How to convert php xml to json format

function xmlToArray($xml, $options = array()) {
    $defaults = array(
        'namespaceSeparator' => ':',//you may want this to be something other than a colon
        'attributePrefix' => '@',   //to distinguish between attributes and nodes with the same name
        'alwaysArray' => array(),   //array of xml tag names which should always become arrays
        'autoArray' => true,        //only create arrays for tags which appear more than once
        'textContent' => '$',       //key used for the text content of elements
        'autoText' => true,         //skip textContent key if node has no attributes or child nodes
        'keySearch' => false,       //optional search and replace on tag and attribute names
        'keyReplace' => false       //replace values for above search values (as passed to str_replace())
    );
    $options = array_merge($defaults, $options);
    $namespaces = $xml->getDocNamespaces();
    $namespaces[''] = null; //add base (empty) namespace
 
    //get attributes from all namespaces
    $attributesArray = array();
    foreach ($namespaces as $prefix => $namespace) {
        foreach ($xml->attributes($namespace) as $attributeName => $attribute) {
            //replace characters in attribute name
            if ($options['keySearch']) $attributeName =
                    str_replace($options['keySearch'], $options['keyReplace'], $attributeName);
            $attributeKey = $options['attributePrefix']
                    . ($prefix ? $prefix . $options['namespaceSeparator'] : '')
                    . $attributeName;
            $attributesArray[$attributeKey] = (string)$attribute;
        }
    }
 
    //get child nodes from all namespaces
    $tagsArray = array();
    foreach ($namespaces as $prefix => $namespace) {
        foreach ($xml->children($namespace) as $childXml) {
            //recurse into child nodes
            $childArray = xmlToArray($childXml, $options);
            list($childTagName, $childProperties) = each($childArray);
 
            //replace characters in tag name
            if ($options['keySearch']) $childTagName =
                    str_replace($options['keySearch'], $options['keyReplace'], $childTagName);
            //add namespace prefix, if any
            if ($prefix) $childTagName = $prefix . $options['namespaceSeparator'] . $childTagName;
 
            if (!isset($tagsArray[$childTagName])) {
                //only entry with this key
                //test if tags of this type should always be arrays, no matter the element count
                $tagsArray[$childTagName] =
                        in_array($childTagName, $options['alwaysArray']) || !$options['autoArray']
                        ? array($childProperties) : $childProperties;
            } elseif (
                is_array($tagsArray[$childTagName]) && array_keys($tagsArray[$childTagName])
                === range(0, count($tagsArray[$childTagName]) - 1)
            ) {
                //key already exists and is integer indexed array
                $tagsArray[$childTagName][] = $childProperties;
            } else {
                //key exists so convert to integer indexed array with previous value in position 0
                $tagsArray[$childTagName] = array($tagsArray[$childTagName], $childProperties);
            }
        }
    }
 
    //get text content of node
    $textContentArray = array();
    $plainText = trim((string)$xml);
    if ($plainText !== '') $textContentArray[$options['textContent']] = $plainText;
 
    //stick it all together
    $propertiesArray = !$options['autoText'] || $attributesArray || $tagsArray || ($plainText === '')
            ? array_merge($attributesArray, $tagsArray, $textContentArray) : $plainText;
 
    //return node as array
    return array(
        $xml->getName() => $propertiesArray
    );
}

$xmlNode = simplexml_load_file('example.xml');
$arrayData = xmlToArray($xmlNode);
echo json_encode($arrayData);
JSON 转 XML
以下代码将 JSON 数据格式作为 XML 输出：
<?php
$json = stream_get_contents(STDIN);
$data = @json_decode($json, false);
if (!is_array($data) && !is_object($data)) {
    echo &#39;ERROR: Invalid JSON given&#39; . PHP_EOL;
    exit(1);
}
class Exporter
{
    private $root = &#39;document&#39;;
    private $indentation = &#39;    &#39;;
    // TODO: private $this->addtypes = false; // type="string|int|float|array|null|bool"
    public function export($data)
    {
        $data = array($this->root => $data);
        echo &#39;<?xml version="1.0" encoding="UTF-8">&#39;;
        $this->recurse($data, 0);
        echo PHP_EOL;
    }
    private function recurse($data, $level)
    {
        $indent = str_repeat($this->indentation, $level);
        foreach ($data as $key => $value) {
            echo PHP_EOL . $indent . &#39;<&#39; . $key;
            if ($value === null) {
                echo &#39; />&#39;;
            } else {
                echo &#39;>&#39;;
                if (is_array($value)) {
                    if ($value) {
                        $temporary = $this->getArrayName($key);
                        foreach ($value as $entry) {
                            $this->recurse(array($temporary => $entry), $level + 1);
                        }
                        echo PHP_EOL . $indent;
                    }
                } else if (is_object($value)) {
                    if ($value) {
                        $this->recurse($value, $level + 1);
                        echo PHP_EOL . $indent;
                    }
                } else {
                    if (is_bool($value)) {
                        $value = $value ? &#39;true&#39; : &#39;false&#39;;
                    }
                    echo $this->escape($value);
                }
                echo &#39;</&#39; . $key . &#39;>&#39;;
            }
        }
    }
    private function escape($value)
    {
        // TODO:
        return $value;
    }
    private function getArrayName($parentName)
    {
        // TODO: special namding for tag names within arrays
        return $parentName;
    }
}
$exporter = new Exporter();
$exporter->export($data);