PHP面向对象中的重要知识点(三)_PHP教程
时间：2021-07-01 10:21:17
帮助过：5人阅读
1. namespace:
和C++中的名字空间很像，作用也一样，都是为了避免在引用较多第三方库时而带来的名字冲突问题。通过名字空间，即便两个class的名称相同，但是因为位于不同的名字空间内，他们仍然可以被精确定位和区分。第一次看到PHP的名字空间语法时，感觉和C++相比在语法上是非常非常相似的，然而在写点儿小例子做做实验的时候才发现，他们的差别还是很大的，为了避免以后忘记，所以这里特别将其记录了下来。见如下代码：
getName();
if ($c->isUserDefined()) {
$details .= "$name is user defined.\n";
}
if ($c->isInternal()) {
$details .= "$name is built-in.\n";
}
if ($c->isAbstract()) {
$details .= "$name is abstract class.\n";
}
if ($c->isFinal()) {
$details .= "$name is final class.\n";
}
if ($c->isInstantiable()) {
$details .= "$name can be instantiated.\n";
} else {
$details .= "$name cannot be instantiated.\n";
}
return $details;
}
function classSource(ReflectionClass $c) {
$path = $c->getFileName();
$lines = @file($path);
//获取类定义代码的起始行和截至行。
$from = $c->getStartLine();
$to = $c->getEndLine();
$len = $to - $from + 1;
return implode(array_slice($lines,$from - 1,$len));
}
print "The following is Class Information.\n";
print classInfo(new ReflectionClass('TestClass'));
print "\nThe following is Class Source.\n";
print classSource(new ReflectionClass('TestClass'));
运行结果如下：
bogon:TestPhp$ php reflection_test.php
The following is Class Information.
TestClass is user defined.
TestClass can be instantiated.
The following is Class Source.
class TestClass {
public $publicVariable;
function publicMethod() {
print "This is publicMethod.\n";
}
}
下面让我们仍然以代码示例和关键性注释的方法继续ReflectionMethod的学习之旅。
getName();
$details = "";
if ($m->isUserDefined()) {
$details .= "$name is user defined.\n";
}
if ($m->isInternal()) {
$details .= "$name is built-in.\n";
}
if ($m->isAbstract()) {
$details .= "$name is abstract.\n";
}
if ($m->isPublic()) {
$details .= "$name is public.\n";
}
if ($m->isProtected()) {
$details .= "$name is protected.\n";
}
if ($m->isPrivate()) {
$details .= "$name is private.\n";
}
if ($m->isStatic()) {
$details .= "$name is static.\n";
}
if ($m->isFinal()) {
$details .= "$name is final.\n";
}
if ($m->isConstructor()) {
$details .= "$name is constructor.\n";
}
if ($m->returnsReference()) {
$details .= "$name returns a reference.\n";
}
return $details;
}
function methodSource(ReflectionMethod $m) {
$path = $m->getFileName();
$lines = @file($path);
$from = $m->getStartLine();
$to = $m->getEndLine();
$len = $to - $from + 1;
return implode(array_slice($lines, $from - 1, $len));
}
$rc = new ReflectionClass('TestClass');
$methods = $rc->getMethods();
print "The following is method information.\n";
foreach ($methods as $method) {
print methodInfo($method);
print "\n--------------------\n";
}
print "The following is Method[TestClass::publicMethod] source.\n";
print methodSource($rc->getMethod('publicMethod'));
运行结果如下：
bogon:TestPhp$ php reflection_test.php
The following is method information.
__construct is user defined.
__construct is public.
__construct is constructor.
--------------------
privateMethod is user defined.
privateMethod is private.
--------------------
publicMethod is user defined.
publicMethod is public.
--------------------
publicMethod2 is user defined.
publicMethod2 is public.
--------------------
The following is Method[TestClass::publicMethod] source.
function publicMethod() {
print "This is publicMethod.\n";
}
让我们继续ReflectionParameter吧，他表示的是成员函数的参数信息。继续看代码吧。
getDeclaringClass();
$name = $p->getName();
$class = $p->getClass();
$position = $p->getPosition();
$details .= "\$$name has position $position.\n";
if (!empty($class)) {
$classname = $class->getName();
$details .= "\$$name must be a $classname object\n";
}
if ($p->isPassedByReference()) {
$details .= "\$$name is passed by reference.\n";
}
if ($p->isDefaultValueAvailable()) {
$def = $p->getDefaultValue();
$details .= "\$$name has default: $def\n";
}
return $details;
}
$rc = new ReflectionClass('TestClass');
$method = $rc->getMethod('publicMethod2');
$params = $method->getParameters();
foreach ($params as $p) {
print paramInfo($p)."\n";
}
运行结果如下：
bogon:TestPhp$ php reflection_test.php
$arg1 has position 0.
$arg1 must be a ParamClass object
$arg2 has position 1.
$arg2 is passed by reference.
$arg3 has position 2.
$arg3 has default:
上面介绍的都是通过PHP提供的Reflection API来遍历任意class的具体信息，事实上和Java等其他语言提供的反射功能一样，PHP也同样支持通过反射类调用实际对象的方法，这里将主要应用到两个方法，分别是ReflectionClass::newInstance()来创建对象实例，另一个是ReflectionMethod::invoke()，根据对象实例和方法名执行该方法。见如下代码：
privateArg = $arg;
}
function publicMethod() {
print '$privateArg = '.$this->privateArg."\n";
}
function publicMethod2($arg1, $arg2) {
print '$arg1 = '.$arg1.' $arg2 = '.$arg2."\n";
}
}
$rc = new ReflectionClass('TestClass');
$testObj = $rc->newInstanceArgs(array('This is private argument.'));
$method = $rc->getMethod('publicMethod');
$method->invoke($testObj);
$method2 = $rc->getMethod('publicMethod2');
$method2->invoke($testObj,"hello","world");
运行结果如下：
bogon:TestPhp$ php reflection_test.php
$privateArg = This is private argument.
$arg1 = hello $arg2 = world
事实上ReflectionClass、ReflectionMethod和ReflectionParameter提供给我们的可用方法还有更多，这里只是给出几个最典型的方法，以便我们可以更为直观的学习和了解PHP Reflection API。相信再看完以后的代码示例之后，我们都会比较清楚，如果今后需要用到和class相关的功能，就从ReflectionClass中查找，而member function的信息则一定来自于ReflectionMethod，方法参数信息来自于ReflectionParameter。
注：该Blog中记录的知识点，是在我学习PHP的过程中，遇到的一些PHP和其他面向对象语言相比比较独特的地方，或者是对我本人而言确实需要簿记下来以备后查的知识点。虽然谈不上什么深度，但是还是希望能与大家分享。
http://www.bkjia.com/PHPjc/664271.htmlwww.bkjia.comtruehttp://www.bkjia.com/PHPjc/664271.htmlTechArticle1. namespace: 和C++中的名字空间很像，作用也一样，都是为了避免在引用较多第三方库时而带来的名字冲突问题。通过名字空间，即便两个cl...
