使用php检查文件夹是否存在，如果没有在文件上传脚本上

I'm trying to make a PHP script for mp3 uploads, But I want to make a folder on upload if one does not exists, using the user's session $_SESSION[username] in folder mp3/, when i run at the command line i get no error's but when i try to up load a mp3 it fails everytime ,and dose not make the folder .

<?php 


session_start();

if (isset      ($_SESSION ['band_id'  ]))
{
    $band_id  = $_SESSION ['band_id'  ];
    $bandname = $_SESSION ['bandname' ];
    $username = $_SESSION ['username' ];
}

// set database connection

require("connect.php");



// lets get our posts //
$song     = $_FILES['song_name'];
// folder that will hold songs
$songpath = '/mp3/' . $_SESSION['username'];

// song-file pathname
$songpath .= $song['name'];

if (!file_exists($songpath)) {
    mkdir($songpath."/".$_SESSION['username'], "/" ,0777,true);
}

var_dump($songpath);

// move the file from the tmp folder to the song folder
if (move_uploaded_file ($song['tmp_name'], $songpath))
{
    print "<p>Upload succeeded thank you</p>
";
}
else
{
    print "<p>Upload failed, sorry</p>
";
}

print <<<END
<p>
To continue, <a href="index.php">click here.</a>
</p>
</body>
</html>
END;

?>

so I was able to play around with the code, got it to work with a little help from a friend Thank's Oldcoder. In a nutshell, I had to give the absolute path, check to see if the mp3 folder is there if not make one, then check if the user had a folder /mp3/user seems to work pretty well :)

<?php




session_start();

if (isset      ($_SESSION ['band_id'  ]))
{
    $band_id  = $_SESSION ['band_id'  ];
    $bandname = $_SESSION ['bandname' ];
    $username = $_SESSION ['username' ];
}

// set database connection

require("connect.php");



// lets get our posts //
$song     = $_FILES["song_file"]["name"];
// Main MP3-files directory
$mp3dir   = '/var/www/ympradio.com/public_html/mp3';

// Create it, if necessary
if (!file_exists ($mp3)) {
    mkdir ($mp3dir, 0777, true);
}

// Folder that will hold user's files
$songdir = $mp3dir . '/' . $_SESSION ['username'];

// Create it, if necessary
if (!file_exists ($songdir)) {
    mkdir ($songdir, 0777, true);
}

// Song-file pathname
$songpath = $songdir . '/' . $song;

var_dump($songpath);

$songtemp = $_FILES["song_file"]["tmp_name"];

// move the file from the tmp folder to the song folder
if (move_uploaded_file ($songtemp, $songpath))
{
    print "<p>Upload succeeded thank you</p>
";
}
else
{
    print "<p>Upload failed, sorry</p>
";
    print "<p>($mp3dir) ($songdir) ($songpath)</p>";
}

print <<<END
<p>
To continue, <a href="index.php">click here.</a>
</p>
</body>
</html>
END;

?> 

You're using the wrong path for the directory.

Use this:

// lets get our posts //
$song     = $_FILES['song_name'];
// folder that will hold songs
$songdir = '/mp3/' . $_SESSION['username'] . '/';

// song-file pathname
$songpath = $songdir . $song['name'];

if (!file_exists($songdir)) {
    mkdir($songdir, 0777, true);
}

Check phpinfo(); What is tmp directory? Also check max_file_size and check your user right for all route