谷歌地理定位器:使用simplexml_load_file时，直接URL有效，状态代码620

我对此有点困惑。

我正在尝试查找lats&lngs的商店定位器，并一直在使用谷歌的Geolocator和他们的教程http://code.google.com/apis/maps/articles/phpsqlgeocode.html，但除了可怕的620查询过多错误之外，似乎无法返回任何其他内容。

对我来说，真正奇怪的是，如果我将$request_url复制到浏览器中，我会获得预期的所有XML，但使用PHP的simplexml_load_file（$request_url）总是返回错误代码620，无论延迟多长时间，无论我使用多少不同的API密钥。

有人知道这是怎么回事吗？我是不是犯了什么可怕的错误？

我的代码如下，请原谅广泛的评论和回应：

<?php   
$host = 'xxx';
$db = 'xxx';
$u = 'xxx';
$p = 'xxx';
define("MAPS_HOST", "maps.google.com");
define("KEY", "xxx");  
// Opens a connection to a MySQL server
$connection = mysql_connect($host, $u, $p);
if (!$connection) {
  die("Not connected : " . mysql_error());
}
// Set the active MySQL database
$db_selected = mysql_select_db($db, $connection);
if (!$db_selected) {
  die("Can''t use db : " . mysql_error());
}
// Select all the rows in the markers table
$query = "SELECT * FROM BH_locations";
$result = mysql_query($query);
if (!$result) {
  die("Invalid query: " . mysql_error());
}
// Initialize delay in geocode speed
$delay = 0; 
$base_url = "http://" . MAPS_HOST . "/maps/geo?output=xml" . "&key=" . KEY;
// Iterate through the rows, geocoding each address
while ($row = @mysql_fetch_assoc($result)) {   
    echo '<br /><br />row#' . $row['id'] . '<br />';
    $geocode_pending = true;
    while ($geocode_pending) {    
        echo 'started while loop at ' . date('G:i:s:u') . '<br />';
        $address = $row["address"] . ', ' . $row['city'] . ', ' . $row['state'] . ' ' . $row['zip'];  
        echo $address . '<br />';       
        $id = $row["id"];
        $request_url = $base_url . "&q=" . urlencode($address);      
        echo 'request url: ' . $request_url . '<br />';
        $xml = simplexml_load_file($request_url) or die("url not loading"); 
        echo '<pre>';
        var_dump($xml);
        echo '</pre>';
        $status = $xml->Response->Status->code;
        if (strcmp($status, "200") == 0) {
            // Successful geocode
            echo '<br /><strong>WOOHOO IT WORKED!!!</strong><br />';
            $geocode_pending = false;

            /*
            $coordinates = $xml->Response->Placemark->Point->coordinates;
            $coordinatesSplit = split(",", $coordinates);
            // Format: Longitude, Latitude, Altitude
            $lat = $coordinatesSplit[1];
            $lng = $coordinatesSplit[0];
            $query = sprintf("UPDATE BH_locations " .
                " SET latitude = '%s', longitude = '%s' " .
                " WHERE id = '%s' LIMIT 1;",
                mysql_real_escape_string($lat),
                mysql_real_escape_string($lng),
                mysql_real_escape_string($id));
            $update_result = mysql_query($query);
            if (!$update_result) {
                die("Invalid query: " . mysql_error());
            } 
            */

        } else if (strcmp($status, "620") == 0) {
            // sent geocodes too fast
            $delay += 100000;    
            echo 'error 620<br /><br />';
        } else {
            // failure to geocode
            $geocode_pending = false;
            echo "Address " . $address . " failed to geocoded. ";
            echo "Received status " . $status . "'n";
        }
        usleep($delay);      
    } 
}     
?>