PHP 生成器模式讲解和代码示例

<?php namespace RefactoringGuru\Builder\Conceptual; /** * The Builder interface specifies methods for creating the different parts of * the Product objects. */ interface Builder { public function producePartA(): void; public function producePartB(): void; public function producePartC(): void; } /** * The Concrete Builder classes follow the Builder interface and provide * specific implementations of the building steps. Your program may have several * variations of Builders, implemented differently. */ class ConcreteBuilder1 implements Builder { private $product; /** * A fresh builder instance should contain a blank product object, which is * used in further assembly. */ public function __construct() { $this->reset(); } public function reset(): void { $this->product = new Product1(); } /** * All production steps work with the same product instance. */ public function producePartA(): void { $this->product->parts[] = "PartA1"; } public function producePartB(): void { $this->product->parts[] = "PartB1"; } public function producePartC(): void { $this->product->parts[] = "PartC1"; } /** * Concrete Builders are supposed to provide their own methods for * retrieving results. That's because various types of builders may create * entirely different products that don't follow the same interface. * Therefore, such methods cannot be declared in the base Builder interface * (at least in a statically typed programming language). Note that PHP is a * dynamically typed language and this method CAN be in the base interface. * However, we won't declare it there for the sake of clarity. * * Usually, after returning the end result to the client, a builder instance * is expected to be ready to start producing another product. That's why * it's a usual practice to call the reset method at the end of the * `getProduct` method body. However, this behavior is not mandatory, and * you can make your builders wait for an explicit reset call from the * client code before disposing of the previous result. */ public function getProduct(): Product1 { $result = $this->product; $this->reset(); return $result; } } /** * It makes sense to use the Builder pattern only when your products are quite * complex and require extensive configuration. * * Unlike in other creational patterns, different concrete builders can produce * unrelated products. In other words, results of various builders may not * always follow the same interface. */ class Product1 { public $parts = []; public function listParts(): void { echo "Product parts: " . implode(', ', $this->parts) . "\n\n"; } } /** * The Director is only responsible for executing the building steps in a * particular sequence. It is helpful when producing products according to a * specific order or configuration. Strictly speaking, the Director class is * optional, since the client can control builders directly. */ class Director { /** * @var Builder */ private $builder; /** * The Director works with any builder instance that the client code passes * to it. This way, the client code may alter the final type of the newly * assembled product. */ public function setBuilder(Builder $builder): void { $this->builder = $builder; } /** * The Director can construct several product variations using the same * building steps. */ public function buildMinimalViableProduct(): void { $this->builder->producePartA(); } public function buildFullFeaturedProduct(): void { $this->builder->producePartA(); $this->builder->producePartB(); $this->builder->producePartC(); } } /** * The client code creates a builder object, passes it to the director and then * initiates the construction process. The end result is retrieved from the * builder object. */ function clientCode(Director $director) { $builder = new ConcreteBuilder1(); $director->setBuilder($builder); echo "Standard basic product:\n"; $director->buildMinimalViableProduct(); $builder->getProduct()->listParts(); echo "Standard full featured product:\n"; $director->buildFullFeaturedProduct(); $builder->getProduct()->listParts(); // Remember, the Builder pattern can be used without a Director class. echo "Custom product:\n"; $builder->producePartA(); $builder->producePartC(); $builder->getProduct()->listParts(); } $director = new Director(); clientCode($director); 

Standard basic product: Product parts: PartA1 Standard full featured product: Product parts: PartA1, PartB1, PartC1 Custom product: Product parts: PartA1, PartC1