SPL的基本使用

SPL是Standard PHP Library（PHP标准库）的缩写。

根据官方定义，它是"a collection of interfaces and classes that are meant to solve standard problems"。但是，目前在使用中，SPL更多地被看作是一种使object（物体）模仿array（数组）行为的interfaces和classes。

这几天学习SPL，这是我写的一点小笔记，望日后再次使用时能够想起点滴，SPL核心便是Iterator，熟练使用Iterator可以让我们更加方便的去操作数据.

ArrayIterator迭代器示例

<?php
$fruits = array
(
    "apple" => 'apple value',
    "orange" => 'orange value',
    "grape" => "grape value",
    "plum" => "plum value"
);
print_r($fruits);
echo "**** use fruits directly
";
foreach ($fruits as $key => $value)
{
    echo $key . ":" . $value . "
";
}
//使用ArrayIterator遍历数组
$obj = new ArrayObject($fruits);
$it = $obj->getIterator();

echo "***** use ArrayIterator in for
";
foreach ($it as $key => $value)
{
    echo $key . ":" . $value . "
";
}

echo "***** use ArrayIterator in while
";
$it->rewind();//调用current之前要用rewind
while ($it->valid())
{
    echo $it->key() . ":" . $it->current()."
";
    $it->next();
}
//跳过某些元素进行打印
echo "***** use seek before while
";
$it->rewind();
if ($it->valid())
{
    $it->seek(1);
    while($it->valid())
    {
        echo $it->key() . ":" . $it->current()."
";
        $it->next();
    }
}

echo "***** use ksort
";
$it->ksort();
foreach ($it as $key => $value)
{
    echo $key . ":" . $value . "
";
}

echo "***** use asort
";
$it->asort();
foreach ($it as $key => $value)
{
    echo $key . ":" . $value . "
";
}

AppendIterator迭代器示例

<?php
$array_a = new ArrayIterator(array('a','b','c'));
$array_b = new ArrayIterator(array('d','e','f'));
$it = new AppendIterator();
$it->append($array_a);
//通过append方法把迭代器对象添加到AppendIterator对象中
$it->append($array_b);
foreach ($it as $key => $value)
{
    echo $value."
";
}

MultipleIterator迭代器示例

<?php
$idIter = new ArrayIterator(array('01','02','03'));
$nameIter = new ArrayIterator(array('张三','李四','王五'));
$ageIter = new ArrayIterator(array('22','23','25'));
$mit = new MultipleIterator(MultipleIterator::MIT_KEYS_ASSOC);
$mit->attachIterator($idIter,"ID");
$mit->attachIterator($nameIter,"NAME");
$mit->attachIterator($ageIter,"AGE");
foreach ($mit as $value)
{
    print_r($value);
}

FilesystemIterator迭代器示例

<?php
$it = new FilesystemIterator('.');
foreach ($it as $finfo)
{
    printf("%s	%s	%8s	%s
",
    date("Y-m-d H:i:s",$finfo->getMTime()),
    $finfo->isDir()?"<DIR>":"",
    number_format($finfo->getSize()),
    $finfo->getFileName()
    );
}

Countable接口示例

<?php
class CountMe implements Countable
{
    protected $_myCount = 3;
    public function count()
    {
        return $this->_myCount;
    }
}
$obj = new CountMe();
echo count($obj);

OuterIterator接口示例

<?php
$array = ['Value1','Value2','Value3','Value4'];
$outerObj = new OuterImpl(new ArrayIterator($array));

foreach ($outerObj as $key => $value)
{
    echo "++" . $key . " - " . $value . "
";
}

class OuterImpl extends IteratorIterator
{
    public function current()
    {
        return parent::current()."_tail";
    }
    public function key()
    {
        return "Pre_".parent::key();
    }
}

autoload机制的三种用法

<?php
//设置autoload寻找php定义的类文件的扩展名,多个扩展名用逗号分隔,前面的扩展名优先被匹配
spl_autoload_extensions('.class.php,.php');
//设置autoload寻找php定义的类文件的目录,多个目录用PATH_SEPARATOR进行分隔
set_include_path(get_include_path().PATH_SEPARATOR."libs/");
//提示PHP使用Autoload机制查找类定义
spl_autoload_register();
new Test();

<?php
//定义__autoload函数,可以在不调用spl_autoload_register函数的情况完成类的装载
function __autoload($class_name)
{
    echo "__autoload class:".$class_name."
";
    require_once ($class_name.'.php');
}
//定义一个替换__autoload函数的类文件装载函数
function classLoader($class_name)
{
    echo "classLoader() load class:".$class_name."
";
    require_once ($class_name.'.php');
}
//传入定义好的装载类的函数名称替换__autoload
spl_autoload_register('classLoader');
new Test();

<?php

//定义一个替换__autoload函数的类文件装载函数
function classLoader($class_name)
{
    echo "classLoader() load class:".$class_name."
";
    set_include_path(".");
    spl_autoload($class_name);//当我们不用require或者requir_once载入类文件的时候,而想通过系统查找include_path来装载类是,必须显式调用spl_autoload函数,参数是类的名称来重启类文件的自动查找(装载)
}
//传入定义好的装载类的函数名称替换__autoload
spl_autoload_register('classLoader');
new Test();