为服务器上的文件生成下载链接

Question

So I built a code that generates a zip file on my server and then deletes it every time a user requests to download the file on the client. There is just one more step that I am missing and I can't seem to be able to find a proper solution. Is there any way I could generate a temporary random link that the server would return to the client that would be a download link for this zip file?

    public String getDownloadLink(String[] files) throws IOException {
        
        [...] // Some stuff goes here but it is irrelevant to the situation. (I generate a download folder!)

        ZipUtil.pack(new File("Download"), new File("selected-files.zip"));

        // Generating a download link
        String downloadLink = ""; // This is what I am trying to figure out!!!


        // Deleting both the folder and the zip
        FileUtils.deleteDirectory(new File("Download"));
        File myObj = new File("selected-files.zip");
        if(myObj.delete()){} else{}

        // Download link
        return downloadLink;
}

Answer 1

A rather simple solution to this problem would be a random file name; one that a malicious client cannot guess, so only the initial client can have it.

A UUID can be used for this purpose as:

    //...
    String zipFileName = UUID.randomUUID().toString() + ".zip";
    ZipUtil.pack(new File("Download"), new File(zipFileName));
    //...
    String downloadLink = "https://my.server/download?fileName=" + zipFileName;
    //...

Then, when the client actually downloads the file, the request handler will have the fileName query parameter and use it to serve the file (and then perhaps delete it).