Php SPL库 的迭代器类详解【转】

Php-SPL库中的迭代器类详解

SPL提供了多个迭代器类，分别提供了迭代访问、过滤数据、缓存结果、控制分页等功能。，因为php总是在不断壮大，我尽可能列出SPL中所有的迭代类。下面其中一些迭代器类是需要php5.4，另外一些如SearhIteratoer类在最新的php版本中已经去除

1.ArrayIteratoer

从PHP数组创建一个迭代器，当其和IteratorAggregate类一起使用时，免去了直接实现Iterator接口的方法的工作。

<示例>

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$b = array(

'name'=> 'mengzhi',

'age' => '12',

'city'=> 'shanghai'

);

$a = new ArrayIterator($b);

$a->append(array(

'home' => 'china',

'work' => 'developer'

));

$c = $a->getArrayCopy();

print_r($a);

print_r($c);

/**output

ArrayIterator Object

(

[storage:ArrayIterator:private] => Array

(

[name] => mengzhi

[age] => 12

[city] => shanghai

[0] => Array

(

[home] => china

[work] => developer

)

)

)

Array

(

[name] => mengzhi

[age] => 12

[city] => shanghai

[0] => Array

(

[home] => china

[work] => developer

)

)

**/

2. LimitIterator

返回给定数量的结果以及从集合中取出结果的起始索引点：

<示例>

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// Create an iterator to be limited

$fruits = new ArrayIterator(array(

'apple',

'banana',

'cherry',

'damson',

'elderberry'

));

// Loop over first three fruits only

foreach (new LimitIterator($fruits, 0, 3) as$fruit) {

var_dump($fruit);

}

echo"\n";

// Loop from third fruit until the end

// Note: offset starts from zero for apple

foreach (new LimitIterator($fruits, 2) as$fruit) {

print_r($fruit);

}

/**output

string(5) "apple"

string(6) "banana"

string(6) "cherry"

cherrydamsonelderberry

*/

3. AppendIterator

按顺序迭代访问几个不同的迭代器。例如，希望在一次循环中迭代访问两个或者更多的组合。这个迭代器的append方法类似于array_merge()函数来合并数组。

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$array_a = new ArrayIterator(array('a', 'b', 'c'));

$array_b = new ArrayIterator(array('d', 'e', 'f'));

$iterator = new AppendIterator;

$iterator->append($array_a);

$iterator->append($array_b);

foreach ($iteratoras$current) {

echo$current."\n";

}

/**output

a

b

c

d

e

f

*/

4. FilterIterator

基于OuterIterator接口，用于过滤数据，返回符合条件的元素。必须实现一个抽象方法accept()，此方法必须为迭代器的当前项返回true或false

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class UserFilter extends FilterIterator

{

private$userFilter;

publicfunction __construct(Iterator $iterator, $filter)

{

parent::__construct($iterator);

$this->userFilter = $filter;

}

publicfunction accept()

{

$user = $this->getInnerIterator()->current();

if (strcasecmp($user['name'], $this->userFilter) == 0) {

return false;

}

return true;

}

}

$array = array(

array(

'name' => 'Jonathan',

'id' => '5'

),

array(

'name' => 'Abdul',

'id' => '22'

)

);

$object = new ArrayObject($array);

//去除掉名为abdul的人员

$iterator = new UserFilter($object->getIterator(), 'abdul');

foreach ($iteratoras$result) {

echo$result['name'];

}

/**output

Jonathan

**/

5. RegexIterator

继承FilterIterator，支持使用正则表达式模式匹配和修改迭代器中的元素。经常用于将字符串匹配。

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$a = new ArrayIterator(array('test1', 'test2', 'test3'));

$i = new RegexIterator($a, '/^(test)(\d+)/', RegexIterator::REPLACE);

$i->replacement = '$2:$1';

print_r(iterator_to_array($i));

/**output

Array

(

[0] => 1:test

[1] => 2:test

[2] => 3:test

)

**/

6. IteratorIterator

一种通用类型的迭代器，所有实现了Traversable接口的类都可以被它迭代访问。

7. CachingIterator

用来执行提前读取一个元素的迭代操作，例如可以用于确定当前元素是否为最后一个元素。

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$array = array('koala', 'kangaroo', 'wombat', 'wallaby', 'emu', 'kiwi', 'kookaburra', 'platypus');

try {

$object = new CachingIterator(new ArrayIterator($array));

foreach ($objectas$value) {

echo$value;

if ($object->hasNext()) {

echo',';

}

}

}

catch (Exception $e) {

echo$e->getMessage();

}

/**output

koala,kangaroo,wombat,wallaby,emu,kiwi,kookaburra,platypus

**/

8. SeekableIterator

用于创建非顺序访问的迭代器，允许跳转到迭代器中的任何一点上。

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$array = array("apple", "banana", "cherry", "damson", "elderberry");

$iterator = new ArrayIterator($array);

$iterator->seek(3);

echo$iterator->current();

/**output

damson

**/

9. NoRewindIterator

用于不能多次迭代的集合，适用于在迭代过程中执行一次性操作。

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$fruit = array('apple', 'banana', 'cranberry');

$arr = new ArrayObject($fruit);

$it = new NoRewindIterator($arr->getIterator());

echo"Fruit A:\n";

foreach ($itas$item) {

echo$item . "\n";

}

echo"Fruit B:\n";

foreach ($itas$item) {

echo$item . "\n";

}

/**output

Fruit A:

apple

banana

cranberry

Fruit B:

**/

10. EmptyIterator

一种占位符形式的迭代器，不执行任何操作。当要实现某个抽象类的方法并且这个方法需要返回一个迭代器时，可以使用这种迭代器。

11. InfiniteIterator

用于持续地访问数据，当迭代到最后一个元素时，会再次从第一个元素开始迭代访问。

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$arrayit = new ArrayIterator(array('cat', 'dog'));

$infinite = new InfiniteIterator($arrayit);

$limit = new LimitIterator($infinite, 0, 7);

foreach ($limitas$value) {

echo"$value\n";

}

/**output

cat

dog

cat

dog

cat

dog

cat

**/

12. RecursiveArrayIterator

创建一个用于递归形式数组结构的迭代器，类似于多维数组.它为许多更复杂的迭代器提供了所需的操作，如RecursiveTreeIterator和RecursiveIteratorIterator迭代器。

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$fruits = array("a" => "lemon", "b" => "orange", array("a" => "apple", "p" => "pear"));

$iterator = new RecursiveArrayIterator($fruits);

while ($iterator->valid()) {

//检查是否含有子节点

if ($iterator->hasChildren()) {

//输出所以字节点

foreach ($iterator->getChildren() as$key => $value) {

echo$key . ' : ' . $value . "\n";

}

} else {

echo"No children.\n";

}

$iterator->next();

}

/**output

No children.

No children.

a : apple

p : pear

**/

13. RecursiveIteratorIterator

将一个树形结构的迭代器展开为一维结构。

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$fruits = array("a" => "lemon", "b" => "orange", array("a" => "apple", "p" => "pear"));

$arrayiter = new RecursiveArrayIterator($fruits);

$iteriter = new RecursiveIteratorIterator($arrayiter);

foreach ($iteriteras$key => $value) {

$d = $iteriter->getDepth();

echo"depth=$d k=$key v=$value\n";

}

/**output

depth=0 k=a v=lemon

depth=0 k=b v=orange

depth=1 k=a v=apple

depth=1 k=p v=pear

**/

14. RecursiveTreeIterator

以可视在方式显示一个树形结构。

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$hey = array("a" => "lemon", "b" => "orange", array("a" => "apple", "p" => "pear"));

$awesome = new RecursiveTreeIterator(

new RecursiveArrayIterator($hey),

null, null, RecursiveIteratorIterator::LEAVES_ONLY

);

foreach ($awesomeas$line)

echo$line . PHP_EOL;

/**output

|-lemon

|-orange

|-apple

\-pear

**/

15. ParentIterator

是一个扩展的FilterIterator迭代器，它可以过滤掉来自于RecursiveIterator迭代器的非父元素，只找出子节点的键值。通俗来说，就是去枝留叶。

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$hey = array("a" => "lemon", "b" => "orange", array("a" => "apple", "p" => "pear"));

$arrayIterator = new RecursiveArrayIterator($hey);

$it = new ParentIterator($arrayIterator);

print_r(iterator_to_array($it));

/**output

Array

(

[0] => Array

(

[a] => apple

[p] => pear

)

)

**/

16. RecursiveFilterIterator

是FilterIterator迭代器的递归形式，也要求实现抽象的accept()方法，但在这个方法中应该使用$this->getInnerIterator()方法访问当前正在迭代的迭代器。

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class TestsOnlyFilter extends RecursiveFilterIterator

{

publicfunction accept()

{

// 找出含有“叶”的元素

return$this->hasChildren() || (mb_strpos($this->current(), "叶") !== FALSE);

}

}

$array = array("叶1", array("李2", "叶3", "叶4"), "叶5");

$iterator = new RecursiveArrayIterator($array);

$filter = new TestsOnlyFilter($iterator);

$filter = new RecursiveIteratorIterator($filter);

print_r(iterator_to_array($filter));

/**output

Array

(

[0] => 叶1

[1] => 叶3

[2] => 叶5

)

**/

17. RecursiveRegexIterator

是RegexIterator迭代器的递归形式，只接受RecursiveIterator迭代器作为迭代对象。

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$rArrayIterator = new RecursiveArrayIterator(array('叶1', array('tet3', '叶4', '叶5')));

$rRegexIterator = new RecursiveRegexIterator($rArrayIterator, '/^叶/',

RecursiveRegexIterator::ALL_MATCHES);

foreach ($rRegexIteratoras$key1 => $value1) {

if ($rRegexIterator->hasChildren()) {

// print all children

echo"Children: ";

foreach ($rRegexIterator->getChildren() as$key => $value) {

echo$value . " ";

}

echo"\n";

} else {

echo"No children\n";

}

}

/**output

No children

Children: 叶4 叶5

**/

18. RecursiveCachingIterator

在RecursiveIterator迭代器上执行提前读取一个元素的递归操作。

19. CallbackFilterIterator(PHP5.4)

同时执行过滤和回调操作，在找到一个匹配的元素之后会调用回调函数。

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$hey = array( "李1", "叶2", "叶3", "叶4", "叶5", "叶6",);

$arrayIterator = new RecursiveArrayIterator($hey);

function isYe($current)

{

return mb_strpos($current,'叶') !== false;

}

$rs = new CallbackFilterIterator($arrayIterator, 'isYe');

print_r(iterator_to_array($rs));

/**output

Array

(

[0] => 叶2

[1] => 叶3

[2] => 叶4

[3] => 叶5

[4] => 叶6

)

**/

20. DirectoryIterator

目录文件遍历器

方 法	描 述
DirectoryIterator::getSize	得到文件大小
DirectoryIterator::getType	得到文件类型
DirectoryIterator::isDir	如果当前项是一个目录，返回true
DirectoryIterator::isDot	如果当前项是.或..，返回true
DirectoryIterator::isExecutable	如果文件可执行，返回true
DirectoryIterator::isFile	如果文件是一个常规文件，返回true
DirectoryIterator::isLink	如果文件是一个符号链接，返回true
DirectoryIterator::isReadable	如果文件可读，返回true
DirectoryIterator::isWritable	如果文件可写，返回true
DirectoryIterator::key	返回当前目录项
DirectoryIterator::next	移动到下一项
DirectoryIterator::rewind	将目录指针返回到开始位置
DirectoryIterator::valid	检查目录中是否包含更多项

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$it = new DirectoryIterator("../");

foreach ($itas$file) {

//用isDot ()方法分别过滤掉“.”和“..”目录

if (!$it->isDot()) {

echo$file . "\n";

}

}

21. RecursiveDirectoryIterator

递归目录文件遍历器，可实现列出所有目录层次结构，而不是只操作一个目录。

方 法	描 述
RecursiveDirectoryIterator::getChildren	如果这是一个目录，为当前项返回一个迭代器
RecursiveDirectoryIterator::hasChildren	返回当前项是否是一个目录而不是.或..
RecursiveDirectoryIterator::key	返回当前目录项的路径和文件名
RecursiveDirectoryIterator::next	移动到下一项
RecursiveDirectoryIterator::rewind	将目录指针返回到开始位置
RecursiveIteratorIterator::current	访问当前元素值
RecursiveIteratorIterator::getDepth	得到递归迭代的当前深度
RecursiveIteratorIterator::getSubIterator	得到当前活动子迭代器
RecursiveIteratorIterator::key	访问当前键
RecursiveIteratorIterator::next	前移到下一个元素
RecursiveIteratorIterator::rewind	将迭代器返回到顶级内层迭代器的第一个元素
RecursiveIteratorIterator::valid	检查当前位置是否合法

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//列出指定目录中所有文件

$path = realpath('../');

$objects = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($path), RecursiveIteratorIterator::SELF_FIRST);

foreach ($objectsas$name => $object) {

echo"$name\n";

}

22. FilesystemIterator

是DirectoryIterator的遍历器

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$it = new FilesystemIterator('../');

foreach ($itas$fileinfo) {

echo$fileinfo->getFilename() . "\n";

}

23. GlobIterator

带匹配模式的文件遍历器

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//找出../目录中.php扩展名的文件

$iterator = new GlobIterator('./*.php');

if (!$iterator->count()) {

echo'无php文件';

} else {

$n = 0;

printf("总计 %d 个php文件\r\n", $iterator->count());

foreach ($iteratoras$item) {

printf("[%d] %s\r\n", ++$n, $iterator->key());

}

}

/**output

总计 23 个php文件

[1] .\1.php

[2] .\11.php

[3] .\12.php

[4] .\13.php

[5] .\14.php

[6] .\15.php

[7] .\16.php

[8] .\17.php

[9] .\19.php

[10] .\2.php

[11] .\20.php

[12] .\21.php

[13] .\22.php

[14] .\23.php

[15] .\24.php

[16] .\25.php

[17] .\26.php

[18] .\3.php

[19] .\4.php

[20] .\5.php

[21] .\7.php

[22] .\8.php

[23] .\9.php

**/

24. MultipleIterator

用于迭代器的连接器，具体看示例

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$person_id = new ArrayIterator(array('001', '002', '003'));

$person_name = new ArrayIterator(array('张三', '李四', '王五'));

$person_age = new ArrayIterator(array(22, 23, 11));

$mit = new MultipleIterator(MultipleIterator::MIT_KEYS_ASSOC);

$mit->attachIterator($person_id, "ID");

$mit->attachIterator($person_name, "NAME");

$mit->attachIterator($person_age, "AGE");

echo"连接的迭代器个数:".$mit->countIterators() . "\n"; //3

foreach ($mitas$person) {

print_r($person);

}

/**output

Array

(

[ID] => 001

[NAME] => 张三

[AGE] => 22

)

Array

(

[ID] => 002

[NAME] => 李四

[AGE] => 23

)

Array

(

[ID] => 003

[NAME] => 王五

[AGE] => 11

)

**/

25. RecursiveCallbackFilterIterator(PHP5.4)

在RecursiveIterator迭代器上进行递归操作，同时执行过滤和回调操作，在找到一个匹配的元素之后会调用回调函数。

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function doesntStartWithLetterT($current)

{

$rs = $current->getFileName();

return$rs[0] !== 'T';

}

$rdi = new RecursiveDirectoryIterator(__DIR__);

$files = new RecursiveCallbackFilterIterator($rdi, 'doesntStartWithLetterT');

foreach (new RecursiveIteratorIterator($files) as$file) {

echo$file->getPathname() . PHP_EOL;

}

26. SimpleXMLIterator

XMl文档访问迭代器，可实现访问xml中所有节点

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$xml = <<<XML

<books>

<book>

<title>PHP Basics</title>

<author>Jim Smith</author>

</book>

<book>XML basics</book>

</books>

XML;

// SimpleXML转换为数组

function sxiToArray($sxi)

{

$a = array();

for ($sxi->rewind(); $sxi->valid(); $sxi->next()) {

if (!array_key_exists($sxi->key(), $a)) {

$a[$sxi->key()] = array();

}

if ($sxi->hasChildren()) {

$a[$sxi->key()][] = sxiToArray($sxi->current());

} else {

$a[$sxi->key()][] = strval($sxi->current());

}

}

return$a;

}

$xmlIterator = new SimpleXMLIterator($xml);

$rs = sxiToArray($xmlIterator);

print_r($rs);

/**output

Array

(

[book] => Array

(

[0] => Array

(

[title] => Array

(

[0] => PHP Basics

)

[author] => Array

(

[0] => Jim Smith

)

)

[1] => XML basics

)

)

**/

转：/article/2345828.html