php中SimpleXML生成与解析xml文件

class SimpleXMLExtended extends SimpleXMLElement {
  public function addCData($cdata_text) {
    $node = dom_import_simplexml($this);
    $no   = $node->ownerDocument;
    $node->appendChild($no->createCDATASection($cdata_text));
    }
  }
function array2xml($array, $xml = false){
    if($xml === false){
        $xml = new SimpleXMLExtended('');
    }
    foreach($array as $key => $value){
        if(is_array($value)){
            array2xml($value, $xml->addChild($key));
        }else{
            //如果包含汉字，转编码
            if (preg_match("/([x81-xfe][x40-xfe])/", $value, $match)) {
                $value = iconv('gbk', 'utf-8', $value);
            }
            $xml->$key = NULL; // VERY IMPORTANT! We need a node where to append
            $xml->$key->addCData($value);
            //$xml->$key->addAttribute('lang', 'en');
           // $xml->addChild($key, $value);
        }
    }
    return $xml->asXML();
}

$content = <<

 
  HTTP
  80
  /index.html
  5000
  3000
  2
  3
 
 
  
  
 

XML;

$test = new SimpleXMLElement($content);

//获得ping_protocol的值
$ping_protocol = $test->global_setting->ping_protocol;
echo "ping_protocol : $ping_protocol n";

//打印出所有instance的IP
foreach ( $test->instances->instance as $instance) {
 echo "IP: {$instance['ip']} n" ;
}