Just for fun——PHP 框架之简单的路由器（1）

路由

路由的功能就是分发请求到不同的控制器，基于的原理就是正则匹配。接下来呢，我们实现一个简单的路由器，实现的能力是

对于静态的路由（没占位符的），正确调用callback
对于有占位符的路由，正确调用callback时传入占位符参数，譬如对于路由：/user/{id}，当请求为/user/23时，传入参数$args结构为
```
[
'id' => '23'
]
```
大致思路
我们需要把每个路由的信息管理起来：http方法（$method），路由字符串（$route），回调（$callback），因此需要一个addRoute方法，另外提供短方法get，post（就是把$method写好）
对于/user/{id}这样的有占位符的路由字符串，把占位符要提取出来，然后占位符部分变成正则字符串

实现

Route.php类

<?php

namespace SalamanderRoute;

class Route {
    /** @var string */
    public $httpMethod;

    /** @var string */
    public $regex;

    /** @var array */
    public $variables;

    /** @var mixed */
    public $handler;

    /**
     * Constructs a route (value object).
     *
     * @param string $httpMethod
     * @param mixed  $handler
     * @param string $regex
     * @param array  $variables
     */
    public function __construct($httpMethod, $handler, $regex, $variables) {
        $this->httpMethod = $httpMethod;
        $this->handler = $handler;
        $this->regex = $regex;
        $this->variables = $variables;
    }

    /**
     * Tests whether this route matches the given string.
     *
     * @param string $str
     *
     * @return bool
     */
    public function matches($str) {
        $regex = '~^' . $this->regex . '$~';
        return (bool) preg_match($regex, $str);
    }

}

Dispatcher.php

<?php
/**
 * User: salamander
 * Date: 2017/11/12
 * Time: 13:43
 */

namespace SalamanderRoute;

class Dispatcher {
    /** @var mixed[][] */
    protected $staticRoutes = [];

    /** @var Route[][] */
    private $methodToRegexToRoutesMap = [];

    const NOT_FOUND = 0;
    const FOUND = 1;
    const METHOD_NOT_ALLOWED = 2;

    /**
     * 提取占位符
     * @param $route
     * @return array
     */
    private function parse($route) {
        $regex = '~^(?:/[a-zA-Z0-9_]*|/\{([a-zA-Z0-9_]+?)\})+/?$~';
        if(preg_match($regex, $route, $matches)) {
            // 区分静态路由和动态路由
            if(count($matches) > 1) {
                preg_match_all('~\{([a-zA-Z0-9_]+?)\}~', $route, $matchesVariables);
                return [
                    preg_replace('~{[a-zA-Z0-9_]+?}~', '([a-zA-Z0-9_]+)', $route),
                    $matchesVariables[1],
                ];
            } else {
                return [
                    $route,
                    [],
                ];
            }
        }
        throw new \LogicException('register route failed, pattern is illegal');
    }

    /**
     * 注册路由
     * @param $httpMethod string | string[]
     * @param $route
     * @param $handler
     */
    public function addRoute($httpMethod, $route, $handler) {
        $routeData = $this->parse($route);
        foreach ((array) $httpMethod as $method) {
            if ($this->isStaticRoute($routeData)) {
                $this->addStaticRoute($httpMethod, $routeData, $handler);
            } else {
                $this->addVariableRoute($httpMethod, $routeData, $handler);
            }
        }
    }

    private function isStaticRoute($routeData) {
        return count($routeData[1]) === 0;
    }

    private function addStaticRoute($httpMethod, $routeData, $handler) {
        $routeStr = $routeData[0];

        if (isset($this->staticRoutes[$httpMethod][$routeStr])) {
            throw new \LogicException(sprintf(
                'Cannot register two routes matching "%s" for method "%s"',
                $routeStr, $httpMethod
            ));
        }

        if (isset($this->methodToRegexToRoutesMap[$httpMethod])) {
            foreach ($this->methodToRegexToRoutesMap[$httpMethod] as $route) {
                if ($route->matches($routeStr)) {
                    throw new \LogicException(sprintf(
                        'Static route "%s" is shadowed by previously defined variable route "%s" for method "%s"',
                        $routeStr, $route->regex, $httpMethod
                    ));
                }
            }
        }

        $this->staticRoutes[$httpMethod][$routeStr] = $handler;
    }

    private function addVariableRoute($httpMethod, $routeData, $handler) {
        list($regex, $variables) = $routeData;

        if (isset($this->methodToRegexToRoutesMap[$httpMethod][$regex])) {
            throw new \LogicException(sprintf(
                'Cannot register two routes matching "%s" for method "%s"',
                $regex, $httpMethod
            ));
        }

        $this->methodToRegexToRoutesMap[$httpMethod][$regex] = new Route(
            $httpMethod, $handler, $regex, $variables
        );
    }

    public function get($route, $handler) {
        $this->addRoute('GET', $route, $handler);
    }

    public function post($route, $handler) {
        $this->addRoute('POST', $route, $handler);
    }

    public function put($route, $handler) {
        $this->addRoute('PUT', $route, $handler);
    }

    public function delete($route, $handler) {
        $this->addRoute('DELETE', $route, $handler);
    }

    public function patch($route, $handler) {
        $this->addRoute('PATCH', $route, $handler);
    }

    public function head($route, $handler) {
        $this->addRoute('HEAD', $route, $handler);
    }

    /**
     * 分发
     * @param $httpMethod
     * @param $uri
     */
    public function dispatch($httpMethod, $uri) {
        $staticRoutes = array_keys($this->staticRoutes[$httpMethod]);
        foreach ($staticRoutes as $staticRoute) {
            if($staticRoute === $uri) {
                return [self::FOUND, $this->staticRoutes[$httpMethod][$staticRoute], []];
            }
        }

        $routeLookup = [];
        $index = 1;
        $regexes = array_keys($this->methodToRegexToRoutesMap[$httpMethod]);
        foreach ($regexes as $regex) {
            $routeLookup[$index] = [
                $this->methodToRegexToRoutesMap[$httpMethod][$regex]->handler,
                $this->methodToRegexToRoutesMap[$httpMethod][$regex]->variables,
            ];
            $index += count($this->methodToRegexToRoutesMap[$httpMethod][$regex]->variables);
        }
        $regexCombined = '~^(?:' . implode('|', $regexes) . ')$~';
        if(!preg_match($regexCombined, $uri, $matches)) {
            return [self::NOT_FOUND];
        }
        for ($i = 1; '' === $matches[$i]; ++$i);
        list($handler, $varNames) = $routeLookup[$i];
        $vars = [];
        foreach ($varNames as $varName) {
            $vars[$varName] = $matches[$i++];
        }
        return [self::FOUND, $handler, $vars];
    }
}

配置

nginx.conf重写到index.php

location / {
        try_files $uri $uri/ /index.php$is_args$args;

        # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
        #
        location ~ \.php$ {
            fastcgi_pass   127.0.0.1:9000;
            fastcgi_index  index.php;
            fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
            include        fastcgi_params;
        }

    }

composer.json自动载入

{
    "name": "salmander/route",
    "require": {},
    "autoload": {
      "psr-4": {
        "SalamanderRoute\\": "SalamanderRoute/"
      }
  }
}

最终使用

index.php

<?php

include_once 'vendor/autoload.php';

use SalamanderRoute\Dispatcher;

$dispatcher = new Dispatcher();

$dispatcher->get('/', function () {
    echo 'hello world';
});

$dispatcher->get('/user/{id}', function ($args) {
    echo "user {$args['id']} visit";
});

// Fetch method and URI from somewhere
$httpMethod = $_SERVER['REQUEST_METHOD'];
$uri = $_SERVER['REQUEST_URI'];

// 去掉查询字符串
if (false !== $pos = strpos($uri, '?')) {
    $uri = substr($uri, 0, $pos);
}

$routeInfo = $dispatcher->dispatch($httpMethod, $uri);
switch ($routeInfo[0]) {
    case Dispatcher::NOT_FOUND:
        echo '404 not found';
        break;
    case Dispatcher::FOUND:
        $handler = $routeInfo[1];
        $vars = $routeInfo[2];
        $handler($vars);
        break;
}