PHP 组合模式讲解和代码示例

<?php namespace RefactoringGuru\Composite\RealWorld; /** * The base Component class declares an interface for all concrete components, * both simple and complex. * * In our example, we'll be focusing on the rendering behavior of DOM elements. */ abstract class FormElement { /** * We can anticipate that all DOM elements require these 3 fields. */ protected $name; protected $title; protected $data; public function __construct(string $name, string $title) { $this->name = $name; $this->title = $title; } public function getName(): string { return $this->name; } public function setData($data): void { $this->data = $data; } public function getData(): array { return $this->data; } /** * Each concrete DOM element must provide its rendering implementation, but * we can safely assume that all of them are returning strings. */ abstract public function render(): string; } /** * This is a Leaf component. Like all the Leaves, it can't have any children. */ class Input extends FormElement { private $type; public function __construct(string $name, string $title, string $type) { parent::__construct($name, $title); $this->type = $type; } /** * Since Leaf components don't have any children that may handle the bulk of * the work for them, usually it is the Leaves who do the most of the heavy- * lifting within the Composite pattern. */ public function render(): string { return "<label for=\"{$this->name}\">{$this->title}</label>\n" . "<input name=\"{$this->name}\" type=\"{$this->type}\" value=\"{$this->data}\">\n"; } } /** * The base Composite class implements the infrastructure for managing child * objects, reused by all Concrete Composites. */ abstract class FieldComposite extends FormElement { /** * @var FormElement[] */ protected $fields = []; /** * The methods for adding/removing sub-objects. */ public function add(FormElement $field): void { $name = $field->getName(); $this->fields[$name] = $field; } public function remove(FormElement $component): void { $this->fields = array_filter($this->fields, function ($child) use ($component) { return $child != $component; }); } /** * Whereas a Leaf's method just does the job, the Composite's method almost * always has to take its sub-objects into account. * * In this case, the composite can accept structured data. * * @param array $data */ public function setData($data): void { foreach ($this->fields as $name => $field) { if (isset($data[$name])) { $field->setData($data[$name]); } } } /** * The same logic applies to the getter. It returns the structured data of * the composite itself (if any) and all the children data. */ public function getData(): array { $data = []; foreach ($this->fields as $name => $field) { $data[$name] = $field->getData(); } return $data; } /** * The base implementation of the Composite's rendering simply combines * results of all children. Concrete Composites will be able to reuse this * implementation in their real rendering implementations. */ public function render(): string { $output = ""; foreach ($this->fields as $name => $field) { $output .= $field->render(); } return $output; } } /** * The fieldset element is a Concrete Composite. */ class Fieldset extends FieldComposite { public function render(): string { // Note how the combined rendering result of children is incorporated // into the fieldset tag. $output = parent::render(); return "<fieldset><legend>{$this->title}</legend>\n$output</fieldset>\n"; } } /** * And so is the form element. */ class Form extends FieldComposite { protected $url; public function __construct(string $name, string $title, string $url) { parent::__construct($name, $title); $this->url = $url; } public function render(): string { $output = parent::render(); return "<form action=\"{$this->url}\">\n<h3>{$this->title}</h3>\n$output</form>\n"; } } /** * The client code gets a convenient interface for building complex tree * structures. */ function getProductForm(): FormElement { $form = new Form('product', "Add product", "/product/add"); $form->add(new Input('name', "Name", 'text')); $form->add(new Input('description', "Description", 'text')); $picture = new Fieldset('photo', "Product photo"); $picture->add(new Input('caption', "Caption", 'text')); $picture->add(new Input('image', "Image", 'file')); $form->add($picture); return $form; } /** * The form structure can be filled with data from various sources. The Client * doesn't have to traverse through all form fields to assign data to various * fields since the form itself can handle that. */ function loadProductData(FormElement $form) { $data = [ 'name' => 'Apple MacBook', 'description' => 'A decent laptop.', 'photo' => [ 'caption' => 'Front photo.', 'image' => 'photo1.png', ], ]; $form->setData($data); } /** * The client code can work with form elements using the abstract interface. * This way, it doesn't matter whether the client works with a simple component * or a complex composite tree. */ function renderProduct(FormElement $form) { // .. echo $form->render(); // .. } $form = getProductForm(); loadProductData($form); renderProduct($form); 

<form action="/product/add"> <h3>Add product</h3> <label for="name">Name</label> <input name="name" type="text" value="Apple MacBook"> <label for="description">Description</label> <input name="description" type="text" value="A decent laptop."> <fieldset><legend>Product photo</legend> <label for="caption">Caption</label> <input name="caption" type="text" value="Front photo."> <label for="image">Image</label> <input name="image" type="file" value="photo1.png"> </fieldset> </form>