有哪些php中xml转换json的方法

require_once 'json/JSON.php';
// Internal program-specific Debug option.
define ("DEBUG", false);
// Maximum Recursion Depth that we can allow.
define ("MAX_RECURSION_DEPTH_ALLOWED", 25);
// An empty string
define ("EMPTY_STR", "");
// SimpleXMLElement object property name for attributes
define ("SIMPLE_XML_ELEMENT_OBJECT_PROPERTY_FOR_ATTRIBUTES", "@attributes");
// SimpleXMLElement object name.
define ("SIMPLE_XML_ELEMENT_PHP_CLASS", "SimpleXMLElement");

public static function transformXmlStringToJson($xmlStringContents) {
 $simpleXmlElementObject = simplexml_load_string($xmlStringContents); 
<br>
    if ($simpleXmlElementObject == null) {
 return(EMPTY_STR);
 }
<br>
    $jsonOutput = EMPTY_STR; 
<br>
    // Let us convert the XML structure into PHP array structure.
 $array1 = xml2json::convertSimpleXmlElementObjectIntoArray($simpleXmlElementObject);
<br>
    if (($array1 != null) && (sizeof($array1) > 0)) { 
 // Create a new instance of Services_JSON
 $json = new Services_JSON();
 // Let us now convert it to JSON formatted data.
 $jsonOutput = $json->encode($array1);
 } // End of if (($array1 != null) && (sizeof($array1) > 0))
<br>
    return($jsonOutput); 
} // End of function transformXmlStringToJson

public static function convertSimpleXmlElementObjectIntoArray($simpleXmlElementObject,
&$recursionDepth=0) {
 // Keep an eye on how deeply we are involved in recursion.
<br>
    if ($recursionDepth > MAX_RECURSION_DEPTH_ALLOWED) {
 // Fatal error. Exit now.
 return(null);
 }
<br>
    if ($recursionDepth == 0) {
 if (get_class($simpleXmlElementObject) != SIMPLE_XML_ELEMENT_PHP_CLASS) {
 // If the external caller doesn't call this function initially
 // with a SimpleXMLElement object, return now.
 return(null);
 } else {
 // Store the original SimpleXmlElementObject sent by the caller.
 // We will need it at the very end when we return from here for good.
 $callerProvidedSimpleXmlElementObject = $simpleXmlElementObject;
 }
 } // End of if ($recursionDepth == 0) {
<br>
    if (get_class($simpleXmlElementObject) == SIMPLE_XML_ELEMENT_PHP_CLASS) {
        // Get a copy of the simpleXmlElementObject
        $copyOfsimpleXmlElementObject = $simpleXmlElementObject;
        // Get the object variables in the SimpleXmlElement object for us to iterate.
        $simpleXmlElementObject = get_object_vars($simpleXmlElementObject);
    }
<br>
    // It needs to be an array of object variables.
    if (is_array($simpleXmlElementObject)) {
        // Is the array size 0? Then, we reached the rare CDATA text if any.
        if (count($simpleXmlElementObject) <= 0) {
            // Let us return the lonely CDATA. It could even be
            // an empty element or just filled with whitespaces.
            return (trim(strval($copyOfsimpleXmlElementObject)));
        }
<br>
        // Let us walk through the child elements now.
        foreach($simpleXmlElementObject as $key=>$value) {
            // When this block of code is commented, XML attributes will be
            // added to the result array.
            // Uncomment the following block of code if XML attributes are
            // NOT required to be returned as part of the result array.
            /*
            if($key == SIMPLE_XML_ELEMENT_OBJECT_PROPERTY_FOR_ATTRIBUTES) {
                continue;
            }
            */
<br>
            // Let us recursively process the current element we just visited.
            // Increase the recursion depth by one.
            $recursionDepth++;
            $resultArray[$key] =
                xml2json::convertSimpleXmlElementObjectIntoArray($value, $recursionDepth);
<br>
            // Decrease the recursion depth by one.
            $recursionDepth--;
        } // End of foreach($simpleXmlElementObject as $key=>$value) {
<br>
        if ($recursionDepth == 0) {
            // That is it. We are heading to the exit now.
            // Set the XML root element name as the root [top-level] key of
            // the associative array that we are going to return to the caller of this
            // recursive function.
            $tempArray = $resultArray;
            $resultArray = array();
            $resultArray[$callerProvidedSimpleXmlElementObject->getName()] = $tempArray;
        }
<br>
        return ($resultArray);
    } else {
        // We are now looking at either the XML attribute text or
        // the text between the XML tags.
        return (trim(strval($simpleXmlElementObject)));
    } // End of else
} // End of function convertSimpleXmlElementObjectIntoArray.

<?php
    require_once("xml2json.php");
<br>
    // Filename from where XML contents are to be read.
    $testXmlFile = "";
<br>
    // Read the filename from the command line.
    if ($argc <= 1) {
        print("Please provide the XML filename as a command-line argument:\n");
        print("\tphp -f xml2json_test.php test1.xml\n");
        return;
    } else {
        $testXmlFile = $argv[1];
    }
<br>
    //Read the XML contents from the input file.
    file_exists($testXmlFile) or die('Could not find file ' . $testXmlFile);
    $xmlStringContents = file_get_contents($testXmlFile);
<br>
    $jsonContents = "";
    // Convert it to JSON now.
    // xml2json simply takes a String containing XML contents as input.
    $jsonContents = xml2json::transformXmlStringToJson($xmlStringContents);
<br>
    echo("JSON formatted output generated by xml2json:\n\n");
    echo($jsonContents);
?>

php -f xml2json_test.php test2.xml

<?xml version="1.0" encoding="UTF-8"?>
<books>
    <book id="1">
        <title>Code Generation in Action</title>
        <author><first>Jack</first><last>Herrington</last></author>
        <publisher>Manning</publisher>
    </book>
<br>
    <book id="2">
        <title>PHP Hacks</title>
        <author><first>Jack</first><last>Herrington</last></author>
        <publisher>O'Reilly</publisher>
    </book>
<br>
    <book id="3">
        <title>Podcasting Hacks</title>
        <author><first>Jack</first><last>Herrington</last></author>
        <publisher>O'Reilly</publisher>
    </book>
</books>

{
 "books" : {
 "book" : [ {
 "@attributes" : {
 "id" : "1"
 }, 
 "title" : "Code Generation in Action", 
 "author" : {
 "first" : "Jack", "last" : "Herrington"
 }, 
 "publisher" : "Manning"
 }, {
 "@attributes" : {
 "id" : "2"
 }, 
 "title" : "PHP Hacks", "author" : {
 "first" : "Jack", "last" : "Herrington"
 }, 
 "publisher" : "O'Reilly"
 }, {
 "@attributes" : {
 "id" : "3"
 }, 
 "title" : "Podcasting Hacks", "author" : {
 "first" : "Jack", "last" : "Herrington"
 }, 
 "publisher" : "O'Reilly"
 }
 ]}
}