opencart整体架构分析

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opencart是一个完全免费的开源系统，采用MVCL的框架

整体概述

1：opencart是单一入口系统，所有的请求都要经过index.php文件来处理

2：系统框架对当前的url进行分析，找到对应的controller(控制器)和action(动作),去调用控制器文件里面的动作方法，url路径是调用各个文件的关键

3：在action动作中可以读取数据，处理业务逻辑，然后把完成的数据渲染到视图，给终端用户呈现出来

目录结构

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├── admin                   管理后台目录
│   ├── config.php          配置文件
│   ├── controller          控制器目录
│   ├── index.php           入口文件
│   ├── language            语言目录
│   ├── model               model目录
│   ├── php.ini             php配置文件
│   └── view                模板目录
├── catalog                 商店前台目录
│   ├── controller          控制器目录
│   ├── language            语言目录
│   ├── model               model目录
│   └── view                模板目录
├── config.php              配置文件
├── image                   图片目录
│   ├── cache               图片缓存目录
│   ├── catalog             图片上传目录
│   ├── no_image.png        
│   ├── payment             
│   └── placeholder.png
├── index.php               商店前台入口文件
├── install                 安装目录
│   ├── cli_install.php
│   ├── controller
│   ├── index.php
│   ├── language
│   ├── model
│   ├── opencart.sql
│   ├── php.ini
│   └── view
├── maintenance.html
├── php.ini
└── system                  系统框架目录
    ├── config              配置文件目录
    ├── engine              引擎目录
    ├── framework.php       框架文件     
    ├── helper              一些帮助文件
    ├── library             一些函数库
    ├── modification.xml
    ├── startup.php         启动文件
    └── storage             日志和缓存数据目录

流程分析

我们来从源码的角度看一下,(注：源码只截取关键部分)

在浏览器端键入如下的opencart官网的url地址，到底会发生什么事情

1
https://demo.opencart.com/index.php?route=common/home

用户的http请求首先会被转发到这个index.php文件

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<?php
// Version
define('VERSION', '2.3.0.3_rc');            //版本号

// Configuration                            //包含config.php文件进来
if (is_file('config.php')) {
    require_once('config.php');
}

// Install                                  //没有安装完成就会走安装的步骤
if (!defined('DIR_APPLICATION')) {
    header('Location: install/index.php');
    exit;
}

// Startup
require_once(DIR_SYSTEM . 'startup.php');   //包含startup.php文件进来

start('catalog');                           //调用startup.php中的start函数

再看一下startup.php文件

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// Engine
//把engine目录下面的文件包含进来
require_once(modification(DIR_SYSTEM . 'engine/action.php'));
require_once(modification(DIR_SYSTEM . 'engine/controller.php'));
require_once(modification(DIR_SYSTEM . 'engine/event.php'));
require_once(modification(DIR_SYSTEM . 'engine/front.php'));
require_once(modification(DIR_SYSTEM . 'engine/loader.php'));
require_once(modification(DIR_SYSTEM . 'engine/model.php'));
require_once(modification(DIR_SYSTEM . 'engine/registry.php'));
require_once(modification(DIR_SYSTEM . 'engine/proxy.php'));

// Helper
// 把helper目录下面的文件包含进来
require_once(DIR_SYSTEM . 'helper/general.php');
require_once(DIR_SYSTEM . 'helper/utf8.php');
require_once(DIR_SYSTEM . 'helper/json.php');

function start($application_config) {
// 这是上面index.php调用的函数
// 这里又调用了framework.php
    require_once(DIR_SYSTEM . 'framework.php');
}

再看一下framework.php文件，这里会构造各种核心的类

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<?php
// Registry
// 单例模式，保存一些全局变量
$registry = new Registry();

// Config
$config = new Config();
// 加载system/config/default.php
$config->load('default');
// 加载system/config/catalog.php
$config->load($application_config);
$registry->set('config', $config);

// Event
$event = new Event($registry);
$registry->set('event', $event);

// Event Register
// 一些预定义的拦截事件
if ($config->has('action_event')) {
	foreach ($config->get('action_event') as $key => $value) {
		$event->register($key, new Action($value));
	}
}

// Loader
$loader = new Loader($registry);
$registry->set('load', $loader);

// Request
$registry->set('request', new Request());

// Response
$response = new Response();
$response->addHeader('Content-Type: text/html; charset=utf-8');
$registry->set('response', $response);

// Database
...

// Front Controller
// 构造一个系统控制器Front
$controller = new Front($registry);

// Dispatch 
// 控制器分发action
// default.php配置文件里面 
// 'action_router' = 'startup/router'
// 'action_error' = 'error/not_found'
$controller->dispatch(new Action($config->get('action_router')), new Action($config->get('action_error')));

// Output
// 返回数据给用户
$response->setCompression($config->get('config_compression'));
$response->output();

看一下Front这个系统controller里面是怎么查找具体的action的

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<?php
final class Front {
	private $registry;
	private $pre_action = array();
	private $error;

	public function __construct($registry) {
		$this->registry = $registry;
	}
	
	public function dispatch(Action $action, Action $error) {
		$this->error = $error;

                ...
        
		while ($action instanceof Action) {
			$action = $this->execute($action); //转调execute
		}
	}

	private function execute(Action $action) {
		$result = $action->execute($this->registry); //调用Action的execute方法

		if ($result instanceof Action) {
			return $result;
		} 
		
		if ($result instanceof Exception) {
			$action = $this->error;
			
			$this->error = null;
			
			return $action;
		}
	}
}

看一下Action是的execute方法

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<?php
class Action {
	private $id;
	private $route;
	private $method = 'index'; //默认的函数是index

	public function __construct($route) {
		$this->id = $route;
		
		$parts = explode('/', preg_replace('/[^a-zA-Z0-9_\/]/', '', (string)$route));

		// Break apart the route
		while ($parts) {
			$file = DIR_APPLICATION . 'controller/' . implode('/', $parts) . '.php';

			if (is_file($file)) {
				$this->route = implode('/', $parts);		
				
				break;
			} else {
				$this->method = array_pop($parts); //找到controller后面的第一个part就是函数
			}
		}
	}
	public function execute($registry, array $args = array()) {
		// 这里的$this->route就是上面传入的'startup/router'
		// DIR_APPLICATION 是catalog的目录
		// 这个$file最终就是找到catalog/controller/startup/router.php文件
		$file = DIR_APPLICATION . 'controller/' . $this->route . '.php';		
		//$class构造出ControllerStartupRouter这个类
		$class = 'Controller' . preg_replace('/[^a-zA-Z0-9]/', '', $this->route);
		
		// Initialize the class
		if (is_file($file)) {
			include_once($file);
		
			$controller = new $class($registry); //构造类
		} else {
			return new \Exception('Error: Could not call ' . $this->route . '/' . $this->method . '!');
		}
		
		$reflection = new ReflectionClass($class);
		
		if ($reflection->hasMethod($this->method) && $reflection->getMethod($this->method)->getNumberOfRequiredParameters() <= count($args)) {
			//调controller相应的函数方法
			return call_user_func_array(array($controller, $this->method), $args);
		} else {
			return new \Exception('Error: Could not call ' . $this->route . '/' . $this->method . '!');
		}
	}

下面看一下startup/router这个控制器的实现

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<?php
class ControllerStartupRouter extends Controller {
	public function index() {
		// Route
		// https://demo.opencart.com/index.php?route=common/home
		// 获取url地址中的route值route=common/home
		if (isset($this->request->get['route']) && $this->request->get['route'] != 'startup/router') {
			$route = $this->request->get['route'];
		} else {
			$route = $this->config->get('action_default');
		}
		
		// Sanitize the call
		$route = preg_replace('/[^a-zA-Z0-9_\/]/', '', (string)$route);
		
		// Trigger the pre events
		$result = $this->event->trigger('controller/' . $route . '/before', array(&$route, &$data));
		
		if (!is_null($result)) {
			return $result;
		}
		
		// We dont want to use the loader class as it would make an controller callable.
		//构造一个'common/home'的action，参考上面action的分析
		$action = new Action($route);
		
		// Any output needs to be another Action object.
		$output = $action->execute($this->registry); 
		
		// Trigger the post events
		$result = $this->event->trigger('controller/' . $route . '/after', array(&$route, &$data, &$output));
		
		if (!is_null($result)) {
			return $result;
		}
		
		return $output;
	}
}

下面看一下common/home的controller代码具体做的事情

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<?php
class ControllerCommonHome extends Controller {
	public function index() {
		$this->document->setTitle($this->config->get('config_meta_title'));
		$this->document->setDescription($this->config->get('config_meta_description'));
		$this->document->setKeywords($this->config->get('config_meta_keyword'));

		if (isset($this->request->get['route'])) {
			$this->document->addLink($this->config->get('config_url'), 'canonical');
		}

		// 取数据，把数据保存到data变量中，在view模板中使用
		$data['column_left'] = $this->load->controller('common/column_left');
		$data['column_right'] = $this->load->controller('common/column_right');
		$data['content_top'] = $this->load->controller('common/content_top');
		$data['content_bottom'] = $this->load->controller('common/content_bottom');
		$data['footer'] = $this->load->controller('common/footer');
		$data['header'] = $this->load->controller('common/header');

		// 用数据渲染模板
		// 把模板输出到response对象中
		$this->response->setOutput($this->load->view('common/home', $data));
	}
}

再来看一下在loader.php里面，view是怎么加载的

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<?php
final class Loader {
	public function view($route, $data = array()) {
		$output = null;
		
		// Sanitize the call
		$route = preg_replace('/[^a-zA-Z0-9_\/]/', '', (string)$route);
		
		// Trigger the pre events
		// 加载预定义的模板，默认模板也是在这里加载的
		$result = $this->registry->get('event')->trigger('view/' . $route . '/before', array(&$route, &$data, &$output));
		
		if ($result) {
			return $result;
		}
		
		if (!$output) {
			//构造Template对象
			$template = new Template($this->registry->get('config')->get('template_type'));
			
			foreach ($data as $key => $value) {
				$template->set($key, $value);
			}
			//调用template对象的render函数
			$output = $template->render($route . '.tpl');
		}
		
		// Trigger the post events
		$result = $this->registry->get('event')->trigger('view/' . $route . '/after', array(&$route, &$data, &$output));
		
		if ($result) {
			return $result;
		}
		
		return $output;
	}

再看下Template是怎么渲染模板的,这里是用php原生方式来渲染

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<?php
namespace Template;
final class PHP {
	private $data = array();
	
	public function set($key, $value) {
		$this->data[$key] = $value;
	}
	
	public function render($template) {
		$file = DIR_TEMPLATE . $template;   //找到对应的模板文件

		if (is_file($file)) {
			extract($this->data);

			ob_start();

			require($file);                 //把文件包含进来

			return ob_get_clean();          //返回文件内容
		}

		trigger_error('Error: Could not load template ' . $file . '!');
		exit();
	}	
}

最后response对象把数据echo给用户

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<?php
class Response {
        //重定向
	public function redirect($url, $status = 302) {
		header('Location: ' . str_replace(array('&amp;', "\n", "\r"), array('&', '', ''), $url), true, $status);
		exit();
	}
	//把数据echo给用户
	public function output() {
	    if ($this->output) {
			$output = $this->level ? $this->compress($this->output, $this->level) : $this->output;
			if (!headers_sent()) {
				foreach ($this->headers as $header) {
					header($header, true);
				}
			}
			echo $output;
		}
	}