我有以下代码来读取一个XML文件，该文件在URL可用时运行良好：
$url = 'http://www1.blahblah.com'."param1"."param2";
$xml = file_get_contents($url);
$obj = SimpleXML_Load_String($xml);
如果第一个URL由于任何原因不可用，我如何更改上面的代码以循环使用多个不同的URL？我有一个4个URL的列表，所有URL都包含同一个文件，但我不确定如何处理。
将您的代码替换为例如这个
//instead of simple variable use an array with links
$urls = [ 'http://www1.blahblah.com'."param1"."param2",
'http://www1.anotherblahblah.com'."param1"."param2",
'http://www1.andanotherblahblah.com'."param1"."param2",
'http://www1.andthelastblahblah.com'."param1"."param2"];
//for all your links try to get a content
foreach ($urls as $url) {
$xml = file_get_contents($url);
//do your things if content was read without failure and break the loop
if ($xml !== false) {
$obj = SimpleXML_Load_String($xml);
break;
}
}