How do I make a script to grab certain piece of data from a JSON API?

I'm trying to build a little script that would let me do this:

http://example.com/a开发者_Python百科ppicons.php?id=284417350

and then display this in plain text

http://a3.mzstatic.com/us/r1000/005/Purple/2c/a0/b7/mzl.msucaqmg.png

This is the API query to get that information (artworkUrl512):

http://ax.itunes.apple.com/WebObjects/MZStoreServices.woa/wa/wsLookup?id=284417350

Any help and example code would be much appreciated!

I am not sure why you have jQuery in your tags, unless you want to make the request dynamically without a page refresh. However you can do this simply in PHP using the following example:

$request            = array (
    "app_id"        => @$_GET["id"]
);
// parse the requests.
if (empty($request["app_id"])) {
    // redirects back / displays error
}
else {
    $app_uri    = "http://ax.itunes.apple.com/WebObjects/MZStoreServices.woa/wa/wsLookup?id=" . $request["app_id"];
    $data       = file_get_contents ($app_uri);
    $json       = json_decode (trim($data));
    print($json->results[0]->artworkUrl100);
}

$request = file_get_contents($itms_url);
$json = json_decode(trim($request));
echo $json[0]->artworkUrl512;

should work in PHP. Unless of course there is more than one hit to the search. A solution using jQuery is probably not very much more difficult.