JAVASCRIPT

download file from any url

function download(url, filename) {
fetch(url).then(function(t) {
    return t.blob().then((b)=>{
        var a = document.createElement("a");
        a.href = URL.createObjectURL(b);
        a.setAttribute("download", filename);
        a.click();
    }
    );
});
}

download("https://get.geojs.io/v1/ip/geo.json","geoip.json")
download("data:text/html,HelloWorld!", "helloWorld.txt");

Download file from url

//
DownloadManager manager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
                Uri uri = Uri.parse("https://www.w3.org/WAI/ER/tests/xhtml/testfiles/resources/pdf/dummy.pdf");
                DownloadManager.Request request = new DownloadManager.Request(uri);
                request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE);
                long reference = manager.enqueue(request);