如果文件已经下载，DownloadManager 不下载文件

Question

我正在使用DownloadManager 下载我的应用程序文件。 如果我再次将 url 放入 DownloadManager 中，它会下载文件并在末尾放置 -1 filename-1.file。有没有办法不让DownloadManager 再次下载它？还是我必须自己检查？

代码：

private void downloadImages(final List<SomeClass> data) {
    RuntimeExceptionDao<SomeClass, Integer> someDao = DatabaseAdapter.getInstance().getSomeDao();
    DownloadManager downloadmanager = (DownloadManager) mContext.getSystemService(Context.DOWNLOAD_SERVICE);
    for(SomeClass someClass : data){
        DownloadManager.Request request = getRequest(someClass);
        someClass.mDownloadId = downloadmanager.enqueue(request);
        someDao.createOrUpdate(someClass);
    }
}

private DownloadManager.Request getRequest(SomeClass someClass) {
    Uri uri = Uri.parse(someClass.mImage);
    DownloadManager.Request request = new DownloadManager.Request(uri);
    request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_HIDDEN);
    request.setVisibleInDownloadsUi(false);
    request.setDestinationInExternalFilesDir(mContext, Environment.DIRECTORY_DOWNLOADS, car.getFileName());
    return request;
}

Answer 1

这就是我的解决方法，您必须向下载管理器进行查询并验证是否已经存在具有相同标题的下载。如果没有任何巧合，那么我创建一个文件并使用存在函数来验证它是否已经在下载目录中。如果没有，我开始下载。

downloadManager = (DownloadManager) getActivity().getSystemService(Context.DOWNLOAD_SERVICE);

gridview.setOnItemClickListener(new OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View v, int position, long id) {

            //Crear objeto file con la ruta
            File ExistingFile =  new File(Environment.getExternalStoragePublicDirectory(
                    Environment.DIRECTORY_DOWNLOADS) + "/" + Archivos.get(position).getNombre());

            //Checar el downloadManager
            Cursor cursor = downloadManager.query( new Query() ); 
            boolean IsInDownloadManager;

            IsInDownloadManager = false;
            for (int i = 0; i < cursor.getCount() ; i++)
            {
                cursor.moveToPosition(i);
                Log.i("Click Grid", "Objetos en download manager [" + String.valueOf(i) + "] " + cursor.getString(cursor.getColumnIndex(DownloadManager.COLUMN_TITLE)));
                if (Archivos.get(position).getNombre().equals(cursor.getString(cursor.getColumnIndex(DownloadManager.COLUMN_TITLE)))){                                          
                    IsInDownloadManager = true;
                    Log.i("Click Grid", "Objeto está en download Manager " + Archivos.get(position).getNombre());
                    break;
                }
            }

            if (IsInDownloadManager){
                //cursor esta aputando a la fila donde se quedó en el ciclo for
                int Status = cursor.getInt(cursor.getColumnIndex(DownloadManager.COLUMN_STATUS));
                Log.i("Click Grid", cursor.getString(cursor.getColumnIndex(DownloadManager.COLUMN_STATUS)));

                if (Status == DownloadManager.STATUS_SUCCESSFUL){
                    Toast.makeText(getActivity() ,"Abriendo " +  Archivos.get(position).getNombre(), Toast.LENGTH_SHORT).show(); 
                    try { openFile(getActivity(),ExistingFile ); } catch (IOException e) {e.printStackTrace();}
                }else{
                     Toast.makeText(getActivity() ,Archivos.get(position).getNombre() + " ya se está descargando", Toast.LENGTH_SHORT).show();    
                }

            }else{

                if( ExistingFile.exists() ){
                    Toast.makeText(getActivity() ,"Abriendo " +  Archivos.get(position).getNombre(), Toast.LENGTH_SHORT).show();    
                    try { openFile(getActivity(),ExistingFile ); } catch (IOException e) {e.printStackTrace();}
                }else{
                    DescargarArchivo( Archivos.get(position) );
                }
            }

        }});