一、使用file方法根据模板路径来渲染
//src/Illuminate/View/Factory.php
/**
* Get the evaluated view contents for the given view.
*
* @param string $path
* @param array $data
* @param array $mergeData
* @return \Illuminate\Contracts\View\View
*/
public function file($path, $data = [], $mergeData = [])
{
$data = array_merge($mergeData, $this->parseData($data));
return tap($this->viewInstance($path, $path, $data), function ($view) {
$this->callCreator($view);
});
}首选使用parseData来将接收到的数据转化成可用于渲染的数据，目前是把实现了Arrayable接口的数据转化成数组，实现如下：
//src/Illuminate/View/Factory.php
/**
* Parse the given data into a raw array.
*
* @param mixed $data
* @return array
*/
protected function parseData($data)
{
return $data instanceof Arrayable ? $data->toArray() : $data;
}接下来使用viewInstance方法，创建一个View实例，紧接着触发creating: view名称事件。
二、使用make方法根据模板名称来渲染
与file不同的是，make方法只需要提供视图的名称，它就会在候选目录中找到对应的模板来渲染。
//src/Illuminate/View/Factory.php
/**
* Get the evaluated view contents for the given view.
*
* @param string $view
* @param array $data
* @param array $mergeData
* @return \Illuminate\Contracts\View\View
*/
public function make($view, $data = [], $mergeData = [])
{
$path = $this->finder->find(
$view = $this->normalizeName($view)
);
// Next, we will create the view instance and call the view creator for the view
// which can set any data, etc. Then we will return the view instance back to
// the caller for rendering or performing other view manipulations on this.
$data = array_merge($mergeData, $this->parseData($data));
return tap($this->viewInstance($view, $path, $data), function ($view) {
$this->callCreator($view);
});
}比file方法多出了下面这段用于查找模板路径的逻辑：
$path = $this->finder->find(
$view = $this->normalizeName($view)
);由于View名称是用.来分割目录的，所以normalizeName的作用就是把.转化成路径分隔符/。
三、使用first渲染第一个找到的view
//src/Illuminate/View/Factory.php
/**
* Get the first view that actually exists from the given list.
*
* @param array $views
* @param array $data
* @param array $mergeData
* @return \Illuminate\Contracts\View\View
*/
public function first(array $views, $data = [], $mergeData = [])
{
$view = collect($views)->first(function ($view) {
return $this->exists($view);
});
if (! $view) {
throw new InvalidArgumentException('None of the views in the given array exist.');
}
return $this->make($view, $data, $mergeData);
}其中$view参数就是一组待渲染的View名称，first方法的作用就是从候选目录中找这些view，渲染第一个找到的view。这在
模板覆盖的场景中可以用到。
四、使用renderWhen实现条件渲染
renderWhen的实现很简单，不满足条件直接返回空字符串。
//src/Illuminate/View/Factory.php
/**
* Get the rendered content of the view based on a given condition.
*
* @param bool $condition
* @param string $view
* @param array $data
* @param array $mergeData
* @return string
*/
public function renderWhen($condition, $view, $data = [], $mergeData = [])
{
if (! $condition) {
return '';
}
return $this->make($view, $this->parseData($data), $mergeData)->render();
}后面Blade中的@includeIf指令就使用了这个方法。
五、使用renderEach实现不同数据渲染同一份模板，并拼接所有结果
//src/Illuminate/View/Factory.php
/**
* Get the rendered contents of a partial from a loop.
*
* @param string $view
* @param array $data
* @param string $iterator
* @param string $empty
* @return string
*/
public function renderEach($view, $data, $iterator, $empty = 'raw|')
{
$result = '';
// If is actually data in the array, we will loop through the data and append
// an instance of the partial view to the final result HTML passing in the
// iterated value of this data array, allowing the views to access them.
if (count($data) > 0) {
foreach ($data as $key => $value) {
$result .= $this->make(
$view, ['key' => $key, $iterator => $value]
)->render();
}
}
// If there is no data in the array, we will render the contents of the empty
// view. Alternatively, the "empty view" could be a raw string that begins
// with "raw|" for convenience and to let this know that it is a string.
else {
$result = Str::startsWith($empty, 'raw|')
? substr($empty, 4)
: $this->make($empty)->render();
}
return $result;
}后面Blade指令中的@each指令就使用了这个方法。
这里比较有意思的地方是第四个参数，如果在$data为空的时候不需要渲染一个特定的视图，而只给出一段普通的字符串，那么可以传递
raw|$data为空时候显示的字符串，否则$empty参数就是模板名称。
六、使用exists方法判断对应名称的模板在候选目录中是否存在
//src/Illuminate/View/Factory.php
/**
* Determine if a given view exists.
*
* @param string $view
* @return bool
*/
public function exists($view)
{
try {
$this->finder->find($view);
} catch (InvalidArgumentException $e) {
return false;
}
return true;
}这里没有什么可讲的了，具体实现可以参考view-finder。
七、使用getEngineFromPath根据模板路径获取对应渲染引擎
//src/Illuminate/View/Factory.php
/**
* Get the appropriate view engine for the given path.
*
* @param string $path
* @return \Illuminate\Contracts\View\Engine
*
* @throws \InvalidArgumentException
*/
public function getEngineFromPath($path)
{
if (! $extension = $this->getExtension($path)) {
throw new InvalidArgumentException("Unrecognized extension in file: {$path}");
}
$engine = $this->extensions[$extension];
return $this->engines->resolve($engine);
}主要是根据模板名称的后缀，找到对应的渲染引擎的名称，然后使用engine-resolver来根据引擎名称找到对应的渲染引擎实例。
八、使用share方法实现视图间数据共享
//src/Illuminate/View/Factory.php
/**
* Add a piece of shared data to the environment.
*
* @param array|string $key
* @param mixed $value
* @return mixed
*/
public function share($key, $value = null)
{
$keys = is_array($key) ? $key : [$key => $value];
foreach ($keys as $key => $value) {
$this->shared[$key] = $value;
}
return $value;
}share方法主要是把数据放到$this->shared中，View在渲染的时候会通过factory的getShared方法找到所有共享数据，与普通数据组装以后
再做渲染。
九、候选目录与命名空间
//src/Illuminate/View/Factory.php
/**
* Add a location to the array of view locations.
*
* @param string $location
* @return void
*/
public function addLocation($location)
{
$this->finder->addLocation($location);
}
/**
* Add a new namespace to the loader.
*
* @param string $namespace
* @param string|array $hints
* @return $this
*/
public function addNamespace($namespace, $hints)
{
$this->finder->addNamespace($namespace, $hints);
return $this;
}
/**
* Prepend a new namespace to the loader.
*
* @param string $namespace
* @param string|array $hints
* @return $this
*/
public function prependNamespace($namespace, $hints)
{
$this->finder->prependNamespace($namespace, $hints);
return $this;
}
/**
* Replace the namespace hints for the given namespace.
*
* @param string $namespace
* @param string|array $hints
* @return $this
*/
public function replaceNamespace($namespace, $hints)
{
$this->finder->replaceNamespace($namespace, $hints);
return $this;
}具体实现可以参考view-finder
十、注册自定义渲染引擎
//src/Illuminate/View/Factory.php
/**
* Register a valid view extension and its engine.
*
* @param string $extension
* @param string $engine
* @param \Closure $resolver
* @return void
*/
public function addExtension($extension, $engine, $resolver = null)
{
$this->finder->addExtension($extension);
if (isset($resolver)) {
$this->engines->register($engine, $resolver);
}
unset($this->extensions[$extension]);
$this->extensions = array_merge([$extension => $engine], $this->extensions);
}其中$extension是自定义渲染引擎要渲染的模板文件的后缀， $engine为引擎名称，$resolver是一个根据引擎名称
返回对应引擎实例的函数。
十一、状态管理
//src/Illuminate/View/Factory.php
/**
* Increment the rendering counter.
*
* @return void
*/
public function incrementRender()
{
$this->renderCount++;
}
/**
* Decrement the rendering counter.
*
* @return void
*/
public function decrementRender()
{
$this->renderCount--;
}
/**
* Check if there are no active render operations.
*
* @return bool
*/
public function doneRendering()
{
return $this->renderCount == 0;
}
/**
* Flush all of the factory state like sections and stacks.
*
* @return void
*/
public function flushState()
{
$this->renderCount = 0;
$this->flushSections();
$this->flushStacks();
}
/**
* Flush all of the section contents if done rendering.
*
* @return void
*/
public function flushStateIfDoneRendering()
{
if ($this->doneRendering()) {
$this->flushState();
}
}在渲染一个入口视图的过程中，Factory本身保存很多状态，这些状态应该只属于本次渲染过程，所以它需要维护一套机制，在渲染过程结束以后， 重置这些状态，这样就不会影响到下一个入口视图的渲染。
系统在渲染一个视图之前，会调用incrementRender，渲染结束以后调用decrementRender，直到这个计数器为0，那么就表示入口视图已经
渲染好了，这也是doneRendering要做的事情。
flushState就是用来重置状态的。