($event) { ... }`匿名函数
34 * - object method: `[$object, ‘handleAdd‘]` 对象的方法 以数组的方式传入
35 * - static class method: `[‘Page‘, ‘handleAdd‘]` 静态方法 以数组的方式传入
36 * - global function: `‘handleAdd‘` 全局函数 不带参数和括号，只有函数名
37 *
38 * The signature of an event handler should be like the following:
39 *
40 * ```php
41 * function foo($event) 事件处理程序的格式
42 * ```
43 *
44 * where `$event` is an [[Event]] object which includes parameters associated with the event.
45 *
46 * You can also attach a handler to an event when configuring a component with a configuration array.
47 * The syntax is like the following:
48 * 可以通过配置文件来配置事件，格式如下
49 * ```php
50 * [
51 * ‘on add‘ => function ($event) { ... } 给add 添加一个事件
52 * ]
53 * ```
54 *
55 * where `on add` stands for attaching an event to the `add` event.
56 *
57 * Sometimes, you may want to associate extra data with an event handler when you attach it to an event
58 * and then access it when the handler is invoked. You may do so by
59 * on()方法的第三个参数可以给事件处理程序传入参数
60 * ```php
61 * $post->on(‘update‘, function ($event) {
62 * // the data can be accessed via $event->data
63 * }, $data);
64 * ```
65 *
66 * A behavior is an instance of [[Behavior]] or its child class. A component can be attached with one or multiple
67 * behaviors. When a behavior is attached to a component, its public properties and methods can be accessed via the
68 * component directly, as if the component owns those properties and methods.
69 * 行为可以在不修改现有类的情况下，对类的功能进行扩充。 通过将行为绑定到一个类，可以使类具有行为本身所定义的属性和方法，
70 * 就好像类本来就有这些属性和方法一样。 而且不需要写一个新的类去继承或包含现有类。
71 * To attach a behavior to a component, declare it in [[behaviors()]], or explicitly call [[attachBehavior]]. Behaviors
72 * declared in [[behaviors()]] are automatically attached to the corresponding component.
73 *
74 * One can also attach a behavior to a component when configuring it with a configuration array. The syntax is like the
75 * following:
76 * 配置行为的数组格式
77 * ```php
78 * [
79 * ‘as tree‘ => [
80 * ‘class‘ => ‘Tree‘,
81 * ],
82 * ]
83 * ```
84 *
85 * where `as tree` stands for attaching a behavior named `tree`, and the array will be passed to [[\Yii::createObject()]]
86 * to create the behavior object.
87 *
88 * @property Behavior[] $behaviors List of behaviors attached to this component. This property is read-only.
89 *
90 * @author Qiang Xue <[email protected]>
91 * @since 2.0
92 */
93 class Component extends Object
94 {
95 /**
96 * @var array 当前对象的已绑定的事件数组 (事件名 => 处理程序)
97 */
98 private $_events = [];
99 /**
100 * @var Behavior[]|null 当前对象的已绑定的行为数组 (行为名 => 行为类). 初始化之前为空.
101 */
102 private $_behaviors;
103
104
105 /**
106 * Returns the value of a component property.
107 * This method will check in the following order and act accordingly:
108 *
109 * - a property defined by a getter: return the getter result
110 * - a property of a behavior: return the behavior property value
111 *
112 * 重写 Object 中的 getter 方法，添加对 behaviors 的处理
113 * 如果当前组件的属性中没有该属性，则遍历 behaviors，如果其中有相应的属性，返回behaviors中的属性
114 *
115 * Do not call this method directly as it is a PHP magic method that
116 * will be implicitly called when executing `$value = $component->property;`.
117 * @param string $name 属性名
118 * @return mixed 属性值或者行为中的属性值
119 * @throws 属性未定义
120 * @throws 属性只读
121 * @see __set()
122 */
123 public function __get($name)
124 {
125 $getter = ‘get‘ . $name;
126 if (method_exists($this, $getter)) {
127 // 构造getter方法，如果getter方法存在的话，调用getter方法，返回属性值
128 return $this->$getter();
129 } else {
130 // behavior property
131 $this->ensureBehaviors();//调用该方法确保行为已绑定
132 foreach ($this->_behaviors as $behavior) {
133 if ($behavior->canGetProperty($name)) {
134 //调用父类的方法，判断检查对象或类是否能够获取 $name 属性，如果第二个参数为 true（默认是true），则不局限于是否有 getter
135 // 如果 behavior 中含有该属性，就返回 behavior 中的这个属性
136 return $behavior->$name;
137 }
138 }
139 }
140 if (method_exists($this, ‘set‘ . $name)) {//跟父类相同，判断属性是否只写
141 throw new InvalidCallException(‘Getting write-only property: ‘ . get_class($this) . ‘::‘ . $name);
142 } else {//抛出异常
143 throw new UnknownPropertyException(‘Getting unknown property: ‘ . get_class($this) . ‘::‘ . $name);
144 }
145 }
146
147 /**
148 * Sets the value of a component property.
149 * This method will check in the following order and act accordingly:
150 *
151 * - a property defined by a setter: set the property value
152 * - an event in the format of "on xyz": attach the handler to the event "xyz"
153 * - a behavior in the format of "as xyz": attach the behavior named as "xyz"
154 * - a property of a behavior: set the behavior property value
155 **
156 * 重写 Object 中的 setter 方法
157 * 如果 $name 是 ‘on xyz‘，就会将 xyz 事件添加到该对象中
158 * 如果 $name 是 ‘as xyz‘，就会将 xyz 行为添加到该对象中
159 * 添加对 behaviors 的处理，循环 behaviors，如果其中有相应的属性，就设置它
160 *
161 * Do not call this method directly as it is a PHP magic method that
162 * will be implicitly called when executing `$component->property = $value;`.
163 * @param string $name 属性名或者事件名
164 * @param mixed $value the 属性值
165 * @throws UnknownPropertyException if the property is not defined
166 * @throws InvalidCallException if the property is read-only.
167 * @see __get()
168 */
169 public function __set($name, $value)
170 {
171 $setter = ‘set‘ . $name;//在属性名前面加set构建setter方法
172 if (method_exists($this, $setter)) {//如果setter方法存在
173 // 调用该方法设置属性值
174 $this->$setter($value);
175
176 return;
177 } elseif (strncmp($name, ‘on ‘, 3) === 0) {//如果方法不存在，且$name以on+空格开始
178 // on event: attach event handler
179 $this->on(trim(substr($name, 3)), $value);//调用on方法将事件处理程序附加到事件
180
181 return;
182 } elseif (strncmp($name, ‘as ‘, 3) === 0) {//否则，如果$name以as+空格开始
183 // as behavior: attach behavior
184 $name = trim(substr($name, 3));//截取as后面的字符
185 $this->attachBehavior($name, $value instanceof Behavior ? $value : Yii::createObject($value));//用attachBehavior添加一个行为到组件
186
187 return;
188 } else {//否则
189 // behavior property
190 $this->ensureBehaviors();
191 foreach ($this->_behaviors as $behavior) {
192 if ($behavior->canSetProperty($name)) {//遍历行为（behaviors），如果行为中有可以设置的属性
193 $behavior->$name = $value;//给该行为类中的属性设置属性值
194
195 return;
196 }
197 }
198 }
199 if (method_exists($this, ‘get‘ . $name)) {//如果该属性的get方法存在，表名该方法只读，抛出异常
200 throw new InvalidCallException(‘Setting read-only property: ‘ . get_class($this) . ‘::‘ . $name);
201 } else {//否则抛出异常，未知的属性
202 throw new UnknownPropertyException(‘Setting unknown property: ‘ . get_class($this) . ‘::‘ . $name);
203 }
204 }
205
206 /**
207 * Checks if a property is set, i.e. defined and not null.
208 * This method will check in the following order and act accordingly:
209 *
210 * - a property defined by a setter: return whether the property is set
211 * - a property of a behavior: return whether the property is set
212 * - return `false` for non existing properties
213 *
214 * 重写 Object 中的 isset 方法，添加对 behaviors 的处理，
215 * 如果component中不存在该属性，遍历 behaviors，如果其中有相应的属性，就认为有
216 *
217 * Do not call this method directly as it is a PHP magic method that
218 * will be implicitly called when executing `isset($component->property)`.
219 * @param string $name 属性名或事件名
220 * @return boolean whether the named property is set
221 * @see http://php.net/manual/en/function.isset.php
222 */
223 public function __isset($name)
224 {
225 $getter = ‘get‘ . $name;
226 if (method_exists($this, $getter)) {
227 // 判断是否有getter方法，且是否有返回值，有 getter 方法且获取的值不为 null，才认为该属性存在
228 return $this->$getter() !== null;
229 } else {
230 // behavior property
231 $this->ensureBehaviors();//确定行为已经绑定
232 foreach ($this->_behaviors as $behavior) {//遍历 behaviors
233 if ($behavior->canGetProperty($name)) {//如果行为（behaviors）中有相应的属性，就认为有
234 return $behavior->$name !== null;
235 }
236 }
237 }
238 return false;
239 }
240
241 /**
242 * Sets a component property to be null.
243 * This method will check in the following order and act accordingly:
244 *
245 * - a property defined by a setter: set the property value to be null
246 * - a property of a behavior: set the property value to be null
247 *
248 * 重写 Object 中的 unset 方法，添加对 behaviors 的处理
249 * 如果component中不存在该属性，遍历 behaviors，如果其中有相应的属性，设置为空
250 *
251 * Do not call this method directly as it is a PHP magic method that
252 * will be implicitly called when executing `unset($component->property)`.
253 * @param string $name 属性名
254 * @throws InvalidCallException if the property is read only.
255 * @see http://php.net/manual/en/function.unset.php
256 */
257 public function __unset($name)
258 {
259 $setter = ‘set‘ . $name;
260 if (method_exists($this, $setter)) {
261 // 如果setter方法存在，通过 setter 方法，将它设置为 null
262 $this->$setter(null);
263 return;
264 } else {
265 // behavior property
266 $this->ensureBehaviors();
267 foreach ($this->_behaviors as $behavior) {//否则遍历 behaviors
268 if ($behavior->canSetProperty($name)) {//如果行为中有相应的属性，设置为空
269 $behavior->$name = null;
270 return;
271 }
272 }
273 }
274 //抛出异常
275 throw new InvalidCallException(‘Unsetting an unknown or read-only property: ‘ . get_class($this) . ‘::‘ . $name);
276 }
277
278 /**
279 * Calls the named method which is not a class method.
280 *
281 * This method will check if any attached behavior has
282 * the named method and will execute it if available.
283 *
284 * 重写 Object 中的 call 方法，添加对 behaviors 的处理
285 * 遍历 behaviors，如果其中有相应方法，就执行该 behavior 的方法
286 *
287 * Do not call this method directly as it is a PHP magic method that
288 * will be implicitly called when an unknown method is being invoked.
289 * @param string $name 方法名
290 * @param array $params 参数
291 * @return mixed 方法执行后的返回值
292 * @throws UnknownMethodException when calling unknown method
293 */
294 public function __call($name, $params)
295 {
296 $this->ensureBehaviors();//确认行为已经绑定
297 foreach ($this->_behaviors as $object) {
298 if ($object->hasMethod($name)) {//调用父类的方法，判断该行为中是否有$name方法
299 return call_user_func_array([$object, $name], $params);//如果行为中有该方法，则执行该方法
300 }
301 }
302 throw new UnknownMethodException(‘Calling unknown method: ‘ . get_class($this) . "::$name()");
303 }
304
305 /**
306 * This method is called after the object is created by cloning an existing one.
307 * It removes all behaviors because they are attached to the old object.
308 *
309 * 在对象克隆clone的时候调用这个方法，将其 _events 和 _behaviors 设置为空
310 * 当对象被复制后，PHP 5 会对对象的所有属性执行一个浅复制（shallow copy）。
311 * 所有的引用属性 仍然会是一个指向原来的变量的引用，所以没必要浪费内存
312 *
313 */
314 public function __clone()
315 {
316 // 对象复制时，将它的 _events 设置为空数组，将 _behaviors 设置为 null
317 $this->_events = [];
318 $this->_behaviors = null;
319 }
320
321 /**
322 * Returns a value indicating whether a property is defined for this component.
323 * A property is defined if:
324 *
325 * - the class has a getter or setter method associated with the specified name
326 * (in this case, property name is case-insensitive);
327 * - the class has a member variable with the specified name (when `$checkVars` is true);
328 * - an attached behavior has a property of the given name (when `$checkBehaviors` is true).
329 *
330 * 与 Object 中的方法类似，只是添加了是否检测 behavior 的参数
331 *
332 * @param string $name the property name
333 * @param boolean $checkVars whether to treat member variables as properties
334 * @param boolean $checkBehaviors whether to treat behaviors‘ properties as properties of this component
335 * @return boolean whether the property is defined
336 * @see canGetProperty()
337 * @see canSetProperty()
338 */
339 public function hasProperty($name, $checkVars = true, $checkBehaviors = true)
340 {
341 // $checkVars 参数，用来设置是否局限于是否有 getter/setter
342 //$checkBehaviors参数，用来设置是否检测behavior
343 return $this->canGetProperty($name, $checkVars, $checkBehaviors) || $this->canSetProperty($name, false, $checkBehaviors);
344 }
345
346 /**
347 * Returns a value indicating whether a property can be read.
348 * A property can be read if:
349 *
350 * - the class has a getter method associated with the specified name
351 * (in this case, property name is case-insensitive);
352 * - the class has a member variable with the specified name (when `$checkVars` is true);
353 * - an attached behavior has a readable property of the given name (when `$checkBehaviors` is true).
354 *
355 * 检查对象或类是否能够获取 $name 属性，增加了对behavior的检查
356 *
357 * @param string $name the property name
358 * @param boolean $checkVars whether to treat member variables as properties
359 * @param boolean $checkBehaviors whether to treat behaviors‘ properties as properties of this component
360 * @return boolean whether the property can be read
361 * @see canSetProperty()
362 */
363 public function canGetProperty($name, $checkVars = true, $checkBehaviors = true)
364 { // $checkVars 参数，用来设置是否局限于是否有 getter/setter
365 if (method_exists($this, ‘get‘ . $name) || $checkVars && property_exists($this, $name)) {
366 return true;
367 } elseif ($checkBehaviors) {
368 //$checkBehaviors参数，用来设置是否检测behavior
369 $this->ensureBehaviors();
370 foreach ($this->_behaviors as $behavior) {
371 if ($behavior->canGetProperty($name, $checkVars)) {
372 return true;
373 }
374 }
375 }
376 return false;
377 }
378
379 /**
380 * Returns a value indicating whether a property can be set.
381 * A property can be written if:
382 *
383 * - the class has a setter method associated with the specified name
384 * (in this case, property name is case-insensitive);
385 * - the class has a member variable with the specified name (when `$checkVars` is true);
386 * - an attached behavior has a writable property of the given name (when `$checkBehaviors` is true).
387 *
388 * 检查对象或类是否能够设置 $name 属性，增加了对behavior的检查
389 *
390 * @param string $name the property name
391 * @param boolean $checkVars whether to treat member variables as properties
392 * @param boolean $checkBehaviors whether to treat behaviors‘ properties as properties of this component
393 * @return boolean whether the property can be written
394 * @see canGetProperty()
395 */
396 public function canSetProperty($name, $checkVars = true, $checkBehaviors = true)
397 {
398 // $checkVars 参数，用来设置是否局限于是否有 getter/setter
399 if (method_exists($this, ‘set‘ . $name) || $checkVars && property_exists($this, $name)) {
400 return true;
401 } elseif ($checkBehaviors) {//$checkBehaviors参数，用来设置是否检测behavior
402 $this->ensureBehaviors();
403 foreach ($this->_behaviors as $behavior) {
404 if ($behavior->canSetProperty($name, $checkVars)) {//调用父类方法判断
405 return true;
406 }
407 }
408 }
409 return false;
410 }
时间： 2024-10-07 21:36:26