php中xml轉換json的方法：首先需要使用SimpleXMLElement將XML內容轉換成適當的PHP資料型別；然後將PHP資料提供給【Services_JSON】編碼器；最後產生最終的JSON格式的輸出即可。
php中xml轉換json的方法：
越來越多的應用程式需要將XML 轉換成JSON。已經出現了一些基於 Web 的服務來執行這類轉換。 IBM T.J. Watson Research Center 開發了一種專門的方法，使用 PHP 進行這種轉換。此方法以 XML 字串資料為輸入並將其轉換成 JSON 格式的資料輸出。這種 PHP 的解決方案有以下幾個方面的優點：
可以獨立模式運行，在命令列下執行。
可以包含到已有伺服器端程式碼工件。
很容易承載為 Web 上的 Web 服務。
XML 到JSON 的轉換需要用到兩種PHP 核心特性：
SimpleXMLElement
Services_JSON
只需要這兩種PHP 核心特性，就可以將任何XML 資料轉換成JSON。首先，需要使用 SimpleXMLElement 將 XML 內容轉換成適當的 PHP 資料類型。然後將 PHP 資料提供給 Services_JSON 編碼器，後者再產生最終的 JSON 格式的輸出。
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#理解PHP 程式碼
這個xml2json 實作包含三個部分：
xml2json.php —— 這個PHP 類別包含兩個靜態函數
xml2json.php 中的常數
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");xml2json.php 中的Services_JSON
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($jsonOutput);
} // End of function transformXmlStringToJsonxml2json.php 中的轉換邏輯
public static function convertSimpleXmlElementObjectIntoArray($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.xml2json 測試驅動程式的實作
（4）中的程式碼片段是一個用於執行 xml2json 轉換器邏輯的測試驅動程式。 （4）xml2json_test.php
<?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"
}
]}
}请注意，
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