一个简短的例子:

<?php

$test_array = array (
  'bla' => 'blub',
  'foo' => 'bar',
  'another_array' => array (
    'stack' => 'overflow',
  ),
);
$xml = new SimpleXMLElement('<root/>');
array_walk_recursive($test_array, array ($xml, 'addChild'));
print $xml->asXML();

结果

<?xml version="1.0"?>
<root>
  <blub>bla</blub>
  <bar>foo</bar>
  <overflow>stack</overflow>
</root>

键和值会被交换——你可以在array_walk之前用array_flip()来修复这个问题。array_walk_recursive需要PHP 5。你可以用array_walk代替，但你不会得到'stack' => 'overflow'在XML中。

function toXML($data, $obj = false, $dom) {
    $is_first_level = false;
    if($obj === false) {
        $dom = new DomDocument('1.0');
        $obj = $dom;
        $is_first_level = true;
    }

    if(is_array($data)) {
        foreach($data as $key => $item) {
            $this->toXML($item, $obj->appendChild($dom->createElement($key)), $dom);
        }
    }else {
        $obj->appendChild($dom->createTextNode($data));
    }

    if($is_first_level) {
        $obj->formatOutput = true;
        return $obj->saveXML();
    }
    return $obj;
}

你可以使用胡子模板引擎，并制作一个模板，如:

{{#RECEIVER}}
<RECEIVER>
    <COMPANY>{{{COMPANY}}}</COMPANY>
    <CONTACT>{{{CONTACT}}}</CONTACT>
    <ADDRESS>{{{ADDRESS}}}</ADDRESS>
    <ZIP>{{ZIP}}</ZIP>
    <CITY>{{{CITY}}}</CITY>
</RECEIVER>
{{/RECEIVER}}
{{#DOC}}
<DOC>
    <TEXT>{{{TEXT}}}</TEXT>
    <NUMBER>{{{NUMBER}}}</NUMBER>
</DOC>
{{/DOC}}

在PHP中这样使用它:

require_once( __DIR__ .'/../controls/Mustache/Autoloader.php' );
Mustache_Autoloader::register();
$oMustache = new Mustache_Engine();
$sTemplate = implode( '', file( __DIR__ ."/xml.tpl" ));
$return = $oMustache->render($sTemplate, $res);
echo($return);

整个XML结构定义在$data数组中:

function array2Xml($data, $xml = null)
{
    if (is_null($xml)) {
        $xml = simplexml_load_string('<' . key($data) . '/>');
        $data = current($data);
        $return = true;
    }
    if (is_array($data)) {
        foreach ($data as $name => $value) {
            array2Xml($value, is_numeric($name) ? $xml : $xml->addChild($name));
        }
    } else {
        $xml->{0} = $data;
    }
    if (!empty($return)) {
        return $xml->asXML();
    }
}

function array2xml(array $data, SimpleXMLElement $object = null, $oldNodeName = 'item')
{
    if (is_null($object)) $object = new SimpleXMLElement('<root/>');
    $isNumbered = true;
    $idx = 0;
    foreach ($data as $key => $x)
        if (is_string($key) || ($idx++ != $key + 0))
            $isNumbered = false;
    foreach ($data as $key => $value)
    {   
        $attribute = preg_match('/^[0-9]/', $key . '') ? $key : null;
        $key = (is_string($key) && !preg_match('/^[0-9]/', $key . '')) ? $key : preg_replace('/s$/', '', $oldNodeName);
        if (is_array($value))
        {
            $new_object = $object->addChild($key);
            if (!$isNumbered && !is_null($attribute)) $new_object->addAttribute('id', $attribute);
            array2xml($value, $new_object, $key);
        }
        else
        {
            if (is_bool($value)) $value = $value ? 'true' : 'false';
            $node = $object->addChild($key, htmlspecialchars($value));
            if (!$isNumbered && !is_null($attribute) && !isset($node->attributes()->id))
                $node->addAttribute('id', $attribute);
        }
    }
    return $object;
}

例如，该函数返回一个<obj>…</obj><obj>…</obj>数值索引的XML标记。

输入:

    array(
    'people' => array(
        'dog',
        'cat',
        'life' => array(
            'gum',
            'shoe',
        ),
        'fish',
    ),
    array('yeah'),
)

输出:

<root>
    <people>
        <people>dog</people>
        <people>cat</people>
        <life>
            <life>gum</life>
            <life>shoe</life>
        </life>
        <people>fish</people>
        <people>
            <people>yeah</people>
        </people>
    </people>
</root>

这应该能满足所有的共同需求。也许你可以把第三行改成:

$key = is_string($key) ? $key : $oldNodeName . '_' . $key;

或者如果你正在处理以s结尾的复数:

$key = is_string($key) ? $key : preg_replace('/s$/', '', $oldNodeName);

来自PHP 5.4

function array2xml($data, $root = null){
    $xml = new SimpleXMLElement($root ? '<' . $root . '/>' : '<root/>');
    array_walk_recursive($data, function($value, $key)use($xml){
        $xml->addChild($key, $value);
    });
    return $xml->asXML();
}