了解PHP容器(Container)的实现

看 Laravel 源代码了解 Container

Dependency Injection Containers 的基本功能：

• Container 管理对象实例化到配置的过程
• 对象本身不知道自己是由 Container 管理的，对 Container 一无所知。

这就是为什么 Container 能够管理任何 PHP 对象。 对象使用 DI 来管理依赖关系非常好，但不是必须的。

i

<?php
function info($msg){
    echo $msg;
}

class LogToFile {
    public function execute($message) {
        info('log the message to a 美羊羊 :'.$message);
    }
}

class UseLogger {
    protected $logger;

    public function __construct(LogToFile $logger) {
        $this->logger = $logger;
    }

    public function show() {
        $user = '小灰灰';
        $this->logger->execute($user);
    }
}

$useLogger = new UseLogger(new LogToFile());

$useLogger->show();

ii

A

<?php
 
function info($msg){
    echo $msg;
}


class LogToFile {
    public function execute($message) {
        info('log the message to a 美羊羊  :'.$message);
    }
}

class LogToDD {
    public function execute($message) {
        info('log the message to 喜羊羊 :'.$message);
    }
}

 
class UseLogger {
    protected $logger;

    public function __construct(LogToFile $logger) {
        $this->logger = $logger;
    }

    public function show() {
        $user = '小灰灰';
        $this->logger->execute($user);
    }
}
$useLogger = new UseLogger(new LogToFile());
 
$useLogger->show();

B

<?php
 
function info($msg){
    echo $msg;
}

class LogToFile {
    public function execute($message) {
        info('log the message to a 美羊羊  :'.$message);
    }
}

class LogToDD {
    public function execute($message) {
        info('log the message to 喜羊羊 :'.$message);
    }
}

 
class UseLogger {
    protected $logger;

    public function __construct(LogToDD $logger) {
        $this->logger = $logger;
    }

    public function show() {
        $user = '小灰灰';
        $this->logger->execute($user);
    }
}
$useLogger = new UseLogger(new LogToDD());
 
$useLogger->show();

iii

<?php

function info($msg){
    echo $msg;
}

interface Logger {
    public function execute($message);
}

class LogToFile implements Logger {
    public function execute($message) {
        info('log the message to a 美羊羊 :'.$message);
    }
}

class LogToDD implements Logger {
    public function execute($message) {
        info('log the message to 喜羊羊 :'.$message);
    }
}
 
class UseLogger {
    protected $logger;

    public function __construct(Logger $logger) {
        $this->logger = $logger;
    }

    public function show() {
        $user = '小灰灰';
        $this->logger->execute($user);
    }
}

$useLogger = new UseLogger(new LogToFile());
 
$useLogger->show();

echo '<br>';

$useLogger = new UseLogger(new LogToDD());
 
$useLogger->show();

终极版

<?php
 
function info($msg){
    echo $msg;
}

interface Logger {
    public function execute($message);
}

class LogToFile implements Logger {
    public function execute($message) {
        info('log the message to a 美羊羊 :'.$message);
    }
}

class LogToDD implements Logger {
    public function execute($message) {
        info('log the message to 喜羊羊 :'.$message);
    }
}
 
class UseLogger {
    protected $logger;

    public function __construct(Logger $logger) {
        $this->logger = $logger;
    }

    public function show() {
        $user = '小灰灰';
        $this->logger->execute($user);
 
    }
}

class SimpleContainer {

    // 用于存储所有绑定 key-value
    protected static $container = [];

    public static function bind($name, Callable $resolver) {
        static::$container[$name] = $resolver;
    }

    public static function make($name) {
        if(isset(static::$container[$name])){
            $resolver = static::$container[$name] ;
            return $resolver();
        }
        throw new Exception("Binding does not exist in container");
    }
}

SimpleContainer::bind(Logger::class, function () {
    return new LogToDD();
});

$useLogger3 = new UseLogger(SimpleContainer::make(Logger::class));


$useLogger3->show();

示例

<?php

interface SuperModuleInterface{
    public function activate(array $target);
}

class Superman
{
    protected $module;

    /**
     * Superman constructor.
     * @param SuperModuleInterface $module
     * 通过构造器 注入依赖
     */
    public function __construct(SuperModuleInterface $module)
    {
        $this->module = $module;
    }

    public function show(array $target){

        $this->module->activate($target);
    }
}

class PowerA implements SuperModuleInterface
{
    public function activate(array $target)
    {
        echo '<pre>'. __METHOD__;
        print_r(func_get_args());
    }
}

class PowerB implements SuperModuleInterface
{
    public function activate(array $target)
    {
        echo '<pre>'. __METHOD__;
        print_r(func_get_args());
    }
}



class Container
{
    protected $binds;

    protected $instances;

    /**
     * @param $abstract
     * @param $concrete
     * 把代词 绑定到容器里,为后续make
     */
    public function bind($abstract, $concrete)
    {
        if ($concrete instanceof Closure) {
            $this->binds[$abstract] = $concrete;
        } else {
            $this->instances[$abstract] = $concrete;
        }
    }

    /**
     * @param $abstract
     * @param array $parameters
     * @return mixed
     * 创建对象
     */
    public function make($abstract, $parameters = [])
    {
        if (isset($this->instances[$abstract])) {
            return $this->instances[$abstract];
        }
        // 把容器对象$this,放到参数数组第一个元素。为call_user_func_array使用
        array_unshift($parameters, $this);
        
        // 这里$this->binds[$abstract] 绑定的闭包函数, 执行函数参数是$parameters
        return call_user_func_array($this->binds[$abstract], $parameters);
    }
}


// 创建一个容器（后面称作超级工厂）
$container = new Container;


// 向该 超级工厂添加超能力模组的生产脚本
$container->bind('powerA', function($container) {
    return new PowerA;
});

// 同上
$container->bind('powerB', function($container) {
    return new PowerB;
});


// 向该 超级工厂添加超人的生产脚本
$container->bind('superman', function($container, $moduleName) {
    return new Superman($container->make($moduleName));
});



echo "<pre>";

// 开始启动生产
$superman_1 = $container->make('superman', ['powerA']);
$superman_1->show(['a' => 1]);

$superman_2 = $container->make('superman', ['powerB']);
$superman_2->show(['b' => 1]);