Why doesn't file_get_contents work?

问题

Why does file_get_contents not work for me? In the test file code below, it seems that everyone's examples that I've searched for all have this function listed, but it never gets executed. Is this a problem with the web hosting service? Can someone test this code on their server just to see if the geocoding array output actually gets printed out as a string? Of course, I am trying to assign the output to a variable, but there is no output here in this test file....

<html>
<head>        
<title>Test File</title>
<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"> 
</script>
</head>
<body>
<?    
$adr = 'Sydney+NSW';
echo $adr;
$url = "http://maps.googleapis.com/maps/api/geocode/json?address=$adr&sensor=false";
echo '<p>'.$url.'</p>';
echo file_get_contents($url);
print '<p>'.file_get_contents($url).'</p>';
$jsonData   = file_get_contents($url);
echo $jsonData;
?>
</body>
</html>

回答1:

Check file_get_contents PHP Manual return value. If the value is FALSE then it could not read the file. If the value is NULL then the function itself is disabled.

To learn more what might gone wrong with the file_get_contents operation you must enable error reporting and the display of errors to actually read them.

# Enable Error Reporting and Display:
error_reporting(~0);
ini_set('display_errors', 1);

You can get more details about the why the call is failing by checking the INI values on your server. One value the directly effects the file_get_contents function is allow_url_fopen. You can do this by running the following code. You should note, that if it reports that fopen is not allowed, then you'll have to ask your provider to change this setting on your server in order for any code that require this function to work with URLs.

<html>
    <head>        
        <title>Test File</title>
        <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false">
        </script>
    </head>
    <body>
<?php

# Enable Error Reporting and Display:
error_reporting(~0);
ini_set('display_errors', 1);

$adr = 'Sydney+NSW';
echo $adr;
$url = "http://maps.googleapis.com/maps/api/geocode/json?address=$adr&sensor=false";
echo '<p>'.$url.'</p>';

$jsonData = file_get_contents($url);

print '<p>', var_dump($jsonData), '</p>';

# Output information about allow_url_fopen:
if (ini_get('allow_url_fopen') == 1) {
    echo '<p style="color: #0A0;">fopen is allowed on this host.</p>';
} else {
    echo '<p style="color: #A00;">fopen is not allowed on this host.</p>';
}


# Decide what to do based on return value:
if ($jsonData === FALSE) {
    echo "Failed to open the URL ", htmlspecialchars($url);
} elseif ($jsonData === NULL) {
    echo "Function is disabled.";
} else {
   echo $jsonData;
}

?>
    </body>
</html>

If all of this fails, it might be due to the use of short open tags, <?. The example code in this answer has been therefore changed to make use of <?php to work correctly as this is guaranteed to work on in all version of PHP, no matter what configuration options are set. To do so for your own script, just replace <? or <?php.

回答2:

If PHP's allow_url_fopen ini directive is set to true, and if curl doesn't work either (see this answer for an example of how to use it instead of file_get_contents), then the problem could be that your server has a firewall preventing scripts from getting the contents of arbitrary urls (which could potentially allow malicious code to fetch things).

I had this problem, and found that the solution for me was to edit the firewall settings to explicitly allow requests to the domain (or IP address) in question.

回答3:

If it is a local file, you have to wrap it in htmlspecialchars like so:

    $myfile = htmlspecialchars(file_get_contents($file_name));

Then it works

回答4:

Wrap your $adr in urlencode(). I was having this problem and this solved it for me.

回答5:

//JUST ADD urlencode();
$url = urlencode("http://maps.googleapis.com/maps/api/geocode/json?address=$adr&sensor=false");
<html>
<head>        
<title>Test File</title>
<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"> 
</script>
</head>
<body>
<?php    
$adr = 'Sydney+NSW';
echo $adr;
$url = "http://maps.googleapis.com/maps/api/geocode/json?address=$adr&sensor=false";
echo '<p>'.$url.'</p>';
echo file_get_contents($url);
print '<p>'.file_get_contents($url).'</p>';
$jsonData   = file_get_contents($url);
echo $jsonData;
?>
</body>
</html>

来源：https://stackoverflow.com/questions/6724467/why-doesnt-file-get-contents-work

标签

php

geocoding

file-get-contents