java - 从下载链接发现文件名和扩展名

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我正在尝试使用 download_url 下载文件但实际上这不是下载链接

当我点击 download_url Actual file 时下载开始，其中实际包含文件名和扩展名

现在我想发现文件名和扩展名

我已经尝试过了

FilenameUtils.getExtension(download_url); FilenameUtils.getName(download_url)

还有这个

URLUtil.guessFileName(download_url, null, null);

但是我得到一个空字符串，如何查找文件名和扩展名？

Answer 1

检查下面下载 PDF 文件并直接在 PDF 查看器中打开的代码:

    downloadButton.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            String URL = "www.XXXXX.com";

            if (NetworkUtil.isConnectingToInternet(getActivity())) {
                downloadPDFAsyncTask pdfAsyncTask = new downloadPDFAsyncTask();
                pdfAsyncTask.execute();
            } else {
                NetworkUtil.showDialog(getActivity(),
                        R.string.internetTitle,
                        R.string.internetMessage);
            }
        }
    });

} catch (NullPointerException e) {
    e.printStackTrace();
}
}

 private class downloadPDFAsyncTask extends
    AsyncTask<String, String, String> {

@Override
protected void onPreExecute() {
    super.onPreExecute();
    try {

        NetworkUtil.showProgressDialog(getActivity());

    } catch (Exception e) {
        e.printStackTrace();
    }
   }

@Override
protected String doInBackground(String... aurl) {
    try {

        System.out.println("URL >>>>> " + URL);

        URL url = new URL(URL);
        HttpURLConnection urlConnection = (HttpURLConnection) url
                .openConnection();

        urlConnection.setRequestMethod("GET");
        urlConnection.setDoOutput(true);

        // connect
        urlConnection.connect();

        checkAndCreateDirectory("/fileDirectory");

        file = new File(rootDir, "fileDirectory");
        System.out.println("file >>>>> " + file);

        FileOutputStream fileOutput = new FileOutputStream(file);

        // Stream used for reading the data from the internet
        InputStream inputStream = urlConnection.getInputStream();

        // this is the total size of the file which we are downloading
        totalSize = urlConnection.getContentLength();

        System.out.println("totalSize >>>>> " + totalSize);

        // create a buffer...
        byte[] buffer = new byte[1024 * 1024];
        int bufferLength = 0;

        while ((bufferLength = inputStream.read(buffer)) > 0) {
            fileOutput.write(buffer, 0, bufferLength);
            downloadedSize += bufferLength;
        }

        // close the output stream when complete //
        fileOutput.close();



    } catch (final MalformedURLException e) {
        e.printStackTrace();
    } catch (final IOException e) {
        e.printStackTrace();
    } catch (final Exception e) {
        e.printStackTrace();
    }
    return null;
}

@Override
protected void onPostExecute(String unused) {
    super.onPostExecute(unused);

    try {
        NetworkUtil.hideProgressDialog(getActivity());

        PackageManager packageManager = getActivity()
                .getPackageManager();
        Intent testIntent = new Intent(Intent.ACTION_VIEW);
        testIntent.setType("application/pdf");
        List<?> list = packageManager.queryIntentActivities(testIntent,
                PackageManager.MATCH_DEFAULT_ONLY);

        if (list.size() > 0 && file.isFile()) {
            Intent intent = new Intent();
            intent.setAction(Intent.ACTION_VIEW);
            Uri uri = Uri.fromFile(file);
            intent.setDataAndType(uri, "application/pdf");
            startActivity(intent);
        } else {


                NetworkUtil
                        .showDialog2(getActivity(), "Error",
                                "PDF Reader application is not installed in your device");

        }

    } catch (NullPointerException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}
  }


// function to verify if directory exists
public void checkAndCreateDirectory(String dirName) {
    File new_dir = new File(rootDir + dirName);
    if (!new_dir.exists()) {
        new_dir.mkdirs();
    }
}