211 lines
4.1 KiB
Markdown
Executable File
211 lines
4.1 KiB
Markdown
Executable File
---
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title: 💫设计模式-工厂模式
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date: 2023-09-02
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tags:
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- 设计模式
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---
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**工厂模式**是一种创建型设计模式， 其在父类中提供一个创建对象的方法， 允许子类决定实例化对象的类型。
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## 需求的场景
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这种模式在面试中经常会被问到，很多面试题的答案会表示该模式经常用于框架的db或cache组件设计。
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假设你所在项目组在开发某个项目中，使用了多种缓存数据源，比如有内存，redis，本地文件。目前每次根据不同场景使用不同类型缓存，需要实例化不同缓存实例进行操作，比较繁琐。项目组开发人员希望统一调用缓存入口，简化缓存调用心智负担。
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### 如何解决
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1. 定义cache工厂类(父类)和依赖类
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2. 编写各个类型cache子类
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3. cache工厂类创建调用
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<!--more-->
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### 实现
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>
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> 这边实现使用PHP代码作为演示，其他oop语言逻辑类似。
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**😼1.定义cache工厂类(父类)和依赖类**
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```php
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// config 配置类 用于缓存实例化依赖配置数据
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class Config
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{
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private string $host; //连接host
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private string $dbName;// 数据库名称
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private string $password;// 密码
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private string $userName;// 用户名
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private int $port; //端口
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public function getHost(): string
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{
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return $this->host;
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}
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public function setHost(string $host): static
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{
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$this->host = $host;
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return $this;
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}
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public function getDbName(): string
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{
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return $this->dbName;
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}
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public function setDbName(string $dbName): static
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{
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$this->dbName = $dbName;
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return $this;
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}
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public function getPassword(): string
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{
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return $this->password;
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}
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public function setPassword(string $password): static
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{
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$this->password = $password;
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return $this;
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}
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public function getUserName(): string
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{
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return $this->userName;
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}
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public function setUserName(string $userName): static
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{
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$this->userName = $userName;
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return $this;
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}
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public function getPort(): string
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{
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return $this->port;
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}
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public function setPort(int $port): static
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{
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$this->port = $port;
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return $this;
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}
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}
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// 工厂类
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class Cache
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{
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protected Config $config;
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public function __construct(Config $config)
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{
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//通过构造注入Config依赖
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$this->config = $config;
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}
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public static create(string $cache)
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{
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//创建实例
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return new $cache($this->config);
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}
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}
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```
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**😸2.编写各个类型cache子类**
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```php
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// redis
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class Redis extends Cache
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{
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private Redis $redis
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public function __construct(Config $config)
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{
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parent::__construct(Config $config);
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$this->connect()
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}
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protected function connect()
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{
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//根据Config进行缓存连接
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$this->redis = new \Redis();
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// 连接 Redis 服务器
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$this->redis->connect($this->config->getHost() , $this->config->getPort() ?? 6379);
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// 可选：设置 Redis 密码
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$this->redis->auth($this->config->getPassword());
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}
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// 动态调用redis 方法
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public function __call($method, ...$arguments) {
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call_user_func([$this->redis, $method], ...$arguments);
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}
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}
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//内存
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class Memory extends Cache
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{
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public function __construct(Config $config)
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{
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parent::__construct(Config $config);
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}
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}
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//文件
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class File extends Cache
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{
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private string $cachePath = '/dev/logs/'
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public function __construct(Config $config)
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{
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parent::__construct(Config $config);
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}
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}
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```
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**😺3.cache工厂类创建调用**
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```php
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class Demo
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{
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public function run()
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{
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$config = (new Config())->setHost('localhost')
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->setUserName('demo')
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->setPassword('*****');
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$cache = new Cache($config);
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//创建redis cache实例
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$redis = $cache->create(Redis::class);
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//创建本地file cache实例
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$file = $cache->create(File::class);
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}
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}
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```
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