Detailed explanation of PHP reflection mechanism

This article mainly shares with you a detailed explanation of the PHP reflection mechanism, including 1. Automatically generating documents 2. Implementing MVC architecture 3. Implementing unit testing 4. Cooperating with DI containers to resolve dependencies. I hope it can help everyone.

1. Automatically generate documents

Based on the reflection analysis of classes, interfaces, internal structures of functions and methods, parameters of methods and functions, and attributes and methods of classes, it can be automatically Generate documentation.

<?phpclass Student{
    const NORMAL = 1;    const FORBIDDEN = 2;    /**
     * 用户ID
     * @var 类型
     */
    public $id;    /**
     * 获取id
     * @return int
     */
    public function getId()
    {
        return $this->id;
    }    public function setId($id = 1)
    {
        $this->id = $id;
    }
}$ref = new ReflectionClass(&#39;Student&#39;);$doc = $ref->getDocComment();echo $ref->getName() . &#39;:&#39; . getComment($ref) , "<br/>";echo "属性列表：<br/>";
printf("%-15s%-10s%-40s<br/>", &#39;Name&#39;, &#39;Access&#39;, &#39;Comment&#39;);$attr = $ref->getProperties();foreach ($attr as $row) {
    printf("%-15s%-10s%-40s<br/>", $row->getName(), getAccess($row), getComment($row));
}echo "常量列表：<br/>";
printf("%-15s%-10s<br/>", &#39;Name&#39;, &#39;Value&#39;);$const = $ref->getConstants();foreach ($const as $key => $val) {
    printf("%-15s%-10s<br/>", $key, $val);
}echo "<br/><br/>";echo "方法列表<br/>";
printf("%-15s%-10s%-30s%-40s<br/>", &#39;Name&#39;, &#39;Access&#39;, &#39;Params&#39;, &#39;Comment&#39;);$methods = $ref->getMethods();foreach ($methods as $row) {
    printf("%-15s%-10s%-30s%-40s<br/>", $row->getName(), getAccess($row), getParams($row), getComment($row));
}// 获取权限function getAccess($method){
    if ($method->isPublic()) {        return &#39;Public&#39;;
    }    if ($method->isProtected()) {        return &#39;Protected&#39;;
    }    if ($method->isPrivate()) {        return &#39;Private&#39;;
    }
}// 获取方法参数信息function getParams($method){
    $str = &#39;&#39;;    $parameters = $method->getParameters();    foreach ($parameters as $row) {        $str .= $row->getName() . &#39;,&#39;;        if ($row->isDefaultValueAvailable()) {            $str .= "Default: {$row->getDefaultValue()}";
        }
    }    return $str ? $str : &#39;&#39;;
}// 获取注释function getComment($var){
    $comment = $var->getDocComment();    // 简单的获取了第一行的信息，这里可以自行扩展
    preg_match(&#39;/\* (.*) *?/&#39;, $comment, $res);    return isset($res[1]) ? $res[1] : &#39;&#39;;
}

Output results:

Student:
属性列表：
Name Access Comment 
id Public 用户ID 
常量列表：
Name Value 
NORMAL 1 FORBIDDEN 2 方法列表
Name Access Params Comment 
getId Public 获取id 
setId Public id,Default: 1

2. Implement MVC architecture

Many frameworks now have MVC architecture, which locates controllers ($controller) and methods ($controller) and methods ( $method), and then use reflection to implement automatic calling.

$class = new ReflectionClass(ucfirst($controller) . 'Controller');$controller = $class->newInstance();if ($class->hasMethod($method)) {    $method = $class->getMethod($method);    $method->invokeArgs($controller, $arguments);
} else {
    throw new Exception("{$controller} controller method {$method} not exists!");
}

3. Implement unit testing

Generally, we will test functions and classes to determine whether they can return results as expected. We can use reflection to implement a simple and universal class. Test cases.

<?phpclass Calc{
    public function plus($a, $b)
    {
        return $a + $b;
    }    public function minus($a, $b)
    {
        return $a - $b;
    }
}function testEqual($method, $assert, $data){
    $arr = explode(&#39;@&#39;, $method);    $class = $arr[0];    $method = $arr[1];    $ref = new ReflectionClass($class);    if ($ref->hasMethod($method)) {        $method = $ref->getMethod($method);        $res = $method->invokeArgs(new $class, $data);        if($res === $assert){            echo "测试结果正确";
        };
    }
}
testEqual(&#39;Calc@plus&#39;, 3, [1, 2]);echo  "<br/>";
testEqual(&#39;Calc@minus&#39;, -1, [1, 2]);

This is the test method of the class, and you can also use reflection to implement the test method of the function.

<?phpfunction title($title, $name){
    return sprintf("%s. %s\r\n", $title, $name);
}$function = new ReflectionFunction(&#39;title&#39;);echo $function->invokeArgs(array(&#39;Dr&#39;, &#39;Phil&#39;));?>

This is just a test case I simply wrote. The PHPUnit unit testing framework relies heavily on the features of Reflection, so you can learn more about it.

4. Cooperate with the DI container to solve dependencies

Many frameworks such as Laravel use Reflection to solve dependency injection problems. For details, you can view the Laravel source code for analysis.
Below our code simply implements a DI container to demonstrate Reflection to solve the dependency injection problem.

<?phpclass DI{
    protected static $data = [];    public function __set($k, $v)
    {
        self::$data[$k] = $v;
    }    public function __get($k)
    {
        return $this->bulid(self::$data[$k]);
    }    // 获取实例
    public function bulid($className)
    {
        // 如果是匿名函数，直接执行，并返回结果
        if ($className instanceof Closure) {            return $className($this);
        }        // 已经是实例化对象的话，直接返回
        if(is_object($className)) {            return $className;
        }        // 如果是类的话，使用反射加载
        $ref = new ReflectionClass($className);        // 监测类是否可实例化
        if (!$ref->isInstantiable()) {            throw new Exception(&#39;class&#39; . $className . &#39; not find&#39;);
        }        // 获取构造函数
        $construtor = $ref->getConstructor();        // 无构造函数，直接实例化返回
        if (is_null($construtor)) {            return new $className;
        }        // 获取构造函数参数
        $params = $construtor->getParameters();        // 解析构造函数
        $dependencies = $this->getDependecies($params);        // 创建新实例
        return $ref->newInstanceArgs($dependencies);
    }    // 分析参数，如果参数中出现依赖类，递归实例化
    public function getDependecies($params)
    {
        $data = [];        foreach($params as $param)
        {            $tmp = $param->getClass();            if (is_null($tmp)) {                $data[] = $this->setDefault($param);
            } else {                $data[] = $this->bulid($tmp->name);
            }
        }        return $data;
    }    // 设置默认值
    public function setDefault($param)
    {
        if ($param->isDefaultValueAvailable()) {            return $param->getDefaultValue();
        }        throw new Exception(&#39;no default value!&#39;);
    }
}class Demo{
    public function __construct(Calc $calc)
    {
        echo $calc->plus(1, 2);
    }
}class Calc{
    public function plus($a, $b)
    {
        return $a + $b;
    }    public function minus($a, $b)
    {
        return $a - $b;
    }
}$di = new DI();$di->calc = &#39;Calc&#39;;  
$di->demo = &#39;Demo&#39;;$di->demo;//输出结果为3

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