What are containers and facades? A brief analysis of containers and facades in thinkphp5.1

This article brings you what is a container (Container) and a facade (Facade)? The brief analysis of containers and facades in thinkphp5.1 has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

p5.1 introduced two new classes, container (Container) and facade (Facade)

The official document has given the definition:

Container (Container) ) to achieve unified management of classes and ensure the uniqueness of object instances.

Facade provides a static calling interface for classes in the container (Container). Compared with traditional static method calling, it brings better testability and scalability. You can Any non-static class library defines a facade class.

Deep into the source code, let’s take a look at how it is implemented:

// 在框架目录下的base.php文件

// 注册核心类到容器
Container::getInstance()->bind([
    'app'                   => App::class,
    'build'                 => Build::class,
    'cache'                 => Cache::class,
    'config'                => Config::class,
    ...
]);

// 注册核心类的静态代理
Facade::bind([
    facade\App::class      => App::class,
    facade\Build::class    => Build::class,
    facade\Cache::class    => Cache::class,
    facade\Config::class   => Config::class,
    ...
]);

// 注册类库别名
Loader::addClassAlias([
    'App'      => facade\App::class,
    'Build'    => facade\Build::class,
    'Cache'    => facade\Cache::class,
    'Config'   => facade\Config::class,
    ...
]);

Container implementation:

Here, the framework has helped us bind common system classes to the container When using it later, you only need to call the helper function app() to perform class parsing calls in the container. The bound class identifier will be automatically and quickly instantiated.

// 实例化缓存类

app('cache'); 
// app('cache', ['file']); 参数化调用

// 相当于执行了
Container::get('cache');

// 查看源码，Container调用的其实是make方法，在该方法里调用反射等实现类的实例化，过程如下：

public function make($abstract, $vars = [], $newInstance = false)
{
    if (true === $vars) {
        // 总是创建新的实例化对象
        $newInstance = true;
        $vars        = [];
    }

    if (isset($this->instances[$abstract]) && !$newInstance) {
        $object = $this->instances[$abstract];
    } else {
        if (isset($this->bind[$abstract])) {
            $concrete = $this->bind[$abstract];
　　　　　　　// 闭包实现
            if ($concrete instanceof \Closure) {
                $object = $this->invokeFunction($concrete, $vars);
            } else {
                $object = $this->make($concrete, $vars, $newInstance);
            }
        } else {
　　　　　　　// 反射实现
            $object = $this->invokeClass($abstract, $vars);
        }

        if (!$newInstance) {
            $this->instances[$abstract] = $object;
        }
    }

    return $object;
}

/**
 * 调用反射执行类的实例化 支持依赖注入
 * @access public
 * @param  string    $class 类名
 * @param  array     $vars  变量
 * @return mixed
 */
public function invokeClass($class, $vars = [])
{
    $reflect     = new \ReflectionClass($class);
    $constructor = $reflect->getConstructor();

    if ($constructor) {
        $args = $this->bindParams($constructor, $vars);
    } else {
        $args = [];
    }

    return $reflect->newInstanceArgs($args);
}

/**
 * 执行函数或者闭包方法 支持参数调用
 * @access public
 * @param  string|array|\Closure $function 函数或者闭包
 * @param  array                 $vars     变量
 * @return mixed
 */
public function invokeFunction($function, $vars = [])
{
    $reflect = new \ReflectionFunction($function);
    $args    = $this->bindParams($reflect, $vars);

    return $reflect->invokeArgs($args);
}

In short, the instantiation of classes is implemented inside the container through reflection classes or closures.

Facade implementation:

Let’s analyze it with an example:

facade\Config::get('app_debug');

Let’s analyze its implementation:

// thinkphp\library\facade\Config 类

namespace think\facade;

use think\Facade;

class Config extends Facade
{
}

// From the source code There is no method in Config itself. It inherits the method of Facade, but Facade does not get this static method
// At this time, the system automatically triggers the magic method: __callStatic(), and Facade rewrites this method:

public static function __callStatic($method, $params)
{
    return call_user_func_array([static::createFacade(), $method], $params);
}

// It can be seen that the last call is the user-defined function: call_user_func_array([instance, method], parameter). In order to obtain the Config instance, Facade defines a method to obtain the object:

/**
 * 创建Facade实例
 * @static
 * @access protected
 * @param  string    $class          类名或标识
 * @param  array     $args           变量
 * @param  bool      $newInstance    是否每次创建新的实例
 * @return object
 */
protected static function createFacade($class = '', $args = [], $newInstance = false)
{
    $class       = $class ?: static::class;
    $facadeClass = static::getFacadeClass();

    if ($facadeClass) {
        $class = $facadeClass;
    } elseif (isset(self::$bind[$class])) {
        $class = self::$bind[$class];
    }

    if (static::$alwaysNewInstance) {
        $newInstance = true;
    }

    return Container::getInstance()->make($class, $args, $newInstance);
}

// The object is instantiated internally through the container
// Because the think\Config class has been bound to the config identifier in base.php

Container::getInstance()->bind([
　　'config'  => Config::class
])

// 在 createFacade 方法中，获取类的名称：$class = $class ?: static::class; 即得到 config 这个标识

// 在容器的make方法中，根据config标识，找到绑定的 think\Config 类，并调用其动态方法 get。

facade\Config::get('app_debug'); 

// 最后调用的是：

(new think\Config())->get('app_debug');

In short, The facade is implemented through PHP's magic method __callStatic, and then cooperates with the container to realize static calling of dynamic classes.

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