1. 前言

在看了一些容器实现代码后, 就手痒想要自己实现一个, 因此也就有了本文接下来的内容.

首先, 实现的容器需要具有以下几点特性:

符合PSR-11标准
实现基本的容器存储功能
具有自动依赖解决能力

本项目代码由GitHub托管

可使用Composer进行安装 composer require yjx/easy-di

2. 项目代码结构

|-src
    |-Exception
        |-InstantiateException.php (实现Psr\Container\ContainerExceptionInterface)
        |-InvalidArgumentException.php (实现Psr\Container\ContainerExceptionInterface)
        |-UnknownIdentifierException.php (实现Psr\Container\NotFoundExceptionInterface)
    |-Container.php # 容器|-tests
    |-UnitTest
        |-ContainerTest.php

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3. 容器完整代码

代码版本 v1.0.1

<?php
namespace EasyDI;
use EasyDI\Exception\UnknownIdentifierException;
use EasyDI\Exception\InvalidArgumentException;
use EasyDI\Exception\InstantiateException;
use Psr\Container\ContainerExceptionInterface;
use Psr\Container\ContainerInterface;use Psr\Container\NotFoundExceptionInterface;
class Container implements ContainerInterface{
    /**
     * 保存 参数, 已实例化的对象
     * @var array
     */
    private $instance = [];    private $shared = [];    private $raw = [];    private $params = [];    /**
     * 保存 定义的 工厂等
     * @var array
     */
    private $binding = [];    public function __construct()
    {
        $this->raw(ContainerInterface::class, $this);
        $this->raw(self::class, $this);
    }


    /**
     * Finds an entry of the container by its identifier and returns it.
     *
     * @param string $id Identifier of the entry to look for.
     *
     * @throws NotFoundExceptionInterface  No entry was found for **this** identifier.
     * @throws ContainerExceptionInterface Error while retrieving the entry.
     *
     * @return mixed Entry.
     */    public function get($id, $parameters = [], $shared=false)
    {
        if (!$this->has($id)) {            throw new UnknownIdentifierException($id);
        }        
        if (array_key_exists($id, $this->raw)) {            
        return $this->raw[$id];
        }        
        if (array_key_exists($id, $this->instance)) {            
        return $this->instance[$id];
        }        
        $define = array_key_exists($id, $this->binding) ? $this->binding[$id] : $id;        
        if ($define instanceof \Closure) {            
        $instance = $this->call($define, $parameters);
        } else {            
        // string
            $class = $define;            
            $params = (empty($this->params[$id]) ? [] : $this->params[$id]) + $parameters;            
            // Case: "\\xxx\\xxx"=>"abc"
            if ($id !== $class && $this->has($class)) {                
            $instance = $this->get($class, $params);
            } else {                
            $dependencies = $this->getClassDependencies($class, $params);                
            if (is_null($dependencies) || empty($dependencies)) {                    
            $instance = $this->getReflectionClass($class)->newInstanceWithoutConstructor();
                } else {                    
                $instance = $this->getReflectionClass($class)->newInstanceArgs($dependencies);
                }
            }
        }        if ($shared || (isset($this->shared[$id]) && $this->shared[$id])) {            
        $this->instance[$id] = $instance;
        }        return $instance;
    }    /**
     * @param callback $function
     * @param array $parameters
     * @return mixed
     * @throws InvalidArgumentException 传入错误的参数
     * @throws InstantiateException
     */
    public function call($function, $parameters=[], $shared=false)
    {
        //参考 http://php.net/manual/zh/function.call-user-func-array.php#121292 实现解析$function

        $class = null;        $method = null;        $object = null;        // Case1: function() {}
        if ($function instanceof \Closure) {            $method = $function;
        } elseif (is_array($function) && count($function)==2) {            // Case2: [$object, $methodName]
            if (is_object($function[0])) {                $object = $function[0];                $class = get_class($object);
            } elseif (is_string($function[0])) {                // Case3: [$className, $staticMethodName]
                $class = $function[0];
            }            if (is_string($function[1])) {                $method = $function[1];
            }
        } elseif (is_string($function) && strpos($function, &#39;::&#39;) !== false) {            // Case4: "class::staticMethod"
            list($class, $method) = explode(&#39;::&#39;, $function);
        } elseif (is_scalar($function)) {            // Case5: "functionName"
            $method = $function;
        } else {            throw new InvalidArgumentException("Case not allowed! Invalid Data supplied!");
        }        try {            if (!is_null($class) && !is_null($method)) {                $reflectionFunc = $this->getReflectionMethod($class, $method);
            } elseif (!is_null($method)) {                $reflectionFunc = $this->getReflectionFunction($method);
            } else {                throw new InvalidArgumentException("class:$class method:$method");
            }
        } catch (\ReflectionException $e) {//            var_dump($e->getTraceAsString());
            throw new InvalidArgumentException("class:$class method:$method", 0, $e);
        }        
        $parameters = $this->getFuncDependencies($reflectionFunc, $parameters);        
        if ($reflectionFunc instanceof \ReflectionFunction) {            
        return $reflectionFunc->invokeArgs($parameters);
        } elseif ($reflectionFunc->isStatic()) {            
        return $reflectionFunc->invokeArgs(null, $parameters);
        } elseif (!empty($object)) {            
        return $reflectionFunc->invokeArgs($object, $parameters);
        } elseif (!is_null($class) && $this->has($class)) {            
        $object = $this->get($class, [], $shared);            
        return $reflectionFunc->invokeArgs($object, $parameters);
        }        
        throw new InvalidArgumentException("class:$class method:$method, unable to invoke.");
    }    /**
     * @param $class
     * @param array $parameters
     * @throws \ReflectionException
     */
    protected function getClassDependencies($class, $parameters=[])
    {
        // 获取类的反射类
        $reflectionClass = $this->getReflectionClass($class);        
        if (!$reflectionClass->isInstantiable()) {            
        throw new InstantiateException($class);
        }        // 获取构造函数反射类
        $reflectionMethod = $reflectionClass->getConstructor();        
        if (is_null($reflectionMethod)) {            
        return null;
        }        
        return $this->getFuncDependencies($reflectionMethod, $parameters, $class);
    }    
    protected function getFuncDependencies(\ReflectionFunctionAbstract $reflectionFunc, $parameters=[], $class="")
    {
        $params = [];        // 获取构造函数参数的反射类
        $reflectionParameterArr = $reflectionFunc->getParameters();        
        foreach ($reflectionParameterArr as $reflectionParameter) {            
        $paramName = $reflectionParameter->getName();            
        $paramPos = $reflectionParameter->getPosition();            
        $paramClass = $reflectionParameter->getClass();            
        $context = [&#39;pos&#39;=>$paramPos, &#39;name&#39;=>$paramName, &#39;class&#39;=>$paramClass, &#39;from_class&#39;=>$class];            
        // 优先考虑 $parameters
            if (isset($parameters[$paramName]) || isset($parameters[$paramPos])) {                
            $tmpParam = isset($parameters[$paramName]) ? $parameters[$paramName] : $parameters[$paramPos];                
            if (gettype($tmpParam) == &#39;object&#39; && !is_a($tmpParam, $paramClass->getName())) {                    
            throw new InstantiateException($class."::".$reflectionFunc->getName(), $parameters + [&#39;__context&#39;=>$context, &#39;tmpParam&#39;=>get_class($tmpParam)]);
                }                
                $params[] = $tmpParam;//                
                $params[] = isset($parameters[$paramName]) ? $parameters[$paramName] : $parameters[$pos];
            } elseif (empty($paramClass)) {            
            // 若参数不是class类型

                // 优先使用默认值, 只能用于判断用户定义的函数/方法, 对系统定义的函数/方法无效, 也同样无法获取默认值
                if ($reflectionParameter->isDefaultValueAvailable()) {                    $params[] = $reflectionParameter->getDefaultValue();
                } elseif ($reflectionFunc->isUserDefined()) {                    
                throw new InstantiateException("UserDefined. ".$class."::".$reflectionFunc->getName());
                } elseif ($reflectionParameter->isOptional()) {                    break;
                } else {                    throw new InstantiateException("SystemDefined.  ".$class."::".$reflectionFunc->getName());
                }
            } else {            // 参数是类类型, 优先考虑解析
                if ($this->has($paramClass->getName())) {                    $params[] = $this->get($paramClass->getName());
                } elseif ($reflectionParameter->allowsNull()) {                    $params[] = null;
                } else {                    throw new InstantiateException($class."::".$reflectionFunc->getName()."  {$paramClass->getName()} ");
                }
            }
        }        return $params;
    }    protected function getReflectionClass($class, $ignoreException=false)
    {
        static $cache = [];        if (array_key_exists($class, $cache)) {            return $cache[$class];
        }        try {            $reflectionClass = new \ReflectionClass($class);
        } catch (\Exception $e) {            if (!$ignoreException) {                throw new InstantiateException($class, 0, $e);
            }            $reflectionClass = null;
        }        return $cache[$class] = $reflectionClass;
    }    protected function getReflectionMethod($class, $name)
    {
        static $cache = [];        if (is_object($class)) {            $class = get_class($class);
        }        if (array_key_exists($class, $cache) && array_key_exists($name, $cache[$class])) {            return $cache[$class][$name];
        }        $reflectionFunc = new \ReflectionMethod($class, $name);        return $cache[$class][$name] = $reflectionFunc;
    }    protected function getReflectionFunction($name)
    {
        static $closureCache;        static $cache = [];        $isClosure = is_object($name) && $name instanceof \Closure;        $isString = is_string($name);        if (!$isString && !$isClosure) {            throw new InvalidArgumentException("$name can&#39;t get reflection func.");
        }        if ($isString && array_key_exists($name, $cache)) {            return $cache[$name];
        }        if ($isClosure) {            if (is_null($closureCache)) {                $closureCache = new \SplObjectStorage();
            }            if ($closureCache->contains($name)) {                return $closureCache[$name];
            }
        }        $reflectionFunc = new \ReflectionFunction($name);        if ($isString) {            $cache[$name] = $reflectionFunc;
        }        if ($isClosure) {            $closureCache->attach($name, $reflectionFunc);
        }        return $reflectionFunc;
    }    /**
     * Returns true if the container can return an entry for the given identifier.
     * Returns false otherwise.
     *
     * `has($id)` returning true does not mean that `get($id)` will not throw an exception.
     * It does however mean that `get($id)` will not throw a `NotFoundExceptionInterface`.
     *
     * @param string $id Identifier of the entry to look for.
     *
     * @return bool
     */
    public function has($id)
    {
        $has = array_key_exists($id, $this->binding) || array_key_exists($id, $this->raw) || array_key_exists($id, $this->instance);        
        if (!$has) {            $reflectionClass = $this->getReflectionClass($id, true);            
        if (!empty($reflectionClass)) {                $has = true;
            }
        }        return $has;
    }    public function needResolve($id)
    {
        return !(array_key_exists($id, $this->raw) && (array_key_exists($id, $this->instance) && $this->shared[$id]));
    }    public function keys()
    {
        return array_unique(array_merge(array_keys($this->raw), array_keys($this->binding), array_keys($this->instance)));
    }    public function instanceKeys()
    {
        return array_unique(array_keys($this->instance));
    }    public function unset($id)
    {
        unset($this->shared[$id], $this->binding[$id], $this->raw[$id], $this->instance[$id], $this->params[$id]);
    }    public function singleton($id, $value, $params=[])
    {
        $this->set($id, $value, $params, true);
    }    /**
     * 想好定义数组, 和定义普通项
     * @param $id
     * @param $value
     * @param bool $shared
     */
    public function set($id, $value, $params=[], $shared=false)
    {
        if (is_object($value) && !($value instanceof  \Closure)) {            $this->raw($id, $value);            return;
        } elseif ($value instanceof \Closure) {            // no content
        } elseif (is_array($value)) {            $value = [                &#39;class&#39; => $id,                &#39;params&#39; => [],                &#39;shared&#39; => $shared
                ] + $value;            if (!isset($value[&#39;class&#39;])) {                $value[&#39;class&#39;] = $id;
            }            $params = $value[&#39;params&#39;] + $params;            $shared = $value[&#39;shared&#39;];            $value = $value[&#39;class&#39;];
        } elseif (is_string($value)) {            // no content
        }        $this->binding[$id] = $value;        $this->shared[$id] = $shared;        $this->params[$id] = $params;
    }    public function raw($id, $value)
    {
        $this->unset($id);        $this->raw[$id] = $value;
    }    public function batchRaw(array $data)
    {
        foreach ($data as $key=>$value) {            $this->raw($key, $value);
        }
    }    public function batchSet(array $data, $shared=false)
    {
        foreach ($data as $key=>$value) {            $this->set($key, $value, $shared);
        }
    }

}

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3.1 容器主要提供方法

容器提供方法:
- raw(string $id, mixed $value)
适用于保存参数, $value可以是任何类型, 容器不会对其进行解析.

set(string $id, \Closure|array|string $value, array $params=[], bool $shared=false)
定义服务
singleton(string $id, \Closure|array|string $value, array $params=[])
等同调用set($id, $value, $params, true)
has(string $id)
判断容器是否包含$id对应条目
get(string $id, array $params = [])
从容器中获取
params可优先参与到条目实例化过程中的依赖注入
call(callable $function, array $params=[])
利用容器来调用callable, 由容器自动注入依赖.
unset(string $id)
从容器中移除$id对应条目

3.2 符合PSR-11标准

EasyDI(本容器)实现了 Psr\Container\ContainerInterface 接口, 提供 has($id) 和 get($id, $params=[]) 两个方法用于判断及获取条目.

对于无法解析的条目识别符, 则会抛出异常(实现了 NotFoundExceptionInterface 接口).

3.3 容器的基本存储

容器可用于保存不被解析的条目, 及自动解析的条目.

不被解析的条目
主要用于保存 配置参数, 已实例化对象, 不被解析的闭包 等
自动解析的条目
在 get(...) 时会被容器自动解析, 若是闭包则会自动调用, 若是类名则会实例化, 若是别名则会解析其对应的条目.

3.4 自动依赖解决

EasyDI 在调用闭包及实例化类已经 调用函数/方法(call()) 时能够自动注入所需的依赖, 其中实现的原理是使用了PHP自带的反射API.

此处主要用到的反射API如下:

ReflectionClass
ReflectionFunction
ReflectionMethod
ReflectionParameter

3.4.1 解决类构造函数依赖

解析的一般步骤:

获取类的反射类 $reflectionClass = new ReflectionClass($className)
判断能够实例化 $reflectionClass->isInstantiable()
若能实例化, 则获取对应的构造函数的反射方法类 $reflectionMethod = $reflectionClass->getConstructor()
3.1. 若返回null, 则表示无构造函数可直接跳到步骤6
3.2 若返回ReflectionMethod实例, 则开始解析其参数
获取构造函数所需的所有依赖参数类 $reflectionParameters = $reflectionMethod->getParameters
逐个解析依赖参数 $reflectionParameter
5.1 获取参数对应名及位置 $reflectionParameter->getName(), $reflectionParameter->getClass()
5.2 获取参数对应类型 $paramClass = $reflectionParameter->getClass()
5.2.1 若本次解析手动注入了依赖参数, 则根据参数位置及参数名直接使用传入的依赖参数 Eg. $container->get($xx, [1=>123, 'e'=>new \Exception()])
5.2.2 若参数是标量类型, 若参数有默认值($reflectionParameter->isDefaultValueAvailable())则使用默认值, 否则抛出异常(无法处理该依赖)
5.2.3 若参数是 class 类型, 若容器可解析该类型, 则由容器自动实例化 $this->get($paramClass->getName()), 若无法解析但该参数允许null, 则传入null值, 否则抛出异常(无法处理来依赖)
若依赖参数为空则调用 $reflectionClass->newInstanceWithoutConstructor(), 否则调用 $reflectionClass->newInstanceArgs($dependencies); //$dependencies为步骤5中构造的依赖参数数组

具体完整代码请参照容器类的 getClassDependencies(...) 方法.

3.4.2 解决 callable 的参数依赖

使用 call(...) 来调用 可调用 时, 自动解决依赖同样类似上述过程, 只是需要区分是 类函数, 类静态方法 还是 普通方法, 并相应的使用不同的反射类来解析,

具体完整代码请参照容器类的 call(...) 方法

class UserManager{
    private $mailer;    public function __construct(Mailer $mailer)
    {
        $this->mailer = $mailer;
    }    public function register($email, $password)
    {
        // The user just registered, we create his account
        // ...

        // We send him an email to say hello!
        $this->mailer->mail($email, &#39;Hello and welcome!&#39;);
    }    public function quickSend(Mailer $mailer, $email, $password)
    {
        $mailer->mail($email, &#39;Hello and welcome!&#39;);
    }
}function testFunc(UserManager $manager){
    return "test";
}// 实例化容器$c = new EasyDI\Container();// 输出: &#39;test&#39;echo $c->call(&#39;testFunc&#39;)."\n";    

// 输出: &#39;test&#39;echo $c->call(function (UserManager $tmp) {
    return &#39;test&#39;;
}); 

// 自动实例化UserManager对象   [$className, $methodName]$c->call([UserManager::class, &#39;register&#39;], [&#39;password&#39;=>123, &#39;email&#39;=>&#39;1@1.1&#39;]);   

// 自动实例化UserManager对象   $methodFullName$c->call(UserManager::class.&#39;::&#39;.&#39;register&#39;, [&#39;password&#39;=>123, &#39;email&#39;=>&#39;1@1.1&#39;]); 

// 调用类的静态方法 [$className, $staticMethodName]
$c->call([UserManager::class, &#39;quickSend&#39;], [&#39;password&#39;=>123, &#39;email&#39;=>&#39;1@1.1&#39;]);  

// 使用字符串调用类的静态方法 $staticMethodFullName$c->call(UserManager::class.&#39;::&#39;.&#39;quickSend&#39;, [&#39;password&#39;=>123, &#39;email&#39;=>&#39;1@1.1&#39;]);    

// [$obj, $methodName] 
$c->call([new UserManager(new Mailer()), &#39;register&#39;], [&#39;password&#39;=>123, &#39;email&#39;=>&#39;1@1.1&#39;]);    

// [$obj, $staticMethodName]
$c->call([new UserManager(new Mailer()), &#39;quickSend&#39;], [&#39;password&#39;=>123, &#39;email&#39;=>&#39;1@1.1&#39;]);

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