View中的查找视图文件方法和渲染文件方法
/**
* Finds the view file based on the given view name.
* 通过view文件名查找view文件
* @param string $view the view name or the path alias of the view file. Please refer to [[render()]]
* on how to specify this parameter.
* @param string $view 视图文件名
* @param object $context the context to be assigned to the view and can later be accessed via [[context]]
* in the view. If the context implements [[ViewContextInterface]], it may also be used to locate
* the view file corresponding to a relative view name.
* @param object $context 情景
* @return string the view file path. Note that the file may not exist.
* @return string view文件路径
* @throws InvalidCallException if a relative view name is given while there is no active context to
* determine the corresponding view file.
*/
protected function findViewFile($view, $context = null)
{
if (strncmp($view, '@', 1) === 0) {//判断$view是否是别名路径
// e.g. "@app/views/main"
$file = Yii::getAlias($view);//调用getAlias()方法获取真实路径
} elseif (strncmp($view, '//', 2) === 0) {//判断$view是否以'//'开始
// e.g. "//layouts/main"
//调用getViewPath()方法在当前模块下查找视图文件目录路径，然后拼接文件名合成视图文件路径
$file = Yii::$app->getViewPath() . DIRECTORY_SEPARATOR . ltrim($view, '/');
} elseif (strncmp($view, '/', 1) === 0) {//判断$view是否以 '/'开始
// e.g. "/site/index"
if (Yii::$app->controller !== null) {//且控制器存在
//则调用getViewPath()查找当前控制器对应的视图文件目录，然后拼接文件名合成视图文件路径
$file = Yii::$app->controller->module->getViewPath() . DIRECTORY_SEPARATOR . ltrim($view, '/');
} else {//否则，抛出异常
throw new InvalidCallException("Unable to locate view file for view '$view': no active controller.");
}
} elseif ($context instanceof ViewContextInterface) {
$file = $context->getViewPath() . DIRECTORY_SEPARATOR . $view;
} elseif (($currentViewFile = $this->getViewFile()) !== false) {
$file = dirname($currentViewFile) . DIRECTORY_SEPARATOR . $view;
} else {
throw new InvalidCallException("Unable to resolve view file for view '$view': no active view context.");
}
if (pathinfo($file, PATHINFO_EXTENSION) !== '') {//如果视图文件的扩展名不为空，直接返回扩展名
return $file;
}
$path = $file . '.' . $this->defaultExtension;//给视图文件添加扩展名
if ($this->defaultExtension !== 'php' && !is_file($path)) {//这里应该是做二次校验，添加扩展名
$path = $file . '.php';
}
return $path;
}
/**
* Renders a view file.
* 渲染一个view文件
*
* If [[theme]] is enabled (not null), it will try to render the themed version of the view file as long
* as it is available.
* 如果[theme]可用（即非空），该方法将视图渲染themed version的视图文件直到[theme]不可用
* The method will call [[FileHelper::localize()]] to localize the view file.
* 该方法将调用[FileHelper::localize()]方法本地化视图文件
*
* If [[renderers|renderer]] is enabled (not null), the method will use it to render the view file.
* Otherwise, it will simply include the view file as a normal PHP file, capture its output and
* return it as a string.
* 如果[renderers|renderer]可用（即非空），该方法将渲染视图文件，否则将把视图文件作为常规的php文件包含进来
* 捕捉它的输出并将其返回为字符串
*
* @param string $viewFile the view file. This can be either an absolute file path or an alias of it.
* @param array $params the parameters (name-value pairs) that will be extracted and made available in the view file.
* @param object $context the context that the view should use for rendering the view. If null,
* existing [[context]] will be used.
* @return string the rendering result
* @throws InvalidParamException if the view file does not exist
*/
public function renderFile($viewFile, $params = [], $context = null)
{
$viewFile = Yii::getAlias($viewFile);//调用getAlias()方法处理输入的视图文件名
if ($this->theme !== null) {
$viewFile = $this->theme->applyTo($viewFile);//如果theme非空，怎将其应用到视图文件
}
if (is_file($viewFile)) {
$viewFile = FileHelper::localize($viewFile);//调用[FileHelper::localize()]方法本地化视图文件
} else {//$viewFile不是文件，抛出异常“视图文件不存在”
throw new InvalidParamException("The view file does not exist: $viewFile");
}
$oldContext = $this->context;
if ($context !== null) {
$this->context = $context;
}
$output = '';
$this->_viewFiles[] = $viewFile;
if ($this->beforeRender($viewFile, $params)) {//如果renderFile的前置事件执行成功
Yii::trace("Rendering view file: $viewFile", __METHOD__);//记录trace信息
$ext = pathinfo($viewFile, PATHINFO_EXTENSION);//获取视图文件扩展名
if (isset($this->renderers[$ext])) {//判断视图文件的扩展名是否支持
if (is_array($this->renderers[$ext]) || is_string($this->renderers[$ext])) {
$this->renderers[$ext] = Yii::createObject($this->renderers[$ext]);
}
/* @var $renderer ViewRenderer */
$renderer = $this->renderers[$ext];//如果支持的，将view渲染器对象赋值给$renderer
$output = $renderer->render($this, $viewFile, $params);//渲染视图文件
} else {//如果视图文件不是支持的类型，则以普通php文件处理
$output = $this->renderPhpFile($viewFile, $params);
}
$this->afterRender($viewFile, $params, $output);//调用renderFile的后置方法
}
array_pop($this->_viewFiles);//删除viewFiles中最后面的一个元素
$this->context = $oldContext;
return $output;
}