PHP spl_autoload和class_exsits使用技能

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."
";

    if (file_exists($realPath)) {

        if(!class_exists($className,false)){
            $ret = include($realPath);
            print "spl_autoload_  autoload:$className is loaded : result = $ret 
";
        }
        else
            print "spl_autoload_ autoload:$className is already loaded
";

    }
});

ChildrenClass.php:

<?php
namespace CORE;
use COREParentClass;
/**
 * 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 COREParentClass;
use COREChildrenClass;

print "Section01------------------------

";



print "
Section02------------------------

";

$instance01 = new ChildrenClass('aa','vv');
$instance02 = new ParentClass('bb','uu');

print "
Section03------------------------

";
print "Class Load Test-----------------------
";

if(!class_exists('ChildrenClass')){
    print "
************
Warning : in Section 03 : 
Class ChildrenClass is not loaded
";
}

$interfaces = class_implements("ParentClass");

print_r($interfaces);
if(isset($interfaces['ParentClass'])){
    print "OK,PASS";
}
else{
    print "NO,IT'S NOT";
}


print "
Section04------------------------

";
if(!class_exists('ChildrenClass')){
    print "
************
TEST : in Section 04 : 
Class ChildrenClass is not loaded
";
}

$rc =  new ReflectionClass('ChildrenClass');
try {
    if($rc->implementsInterface('ParentClass')){
        print 'imples';
    }
    print 'parent class:' . $rc->getParentClass();
}catch(ReflectionException $e){

}

然后输出结果是：

J:xamppphpphp.exe E:phpStormWorksphp01	estindex.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:phpStormWorksphp01	estindex.php on line 29

Call Stack:
    0.0008     131888   1. {main}() E:phpStormWorksphp01	estindex.php:0
    0.0042     147400   2. class_implements() E:phpStormWorksphp01	estindex.php:29

NO,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:phpStormWorksphp01	estindex.php on line 46

ReflectionException: Class ChildrenClass does not exist in E:phpStormWorksphp01	estindex.php on line 46

Call Stack:
    0.0008     131888   1. {main}() E:phpStormWorksphp01	estindex.php:0
    0.0079     147816   2. ReflectionClass->__construct() E:phpStormWorksphp01	estindex.php:46


Process finished with exit code 255

总结：
class_implements()
ReflectionClass()
class_exists()
$interfaces = class_implements(‘CORETestImpl’);
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(‘COREParentClass’)
$interfaces[‘COREInterf’]
namespace前面的无所谓
但是interfaces[‘COREInterf’] 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 NAMESPACEXXXXClass 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 COREChildrenClass, because the name is already in use in E:phpStormWorksphp01coreChildrenClass.php on line 29
PHP Stack trace:
PHP 1. {main}() E:phpStormWorksphp01 estindex.php:0
PHP 2. class_implements() E:phpStormWorksphp01 estindex.php:93
PHP 3. spl_autoload_call() E:phpStormWorksphp01 estindex.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."
";


    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 class
        print "spl_autoload_  preCheck:$className | $classId | is already loaded
";
    }


    if (file_exists($realPath)) {

        if(class_exists($className,false)||interface_exists($className,false)){

            print "spl_autoload_  autoload:$className | $classId | is already loaded
";
        }
        else{
            print "spl_autoload_  autoload: try to load $className | $classId |
";
            if ( false ===  include($realPath))
                print "spl_autoload_  autoload:$className | $classId | failed to be loaded
";
            else
                print "spl_autoload_  autoload:$className | $classId | is loaded
";
        }


    }
});