模板方法模式定义了算法的骨架,具体步骤由子类实现,使子类可自定义具体步骤而无需改变整体结构。此模式用于:1. 定义算法的骨架。2. 将算法的具体行为延迟到子类。3. 允许子类自定义算法的某些步骤,而无需更改算法的总体结构。
PHP 中的模板方法模式
简介
模板方法模式是一种设计模式,它定义了算法的骨架,而具体步骤由子类具体实现。这使得子类可以自定义具体步骤,而无需改变算法的整体结构。
UML 图
+----------------+
| AbstractClass |
+----------------+
| + templateMethod() |
+----------------+
+----------------+
| ConcreteClass1 |
+----------------+
| + concreteMethod1() |
+----------------+
+----------------+
| ConcreteClass2 |
+----------------+
| + concreteMethod2() |
+----------------+
代码示例
AbstractClass.php
abstract class AbstractClass
{
public function templateMethod()
{
$this->step1();
$this->step2();
$this->hookMethod();
}
protected abstract function step1();
protected abstract function step2();
protected function hookMethod() {}
}
ConcreteClass1.php
class ConcreteClass1 extends AbstractClass
{
protected function step1()
{
echo "ConcreteClass1: Step 1<br>";
}
protected function step2()
{
echo "ConcreteClass1: Step 2<br>";
}
}
ConcreteClass2.php
class ConcreteClass2 extends AbstractClass
{
protected function step1()
{
echo "ConcreteClass2: Step 1<br>";
}
protected function step2()
{
echo "ConcreteClass2: Step 2<br>";
}
protected function hookMethod()
{
echo "ConcreteClass2: Hook Method<br>";
}
}
实战案例
假设我们有一个学生管理系统,我们需要创建两个页面:“学生列表”页面和“学生详情”页面。这两个页面使用相同的布局,但具体内容不同。
StudentManager.php
class StudentManager
{
public function showStudentList()
{
$students = // 获取学生数据
$view = new StudentListView();
$view->setStudents($students);
$view->render();
}
public function showStudentDetail($id)
{
$student = // 获取学生数据
$view = new StudentDetailView();
$view->setStudent($student);
$view->render();
}
}
StudentListView.php
class StudentListView extends AbstractView
{
private $students;
public function setStudents($students)
{
$this->students = $students;
}
public function render()
{
$this->showHeader();
$this->showStudents();
$this->showFooter();
}
protected function showStudents()
{
echo "<h1>学生列表</h1>";
echo "<ul>";
foreach ($this->students as $student) {
echo "<li>" . $student->getName() . "</li>";
}
echo "</ul>";
}
}
StudentDetailView.php
class StudentDetailView extends AbstractView
{
private $student;
public function setStudent($student)
{
$this->student = $student;
}
public function render()
{
$this->showHeader();
$this->showStudent();
$this->showFooter();
}
protected function showStudent()
{
echo "<h1>学生详情</h1>";
echo "<p>姓名:" . $this->student->getName() . "</p>";
echo "<p>年龄:" . $this->student->getAge() . "</p>";
}
}
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