PHP spl_autoload和class_exsits使用技能

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本文章的PHP使用版本:5.4.7

PHP建议使用：
spl_autoload_register
那么写了一种实现

文件路径

core
- core.php
- ChildrenClass.php
- ParentClass.php
test
- index.php

core.php:


<?php/*** Created by PhpStorm.* User: http://blog.csdn.net/cor_twi* Date: 2016/02/25* Time: 11:23*/spl_autoload_register(function ($classId)
{$dirname            = dirname(__FILE__);$classIdParts       = explode("\\", $classId);$classIdLength      = count($classIdParts);$className          = ($classIdParts[$classIdLength - 1]);$defaultNameSpace   = substr(strrchr($dirname,"\\"),1); $namespace          = $classIdLength==1? $defaultNameSpace : $classIdParts[0];for ($i = 1; $i < $classIdLength-1; $i++) {$namespace .= '/' . $classIdParts[$i];}$path = dirname(__FILE__) . "/../" . $namespace . "/" . $className . '.php';$realPath = realpath($path);#print "autoload:realPath:" .  $realPath."\n";if (file_exists($realPath)) {if(!class_exists($className,false)){$ret = include($realPath);print "spl_autoload_  autoload:$className is loaded : result = $ret \n";}elseprint "spl_autoload_ autoload:$className is already loaded\n";}
});

ChildrenClass.php:

<?php
namespace CORE;
use CORE\ParentClass;
/*** Created by PhpStorm.* User: http://blog.csdn.net/cor_twi* Date: 2016/02/22* Time: 9:55*/
class ChildrenClass extends ParentClass
{private $varPro_;public  function __construct($var01,$var02){parent::__construct($var01,$var02);$this->varPro_ = "ChildrenClass";}}

ParentClass.php:

<?php/*** Created by PhpStorm.* User: http://blog.csdn.net/cor_twi* Date: 2016/02/22* Time: 9:40*/
namespace CORE;
class ParentClass
{public static $variable01;public static $variable02;protected  $varPro;/***constructor*/public function __construct($var1,$var2){self::$variable01 = $var1;self::$variable02 = $var2;$this->varPro = "ParentClass";}
}

index.php:

<?php
/*** Created by PhpStorm.* User: http://blog.csdn.net/cor_twi* Date: 2016/03/05* Time: 16:06*/
require('../core/core.php');use CORE\ParentClass;
use CORE\ChildrenClass;print "Section01------------------------\n\n";print "\nSection02------------------------\n\n";$instance01 = new ChildrenClass('aa','vv');
$instance02 = new ParentClass('bb','uu');print "\nSection03------------------------\n\n";
print "Class Load Test-----------------------\n";if(!class_exists('ChildrenClass')){print "\n************\nWarning : in Section 03 : \nClass ChildrenClass is not loaded\n";
}$interfaces = class_implements("ParentClass");print_r($interfaces);
if(isset($interfaces['ParentClass'])){print "OK,PASS";
}
else{print "NO,IT'S NOT";
}print "\nSection04------------------------\n\n";
if(!class_exists('ChildrenClass')){print "\n************\nTEST : in Section 04 : \nClass ChildrenClass is not loaded\n";
}$rc =  new ReflectionClass('ChildrenClass');
try {if($rc->implementsInterface('ParentClass')){print 'imples';}print 'parent class:' . $rc->getParentClass();
}catch(ReflectionException $e){}

然后输出结果是：

J:\xampp\php\php.exe E:\phpStormWorks\php01\test\index.php
Section01------------------------Section02------------------------spl_autoload_  autoload:ParentClass is loaded : result = 1 
spl_autoload_  autoload:ChildrenClass is loaded : result = 1 Section03------------------------Class Load Test-----------------------************
Warning : in Section 03 : 
Class ChildrenClass is not loaded
spl_autoload_  autoload:ParentClass is loaded : result = 1 Warning: class_implements(): Class ParentClass does not exist and could not be loaded in E:\phpStormWorks\php01\test\index.php on line 29Call Stack:0.0008     131888   1. {main}() E:\phpStormWorks\php01\test\index.php:00.0042     147400   2. class_implements() E:\phpStormWorks\php01\test\index.php:29NO,IT'S NOT
Section04------------------------************
TEST : in Section 04 : 
Class ChildrenClass is not loaded
spl_autoload_  autoload:ChildrenClass is loaded : result = 1 Fatal error: Uncaught exception 'ReflectionException' with message 'Class ChildrenClass does not exist' in E:\phpStormWorks\php01\test\index.php on line 46ReflectionException: Class ChildrenClass does not exist in E:\phpStormWorks\php01\test\index.php on line 46Call Stack:0.0008     131888   1. {main}() E:\phpStormWorks\php01\test\index.php:00.0079     147816   2. ReflectionClass->__construct() E:\phpStormWorks\php01\test\index.php:46Process finished with exit code 255

总结：
class_implements()
ReflectionClass()
class_exists()
$interfaces = class_implements(‘\CORE\TestImpl’);
对于当前版本来说：
这几个类的名字必须写use 的短语 as 的也不行：
例如：class_exists(‘\CORE\ParentClass’)
$interfaces[‘CORE\Interf’]
namespace前面的\无所谓
但是interfaces[‘CORE\Interf’] 前面的\有所谓！！！

总结

对于写了namespace的类文件来说,你有两个选择
要么use namespace要么new 和 instanceof 的时候使用namespace，否则出现Fatal error: Class ‘TestImpl’ not found in 即便它正确触发spl_autoload。【原因见后面<Reason>】
要么用namespace前缀来使用这个类符号

如果没有写namespace的呢
没有写namespace的类文件，可以随意使用他的类名字，自动触发spl_autoload注册的函数。
对于类或者接口，class_exsits()和interface_exsits()都如果有他们有namespace需要使用它才能返回正确的结果。
对于class_implements()、ReflectionClass()和implementsInterface()，如果类或者接口具有namespace必须使用带namespace的名称符号来作为参数，否则你将看到：Fatal error: Cannot redeclare class NAMESPACE\XXXXClass in
原因未知：是个bug，经过测试PHP7也有这个问题PHP或许不承认他是个BUG。而且加载器无法检查出来已经被加载。如果你改成class_implements(‘XXXXClass’,false);那么就是[PHP 5.4.7]Warning: class_implements(): Class ChildrenClass does not exist in (即使你写了use)

PHP7:的报错是
PHP Fatal error: Cannot declare class CORE\ChildrenClass, because the name is already in use in E:\phpStormWorks\php01\core\ChildrenClass.php on line 29
PHP Stack trace:
PHP 1. {main}() E:\phpStormWorks\php01\test\index.php:0
PHP 2. class_implements() E:\phpStormWorks\php01\test\index.php:93
PHP 3. spl_autoload_call() E:\phpStormWorks\php01\test\index.php:93

<Reason>：由现象倒推而来，所有的PHP版本，对于有namespace的类或者接口，它是以带namespace的形式autoload的，不管你写不写use

如果用include_once()，那么不在本文研究范围之内

写的时候手贱文章弄没有了一次，重写之。
测试结论仅供参考。
附上spl_autoload_实现：

<?php/*** Created by PhpStorm.* User: http://blog.csdn.net/cor_twi* Date: 2016/02/25* Time: 11:23*/spl_autoload_register(function ($classId)
{$dirname            = dirname(__FILE__);$classIdParts       = explode("\\", $classId);$classIdLength      = count($classIdParts);$className          = ($classIdParts[$classIdLength - 1]);$defaultNameSpace   = substr(strrchr($dirname,"\\"),1); //here is core$namespace          = $classIdLength==1? $defaultNameSpace : $classIdParts[0];for ($i = 1; $i < $classIdLength-1; $i++) {$namespace .= '/' . $classIdParts[$i];}$path = dirname(__FILE__) . "/../" . $namespace . "/" . $className . '.php';$realPath = realpath($path);#print "autoload:realPath:" .  $realPath."\n";if(class_exists($classId,false)||interface_exists($classId,false)){
//如果代码能进来这个函数说明没有被加载，便不会执行到这里，无法阻止Fatal error: Cannot redeclare classprint "spl_autoload_  preCheck:$className | $classId | is already loaded\n";}if (file_exists($realPath)) {if(class_exists($className,false)||interface_exists($className,false)){print "spl_autoload_  autoload:$className | $classId | is already loaded\n";}else{print "spl_autoload_  autoload: try to load $className | $classId |\n";if ( false ===  include($realPath))print "spl_autoload_  autoload:$className | $classId | failed to be loaded\n";elseprint "spl_autoload_  autoload:$className | $classId | is loaded\n";}}
});