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>
$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>
// 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。
$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$current."\n"; }
/**output
a
b
c
d
e
f
*/
4. FilterIterator
基于OuterIterator接口,用于过滤数据,返回符合条件的元素。必须实现一个抽象方法accept(),此方法必须为迭代器的当前项返回true或false
class UserFilter extends FilterIterator { private$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。
$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。
$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。
$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。
$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。
$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。
$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。
$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。
$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。
$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。
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。
$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。
$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
$it = new DirectoryIterator("../"); foreach ($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
//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. Filesyste
mIterator
是DirectoryIterator的遍历器
$it = new FilesystemIterator('../'); foreach ($itas$fileinfo) { echo$fileinfo->getFilename() . "\n"; }
23. GlobIterator
带匹配模式的文件遍历器
//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()); } } /**outpu
t
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
$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); } /**outp
ut
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。
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
$xml = <<<XML
<books>
<book>
<title>PHP Basics</title>
<author>Jim Smith</author>
</book>
<book>XML basics</book>
</books>
XML;
// SimpleXML转换为数组 function sxiToArray($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
)
)
**/