why resubmit after refresh php page?

try it, go to: http://qass.im/message-envelope/

and upload any image

now try click F5, after refresh page "resubmit"

Why?

I don't want resubmit after refresh page

What is the solution?

See this is my form code:

<form id="uploadedfile" name="uploadedfile" enctype="multipart/form-data" action="upload.php" method="POST">
<input name="uploadedfile" type="file" />
<input type="submit" value="upload" />
</form>

See this is php code upload.php file:

<?php
$allowedExts = array("gif", "jpeg", "jpg", "png", "zip", "pdf", "docx", "rar", "txt", "doc");
$temp = explode(".", $_FILES["uploadedfile"]["name"]);
$extension = end($temp);
$newname = $extension.'_'.substr(str_shuffle(str_repeat("0123456789abcdefghijklmnopqrstuvwxyz", 7)), 4, 7);
$imglink = 'attachment/attachment_file_';
$uploaded = $imglink .$newname.'.'.$extension;
if ((($_FILES["uploadedfile"]["type"] == "image/jpeg")
|| ($_FILES["uploadedfile"]["type"] == "image/jpeg")
|| ($_FILES["uploadedfile"]["type"] == "image/jpg")
|| ($_FILES["uploadedfile"]["type"] == "image/pjpeg")
|| ($_FILES["uploadedfile"]["type"] == "image/x-png")
|| ($_FILES["uploadedfile"]["type"] == "image/gif")
|| ($_FILES["uploadedfile"]["type"] == "image/png")
|| ($_FILES["uploadedfile"]["type"] == "application/msword")
|| ($_FILES["uploadedfile"]["type"] == "text/plain")
|| ($_FILES["uploadedfile"]["type"] == "application/vnd.openxmlformats-officedocument.wordprocessingml.document")
|| ($_FILES["uploadedfile"]["type"] == "application/pdf")
|| ($_FILES["uploadedfile"]["type"] == "application/x-rar-compressed")
|| ($_FILES["uploadedfile"]["type"] == "application/x-zip-compressed")
|| ($_FILES["uploadedfile"]["type"] == "application/zip")
|| ($_FILES["uploadedfile"]["type"] == "multipart/x-zip")
|| ($_FILES["uploadedfile"]["type"] == "application/x-compressed")
|| ($_FILES["uploadedfile"]["type"] == "application/octet-stream"))
&& ($_FILES["uploadedfile"]["size"] < 5242880) // Max size is 5MB
&& in_array($extension, $allowedExts))
{   
move_uploaded_file($_FILES["uploadedfile"]["tmp_name"],
$uploaded );
echo '<a target="_blank" href="'.$uploaded.'">click</a>'; // If has been uploaded file
echo '<h3>'.$uploaded.'</h3>';
}
if($_FILES["uploadedfile"]["error"] > 0){
echo '<h3>Please choose file to upload it!</h3>'; // If you don't choose file
}
elseif(!in_array($extension, $allowedExts)){
echo '<h3>This extension is not allowed!</h3>'; // If you choose file not allowed
}
elseif($_FILES["uploadedfile"]["size"] > 5242880){
echo "Big size!"; // If you choose big file
}
?>

if you have solution, please edit my php code and paste your solution code!

Thanks.