对 XML 文件中的条目进行计数

Question

有没有办法计算给定 xml 文件中有多少条目？

示例：http://world.needforspeed.com/SpeedAPI/ws/game/nfsw/driver/rackemup420/cars?output=xml

我的代码：

// The POST URL and parameters      
$request =  'http://world.needforspeed.com/SpeedAPI/ws/game/nfsw/driver/'.$u.'/cars?output=xml';      

// Get the curl session object      
$session = curl_init($request);      

// Set the POST options.  
curl_setopt($session, CURLOPT_HEADER, true);      
curl_setopt($session, CURLOPT_RETURNTRANSFER, true);      

// Do the POST and then close the session      
$response = curl_exec($session);      
curl_close($session);      

// Get HTTP Status code from the response      
$status_code = array();      
preg_match('/\d\d\d/', $response, $status_code);      

// Check for errors      
switch( $status_code[0] ) {      
    case 200:      
        // Success      
        break;      
    case 503:      
        die('Service unavailable. An internal problem prevented us from returning data to you.');      
        break;      
    case 403:      
        die('Forbidden. You do not have permission to access this resource, or are over your rate limit.');      
        break;      
    case 400:      
        // You may want to fall through here and read the specific XML error      
        die('Bad request. The parameters passed to the service did not match as expected. The exact error is returned in the XML response.');      
        break;      
    default:      
        die('Your call returned an unexpected HTTP status of:' . $status_code[0]);      
}      

// Get the XML from the response, bypassing the header      
if (!($xml = strstr($response, '<?xml'))) {      
    $xml = null;      
}      

// Output the XML      

$worldCar = simplexml_load_string($xml);     
foreach ($worldCar->worldCar as $cars)        
{    

    $playercarid = $cars['carId'];      
    $playercarmake = $cars['make'];      
    $playercarname = $cars['carName'];   

        $playercaraccel = $cars->physicsProfile['acceleration'];      
        $playercarhandle = $cars->physicsProfile['handling'];      
        $playercarrating = $cars->physicsProfile['rating'];  
        $playercarspeed = $cars->physicsProfile['topSpeed'];  
        $playercartier = $cars->physicsProfile['tier'];  
}  

Answer 1

获取计数

count( $worldCar->xpath('worldCar') );

循环（这是你的问题，你只能得到第一辆 worldCar）

foreach ($worldCar->xpath('worldCar') as $node)
{
  ...
}

或者

foreach ($worldCar->children() as $node)
{
  ..
}

Answer 2

我认为您需要先加载文件： 查看 PHP 手册以获取有关加载 XML 文件的条目Here

然后，一旦您将文档加载到内存中，我相信您会使用“XMLReader”对象来遍历节点并在执行过程中增加一个独立的计数器变量。

我相信this 文章讨论了 read-and-advance-to-next-node 操作，尽管阅读该文章底部的 cmets，如果您有一个非常大的 XML 文件，您可能会用完记忆。请注意不要尝试解析 1Tb 文件或其他内容... :)

祝你好运！

H

编辑：看起来你可以使用 XMLReader 对象来打开你想要阅读的文件，而且看起来为了这篇文章的目的，你会想要使用 XMLReader->next();

简单的代码示例可能如下所示：

$nodeCount = 1;
$xr = XMLReader::open("myxmlfile.xml"); //Called staticly, returns an XMLReader object or false!
if(xr != false) // Check to see if its a valid object
{
   while($xr->next() == true) //Iterate through all the nodes
   {
      $nodeCount++; //increment an accumulator
   }
}
echo "$nodeCount nodes were found!";