使用AsyncTask通过webview内部选项卡下载文件

public class DownloadFileTask extends AsyncTask<String, Integer, Boolean> {
    private Context mContext;
    
    public DownloadFileTask(Context context) {
        mContext = context;
    }
    
    @Override
    protected void onPreExecute() {
        // 初始化操作，例如显示进度条
    }
    
    @Override
    protected Boolean doInBackground(String... urls) {
        try {
            URL url = new URL(urls[0]);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.connect();
            
            int fileLength = connection.getContentLength();
            InputStream input = new BufferedInputStream(url.openStream());
            OutputStream output = new FileOutputStream(Environment.getExternalStorageDirectory() + "/downloaded_file.ext");
            
            byte[] data = new byte[1024];
            long total = 0;
            int count;
            while ((count = input.read(data)) != -1) {
                total += count;
                publishProgress((int) (total * 100 / fileLength));
                output.write(data, 0, count);
            }
            
            output.flush();
            output.close();
            input.close();
            return true;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }
    
    @Override
    protected void onProgressUpdate(Integer... progress) {
        // 更新进度条的进度
    }
    
    @Override
    protected void onPostExecute(Boolean result) {
        if (result) {
            Toast.makeText(mContext, "文件下载完成", Toast.LENGTH_SHORT).show();
        } else {
            Toast.makeText(mContext, "文件下载失败", Toast.LENGTH_SHORT).show();
        }
    }
}

DownloadFileTask downloadTask = new DownloadFileTask(MainActivity.this);
downloadTask.execute("http://example.com/file.ext");