我有这个php脚本，它从谷歌API加载谷歌天气。
<?php
//Weather Forecast icon and temperature from google weather API
$setYourLanguage = "en"; // Possibilities: "en" - english; "ru" - russian; "ka" - georgian;
//WEATHER, read google XML weather forecast
$URL = "http://www.google.com/ig/api?weather=".$myCity."&hl=".$setYourLanguage."";
$dataInISO = file_get_contents($URL);
$dataInUTF = mb_convert_encoding($dataInISO, "UTF-8", "ISO-8859-2"); //fix Google's API UTF-8 bug
$xml = simplexml_load_string($dataInUTF);
$current = $xml->xpath("/xml_api_reply/weather/current_conditions");
$iconData = str_replace("/ig/images/weather/", "weather/", $current[0]->icon['data']);
$iconData = str_replace(".gif", ".png", $iconData);
?>
但有时页面无法加载，我在apache2日志中出错：
[Thu Aug 23 12:04:16 2012] [error] [client ::1] PHP Warning: simplexml_load_string(): Entity: line 1: parser error : Start tag expected, '<' not found in /Library/WebServer/Documents/wordpress/wp-content/themes/directorypress/homepage-structure.php on line 23
[Thu Aug 23 12:04:16 2012] [error] [client ::1] PHP Warning: simplexml_load_string(): Unsupported API in /Library/WebServer/Documents/wordpress/wp-content/themes/directorypress/homepage-structure.php on line 23
[Thu Aug 23 12:04:16 2012] [error] [client ::1] PHP Warning: simplexml_load_string(): ^ in /Library/WebServer/Documents/wordpress/wp-content/themes/directorypress/homepage-structure.php on line 23
[Thu Aug 23 12:04:16 2012] [error] [client ::1] PHP Fatal error: Call to a member function xpath() on a non-object in /Library/WebServer/Documents/wordpress/wp-content/themes/directorypress/homepage-structure.php on line 25
[Thu Aug 23 12:05:57 2012] [error] [client ::1] What
你知道为什么会这样吗？我的理论是，它无法正确连接到URL，并以这种方式失败。。。但是为什么页面加载停止了？有什么方法可以避免这个错误吗？并允许页面完全加载？
如果SimpleXml未能加载XML，则变量$xml的值为false，而不是类型为SimpleXMLElement的实例。也就是说，错误消息所说的：
〔Thu Aug 23 12:04:16 2012〕〔error〕〔client：：1〕PHP致命错误：在第25行的/Library/WebServer/Documents/wordpress/wp-content/themes/directorypress/homepage-structure.PHP中的非对象上调用成员函数xpath（）
因此，在访问对象上的函数之前，您应该对此进行检查。
if ($xml) {
$current = $xml->xpath("/xml_api_reply/weather/current_conditions");
$iconData = str_replace("/ig/images/weather/", "weather/", $current[0]->icon['data']);
$iconData = str_replace(".gif", ".png", $iconData);
}
然后，即使从Web服务加载XML失败，您的页面也将完全加载。