mvc架构模式思想

1.MVC (一种架构模式)
使用MVC的目的是将M和V的实现代码分离，从而使同一个程序可以使用不同的表现形式。
M: Model(模型层),最bottom一层,是核心数据层,程序需要操作的数据或信息.
V:View (视图层),最top一层,直接面向最终用户,视图层提供操作页面给用户,被誉为程序的外壳.
C: Controller(控制层),是middile层, 它负责根据用户从”视图层”输入的指令，选取”数据层”中的数据，然后对其进行相应的操作，产生最终结果。

模型层-model.php

<?php
class Model
{
    public function getData()
    {
        $dsn = 'mysql:host=127.0.0.1;port=3306;dbname=user';
        $username = 'root';
        $password = 'root123';
        $pdo = new PDO($dsn, $username, $password);
        $sql = "select `username`,`sex` from `users` order by `id` asc limit 5";
        $stmt = $pdo->query($sql);
        $res = $stmt->fetchAll(PDO::FETCH_ASSOC);
        return $res;
    }
}

视图层-view.php

<?php
class Model
{
    public function getData()
    {
        $dsn = 'mysql:host=127.0.0.1;port=3306;dbname=user';
        $username = 'root';
        $password = 'root123';
        $pdo = new PDO($dsn, $username, $password);
        $sql = "select `username`,`sex` from `users` order by `id` asc limit 5";
        $stmt = $pdo->query($sql);
        $res = $stmt->fetchAll(PDO::FETCH_ASSOC);
        return $res;
    }
}
视图层-view.php
<?php
class View
{
    public function fetch($data)
    {
        $html = <<<EOF
        <table>
            <caption>用户信息表</caption>
            <thead>
            <tr>
                <td>用户名</td>
                <td>性别</td>
            </tr>
            </thead>
            <tbody>
EOF;
        foreach ($data as $user) {
            $html .= "
            <tr>
                <td>{$user['username']}</td>
                <td>{$user['sex']}</td>
            </tr>";
        }
        $html .= "            </tbody>
        </table>";
    return $html;
    }
}

控制层-controller.php
<?php
require 'auto_load.php';
class Controller
{
    public function fetch()
    {
        $data = (new Model())->getData();
        echo (new View())->fetch($data);
    }
}
// 客户端
(new Controller())->fetch();

2.容器与依赖注入
依赖注入是通过 php 的映射函数，解析到类在实例化的时候所依赖的类，直接将类实例化
容器对依赖注入的类\对象等进行统一接管的一个工厂
容器类-container.php
class Container
{
    // 1. 对象容器
    protected $instances = [];
    // 2. 绑定一个类、闭包、实例、接口实现到容器
    public function bind($abstract, Closure $concrete)
    {
        $this->instances[$abstract] = $concrete;
    }
    // 3. 调用容器中对象
    public function make($abstract, $params=[])
    {
        return call_user_func_array($this->instances[$abstract], $params);
    }
}
控制器-controller3.php
require 'auto_load.php';
class Controller3
{
    public function fetch(Container $container)
    {
        $data = $container->make('model')->getData();
        return $container->make('view')->fetch($data);
    }
}
$container = new Container();
//绑定类到容器
$container->bind('model', function () {
    return new Model();
});
$container->bind('view', function () {
    return new View();
});
// 输出
echo (new Controller3())->fetch($container);
3.facade门面
Facade门面技术: 就是将服务容器中的对象的访问进行静态接管
Facade类 Facade.php
class Facade
{
    //为容器中的类提供一种静态调用方式
    protected static $container;
    public static function initialize(Container $container)
    {
        static::$container = $container;
    }
}
UserModel类继承facade
class UserModel extends Facade
{
    public static function getData()
    {
        //静态绑定
        return static::$container->make('model')->getData();
    }
}
UserView类继承facade
class UserView extends Facade
{
    public static function fetch($data)
    {
        //静态绑定
        return static::$container->make('view')->fetch($data);
    }
}
控制器controller3.php
require 'auto_load.php';
class Controller2
{
    public function __construct(Container $container)
    {
        Facade::initialize($container);
    }
    public function fetch()
    {
        $data = UserModel::getData();
        return UserView::fetch($data);
    }
}
$container = new Container;
// 类绑定到容器
$container->bind('model', function () {
    return new Model();
});
$container->bind('view', function () {
    return new View();
});
// 输出
echo (new Controller2($container))->fetch();