保存前上传文件并重命名

Question

我从w3school获取此代码以将文件上传到服务器，如何将文件名更改为随机数，以免出现重复问题。有人可以协助向我展示上传文件的正确和最安全的方式。

// Change folder permission so that files can be uploaded
    chmod('_data/cvs/', 0777);

    // Upload File to Server
    $target_dir = "_data/cvs/";
    $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 != "doc" && $imageFileType != "docs" && $imageFileType != "pdf"
        && $imageFileType != "gif" ) {
            echo "Sorry, only Doc, Docs and PDF 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.";
            }
        }

    // Change folder permission so that nothing can be uploaded
    chmod('_data/cvs/', 0644);

提前致谢！

Answer 1

我通常使用的是time()函数。

我会改变这部分代码：

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