View中渲染view视图文件的前置和后置方法，以及渲染动态内容的方法：
1 /**
2 * @return string|boolean the view file currently being rendered. False if no view file is being rendered.
3 */
4 public function getViewFile()
5 {
6 return end($this->_viewFiles);//返回[_viewFiles]中的最后一个view文件，即默认被渲染的文件
7 }
8
9 /**
10 * This method is invoked right before [[renderFile()]] renders a view file.
11 * Render的前置事件，在执行[renderFile()]方法时被调用，默认触发[[EVENT_BEFORE_RENDER]]事件
12 * The default implementation will trigger the [[EVENT_BEFORE_RENDER]] event.
13 * If you override this method, make sure you call the parent implementation first.
14 * 如果要重写该方法，要确保首先调用父类的同名方法
15 * @param string $viewFile the view file to be rendered.
16 * @param array $params the parameter array passed to the [[render()]] method.
17 * @return boolean whether to continue rendering the view file.
18 */
19 public function beforeRender($viewFile, $params)
20 {
21 //实例化ViewEvent
22 $event = new ViewEvent([
23 ‘viewFile‘ => $viewFile,
24 ‘params‘ => $params,
25 ]);
26 //触发[EVENT_BEFORE_RENDER]事件
27 $this->trigger(self::EVENT_BEFORE_RENDER, $event);
28
29 return $event->isValid;//返回值可以判断是否继续渲染文件
30 }
31
32 /**
33 * This method is invoked right after [[renderFile()]] renders a view file.
34 * Render的后置事件，在执行[renderFile()]方法后被调用，默认触发[[EVENT_AFTER_RENDER]]事件
35 * The default implementation will trigger the [[EVENT_AFTER_RENDER]] event.
36 * If you override this method, make sure you call the parent implementation first.
37 * 如果要重写该方法，要确保首先调用父类的同名方法
38 * @param string $viewFile the view file being rendered.
39 * @param array $params the parameter array passed to the [[render()]] method.
40 * @param string $output the rendering result of the view file. Updates to this parameter
41 * will be passed back and returned by [[renderFile()]].
42 */
43 public function afterRender($viewFile, $params, &$output)
44 {
45 if ($this->hasEventHandlers(self::EVENT_AFTER_RENDER)) {//判断[EVENT_AFTER_RENDER]事件是否有处理函数
46 //实例化ViewEvent
47 $event = new ViewEvent([
48 ‘viewFile‘ => $viewFile,
49 ‘params‘ => $params,
50 ‘output‘ => $output,
51 ]);
52 //触发[EVENT_AFTER_RENDER]事件
53 $this->trigger(self::EVENT_AFTER_RENDER, $event);
54 $output = $event->output;//执行后置事件后的输出结果
55 }
56 }
57
58 /**
59 * Renders a view file as a PHP script.
60 * 将一个view文件当作PHP脚本渲染
61 * This method treats the view file as a PHP script and includes the file.
62 * It extracts the given parameters and makes them available in the view file.
63 * The method captures the output of the included view file and returns it as a string.
64 * 将传入的参数转换为变量，包含并执行view文件，返回执行结果
65 * This method should mainly be called by view renderer or [[renderFile()]].
66 *
67 * @param string $_file_ the view file.
68 * @param array $_params_ the parameters (name-value pairs) that will be extracted and made available in the view file.
69 * @return string the rendering result
70 */
71 public function renderPhpFile($_file_, $_params_ = [])
72 {
73 //ob_start() — 打开输出控制缓冲
74 ob_start();
75 // ob_implicit_flush () — 默认为关闭缓冲区，打开绝对输出后，每个脚本输出都直接发送到浏览器，不再需要调用 flush()
76 ob_implicit_flush(false);
77 extract($_params_, EXTR_OVERWRITE);//extract() - 用于将一个数组转换为变量使用，键名为变量名，键值为对应的变量值
78 require($_file_);
79 //ob_get_clean() — 得到当前缓冲区的内容并删除当前输出缓
80 return ob_get_clean();
81 }
82
83 /**
84 * Renders dynamic content returned by the given PHP statements.
85 * 渲染动态内容
86 * This method is mainly used together with content caching (fragment caching and page caching)
87 * 该方法主要用来聚合缓存的内容（片段缓存和页面缓存）
88 * when some portions of the content (called *dynamic content*) should not be cached.
89 * The dynamic content must be returned by some PHP statements.
90 * 用来渲染某些被PHP语句返回的动态内容
91 * @param string $statements the PHP statements for generating the dynamic content.
92 * @return string the placeholder of the dynamic content, or the dynamic content if there is no
93 * active content cache currently.
94 */
95 public function renderDynamic($statements)
96 {
97 if (!empty($this->cacheStack)) {//动态内容的栈列表不为空
98 $n = count($this->dynamicPlaceholders);//计算动态内容条数
99 $placeholder = "<![CDATA[YII-DYNAMIC-$n]]>";//生成占位符--动态内容前缀--起标记作用
100 $this->addDynamicPlaceholder($placeholder, $statements);//添加动态内容占位符
101
102 return $placeholder;
103 } else {
104 return $this->evaluateDynamicContent($statements);//动态内容的栈列表为空，值行传入的PHP语句，返回执行结果
105 }
106 }
107
108 /**
109 * Adds a placeholder for dynamic content.
110 * 给dynamic content添加一个占位符
111 * This method is internally used.
112 * 该方法是内部使用的
113 * @param string $placeholder the placeholder name
114 * @param string $statements the PHP statements for generating the dynamic content
115 */
116 public function addDynamicPlaceholder($placeholder, $statements)
117 {
118 foreach ($this->cacheStack as $cache) {
119 $cache->dynamicPlaceholders[$placeholder] = $statements;//给widget中的[FragmentCache]添加占位符
120 }
121 $this->dynamicPlaceholders[$placeholder] = $statements;//给当前视图添加动态内容占位符
122 }
123
124 /**
125 * Evaluates the given PHP statements.
126 * 求给定的PHP语句的值
127 * This method is mainly used internally to implement dynamic content feature.
128 * 该方法是内部使用实现动态内容功能
129 * @param string $statements the PHP statements to be evaluated.
130 * @return mixed the return value of the PHP statements.
131 */
132 public function evaluateDynamicContent($statements)
133 {
134 return eval($statements);//eval() 函数用于执行文本方式输入的php语句
135 }
GitHub地址： https://github.com/mogambos/yii-2.0.7/blob/master/vendor/yiisoft/yii2/base/View.php
时间： 2024-10-13 02:39:36