Android webview和downloadManager始终需要2个api调用吗？

Question

我正在具有网络视图的应用程序中实现下载功能。我正在尝试从mpdf输出中下载带有“ D”目标的$mpdf->Output($fileName,'D');

在PHP端，我注意到它总是被两次调用，大概是从浏览器API调用中，并且在downloadListener上也被downloadManager调用了enqueue。

总是这样吗？还是有更好的方法不两次调用api？

我已经实现了这样的downloadListener

webView.setDownloadListener(new DownloadListener() {
    @Override
    public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimeType, long contentLength) {

        if (url.startsWith("data:")) {
            // TODO: HANDLE DATA AND BLOB URLS
            return;
        }

        Uri sourceUrl = Uri.parse(url);
        String cookies = getCookie(sourceUrl.getHost());

        // CREATE REQUEST
        DownloadManager.Request request = new DownloadManager.Request(sourceUrl);

        // INJECT HEADERS
        request.addRequestHeader("Cookie", cookies);
        request.addRequestHeader("User-Agent", userAgent);

        // SET FILENBAME
        String filename = URLUtil.guessFileName(url, contentDisposition, mimeType);

        // SET REQUEST PARAMETERS
        request.setTitle(filename);
        request.allowScanningByMediaScanner();
        request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
        request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, filename);

        // DOWNLOAD
        dm.enqueue(request);

    }
});