上传PHP后如何更改文件名

Question

Currently, my code uploads an image file with the name of the user submitted image. Now obviously I would want to change this to avoid overwriting problems. Now, I've had a look at some other suggestions but I can't seem to get it to work with my code (I've only been learning PHP for a few months). So, could you guys help me? Here's the upload code

<?php
$target_dir = "avatars/";
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
$uploadOk = 1;
$imageFileType = pathinfo($target_file,PATHINFO_EXTENSION);
// Check if image file is a actual image or fake image
if(isset($_POST["submit"])) {
    $check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);
    if($check !== false) {
        //echo "File is an image - " . $check["mime"] . ".";
        $uploadOk = 1;
    } else {
        echo "File is not an image.";
        $uploadOk = 0;
    }
}
// Check if file already exists
if (file_exists($target_file)) {
    echo "Sorry, file already exists.";
    $uploadOk = 0;
}
// Check file size
if ($_FILES["fileToUpload"]["size"] > 500000) {
    echo "Sorry, your file is too large.";
    $uploadOk = 0;
}
// Allow certain file formats
if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"
&& $imageFileType != "gif" ) {
    echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";
    $uploadOk = 0;
}
// Check if $uploadOk is set to 0 by an error
if ($uploadOk == 0) {
    echo "Sorry, your file was not uploaded.";
// if everything is ok, try to upload file
} else {
    if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
        //echo "The file ". basename( $_FILES["fileToUpload"]["name"]). " has been uploaded.";
    } else {
        echo "Sorry, there was an error uploading your file.";
    }
}
?>

My guess is that I would need to alter the move_uploaded_file code? Thanks for any help!

Answer 1

Change this:

$target_dir = "avatars/";
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);

To this:

$rand = rand(10000000, 999999999);
$time = time();
$file_name = $rand.$time.$_FILES["fileToUpload"]["name"];
$target_dir = "avatars/";
$target_file = $target_dir . $file_name;