php - 架构设计帮助 - OOP Solid Principle

Question

我正在尝试制作开源缓存库。库的目的是提供将变量(可以是对象，可以是数组，可以是任何东西)存储到文件然后在调用时检索它的方法。 (通常那些变量值是海量数据库查询和计算的结果)。

该项目的基本目标是实践称为 Solid 的面向对象设计原则。

如果有人能指出我在哪里违反了坚实的原则以及如何解决它

我完全理解 stackoverflow 不是一个代码编写服务，但是嘿，我正在将这个库开源，所以它会让我们的社区受益。

这是我的文件结构。

我是UML新手，所以如果发现任何错误请忽略

这是类的实现。

缓存

namespace library\pingle\cache;

use library\pingle\cache\config\CacheConfigurator;
use library\pingle\cache\file\FileHandler;

/**
 * @property CacheReader $cache_reader
 * @property CacheWriter $cache_write
 */
Class Cache {

    private $config;
    private $file_hander;
    private $cache_reader;
    private $cache_write;
    private $cache_directory;
    private $cache_kept_days;
    private $cache_file_prams;
    private $function_name;
    private $file_path;

    function __construct(CacheConfigurator $config) {
        $this->file_hander = new FileHandler();
        $this->config = $config;
        list($this->cache_directory, $this->function_name, $this->cache_kept_days, $this->cache_file_prams) = $this->config->getConfig();
        $this->file_path = $this->generateFileName($this->cache_file_prams);
    }

    public function read() {
        if (is_null($this->cache_reader)) {
            $this->cache_reader = new CacheReader($this->file_hander);
        }
        return $this->cache_reader->readCache($this->file_path);
    }

    public function write($data) {
        if (is_null($this->cache_write)) {
            $this->cache_write = new CacheWriter($this->file_hander);
        }
        if (!$this->file_hander->checkDirectory($this->cache_directory . "/" . $this->function_name)) {
            $this->file_hander->createDirectory($this->cache_directory . "/" . $this->function_name);
        }
        $this->cache_write->writeCache($this->file_path, $data);
    }

    public function check() {
        if ($this->file_hander->checkFileExits($this->file_path)) {
            if (time() - filemtime($this->file_path) >= 60 * 60 * 24 * $this->cache_kept_days) {
                return false;
            }
            return true;
        } else {
            return false;
        }
    }

    private function generateFileName(Array $nameprams) {
        $this->file_name = "";
        $file = "CC";
        foreach ($nameprams as $key => $value) {
            $file .= "-$key|$value-";
        }
        $file .= ".bak";
        return $this->cache_directory . "/" . $this->function_name . "/" . $file;
    }

}

抽象缓存

<?php

namespace library\pingle\cache;

use library\pingle\cache\file\FileHandler;

abstract Class AbstractCache {

    protected $file_handler;

    public function __construct(FileHandler $file_handler) {
        $this->file_handler = $file_handler;
    }

    protected function checkDirectory($path) {
        //check directory exists
        $dircheck = $this->file_handler->checkDirectory(dirname($path));
        if ($dircheck) {
            //check directory permission
            if ($this->file_handler->checkPermission(dirname($path))) {
                return true;
            } else {
                throw new \Exception("Directory ($path) Permission Error.");
            }
        } else {
            throw new \Exception("Directory ($path) not found.");
        }
    }

}

缓存读取器

<?php

namespace library\pingle\cache;

use library\pingle\cache\file\FileHandler;

/**
 * @property FileHandler $file_handler
 */
Class CacheReader extends AbstractCache {

    public function __construct(FileHandler $file_handler) {
        parent::__construct($file_handler);
    }

    public function readCache($path) {
        if ($this->checkDirectory($path)) {
            //delete the file if it exits
            if ($this->file_handler->checkFileExits($path)) {
                return $this->file_handler->readFile($path);
            } else {
                throw new \Exception("File ($path) not found");
            }
        }
    }

}

缓存写入器

<?php

namespace library\pingle\cache;

use library\pingle\cache\file\FileHandler;

/**
 * @property FileHandler $file_handler
 */
Class CacheWriter extends AbstractCache {

    public function __construct(FileHandler $file_handler) {
        parent::__construct($file_handler);
    }

    function writeCache($path, $data) {
        if ($this->checkDirectory($path)) {
            //delete the file if it exits
            if ($this->file_handler->checkFileExits($path)) {
                $this->file_handler->deleteFile($path);
            }
            //write cache
            $this->file_handler->writeFile($path, $data);
        }
    }

}

文件处理程序

<?php

namespace library\pingle\cache\file;

Class FileHandler {

    public function writeFile($path, $data) {
        $content = serialize($data);
        file_put_contents($path, $content);
    }

    public function createDirectory($path) {
        mkdir($path);
    }

    public function deleteFile($path) {
        unlink($path);
    }

    public function checkDirectory($path) {
        if (file_exists($path)) {
            return true;
        } else {
            return false;
        }
    }

    public function checkPermission($path) {
        if (is_writable($path)) {
            return true;
        } else {
            return false;
        }
    }

    public function checkFileExits($path) {
        if (is_file($path)) {
            return true;
        }
        return false;
    }

    public function readFile($path) {
        return unserialize(file_get_contents($path));
    }

    public function checkFileCreated($path, $format = "Y-m-d") {
        return date($format, filemtime($path));
    }

}

缓存配置器

<?php
namespace library\pingle\cache\config;
/**
 * @property PramsFormatter $prams_formatter
 */
class CacheConfigurator {
    private $prams_formatter;
    private $cache_directory;
    private $cache_kept_days;
    private $cache_file_prams;
    private $function_name;
    function __construct($file_prams) {
        $this->cache_file_prams = $file_prams;
        $this->cache_directory = ""; //Def Path
    }
    public function setCacheDirectory($cache_directory) {
        $this->cache_directory = $cache_directory;
        return $this;
    }
    public function setFunction($function) {
        $this->function_name = $function;
        return $this;
    }
    public function setCacheKeptDays($cache_kept_days) {
        $this->cache_kept_days = $cache_kept_days;
        return $this;
    }
    public function getConfig() {
        $this->prams_formatter = new PramsFormatter($this->cache_file_prams);
        $this->cache_file_prams = $this->prams_formatter->getFormattedPrams();
        $this->function_name = $this->prams_formatter->cleanValue($this->function_name);
        return array($this->cache_directory, $this->function_name, $this->cache_kept_days, $this->cache_file_prams);
    }
}

PramsFormatter

<?php

namespace library\pingle\cache\config;

class PramsFormatter {

    private $cache_file_prams;

    public function __construct(Array $prams) {
        $this->cache_file_prams = $prams;
        $this->formatPrams();
    }

    public function formatPrams() {
        if (is_array($this->cache_file_prams)) {
            foreach ($this->cache_file_prams as $k => $value) {
                $this->cache_file_prams[$k] = $this->cleanValue($value);
            }
        }
    }

    public function cleanValue($value) {
        if (is_array($value)) {
            throw new \Exception("Array as paramter value is not accepted");
        } else {
            return str_replace(array(" ", "   ", ".", "/", "\\"), "-", $value);
        }
    }

    public function getFormattedPrams() {
        return $this->cache_file_prams;
    }

}

用法

$cache_config = new CacheConfigurator(array('carrier_id' => $invoicedata['carrier_id'], 'month' => $month, 'year' => $year));
$cache_config->setFunction('Inter-department Calls');
$cache_config->setCacheKeptDays(30);
$cache_config->setCacheDirectory("bin/cache");
$cache = new Cache($cache_config);
if ($cache->check()) {
    $node = $cache->read();
} else {
    //calculate node
    $cache->write($node);
}

改进设计的 Git 存储库

https://github.com/FaizRasool/EPC

Answer 1

很好的问题，但是关于这个问题可能会写一整本书，所以很难回答。

我将从这个简单的问题开始:在下面的选项中，什么能更好地描述缓存？

1. 缓存是一种允许将函数结果存储到文件中数天以便提供快速访问的机制。

2. 缓存是一种机制，允许在满足相关保留策略的情况下保留操作结果，以便提供对其的快速访问。

没有一个定义是完美的，这不是重点，但我想强调的是，#1 用非常具体的基础设施细节解释了缓存，而 #2 以更抽象的方式定义了机制。

希望您现在已经意识到您设计 IMO 的最大缺陷之一。各种抽象都是错误的:

1. 存储机制的抽象依赖于特定的基础架构细节:整个 API 都围绕着文件。如果我想要一个内存缓存怎么办？

2. 数据保留策略算法非常具体:数据只会保留特定天数。如果我想在每次访问数据时计数器重置的分钟内表示缓存怎么办？

我给您的一个建议是始终挑战您的抽象并确保它们不太具体，这样您的代码就可以扩展和重用，但也不会太宽泛。注意问题域的语言对此有很大帮助。

显然可以说的远不止这些，有时依赖技术是正确的选择，但我认为我的回答会有所帮助...