Android，下载和使用.db文件

Question

（对于我可怜的英语，我深感抱歉）

对于学校项目，我必须实现一个Android应用程序。它使用实习SQLite数据库，它是来自网站MySQL数据库的副本。 （android应用程序是电气工程数据库的搜索引擎） 由于它必须独立于网站（离线），我必须创建一个更新选项。

为此，我制作了一个特殊的DownloadHelper类：

@SuppressLint("SdCardPath")
public final class DownloadHelper extends AsyncTask<Void,Void,Void>
{
    Context context;
    File cheminBdd = new File("/data/data/com.example.btc_pe/databases/basesqlite.db");

    public DownloadHelper(Context ctxt)
      { this.context = ctxt; }

    @Override
    protected Void doInBackground(Void... params)
    {
        // TODO Auto-generated method stub
        try 
        {
            downloadDatabase(cheminBdd);
            //copyServerDatabase(this.context);
        } 
        catch (Exception ex) 
        {
            Log.e("BTC","Failed to download database !",ex);
        }

        return null;
    }


    private static void downloadDatabase(File destFile) throws IOException
    {        
        URLConnection ucon;
        InputStream is = null;
        OutputStream os = null;
        try 
        {
             Log.d("BTC","start DL");
             URL url = new URL("adresse" + "basesqlite.db");
             ucon = url.openConnection();
             Log.d("BTC","Connection open");
             is = ucon.getInputStream();
             Log.d("BTC","Stream In got");
             os = new FileOutputStream(destFile);
             Log.d("BTC","Debut copy()");
             copy(is,os);
             Log.d("BTC","end DL");
        } 
        finally 
        {
             if (os != null) try { os.close(); } catch (Exception ex) { Log.e("BTC","Failed to gracefully close output stream",ex); }
             if (is != null) try { is.close(); } catch (Exception ex) { Log.e("BTC","Failed to gracefully close input stream",ex); }
        } 
    }

    public static int copy(InputStream input, OutputStream output) throws IOException
    {
         byte[] buffer = new byte[8192];
         int count = 0;
         int n = 0;
         while (-1 != (n = input.read(buffer))) 
         {
             output.write(buffer, 0, n);
             count += n;
         }
         output.flush();
         return count;
     }


    @SuppressLint("SdCardPath")
    private void copyServerDatabase(Context context) 
    {
            BtcDb db = new BtcDb(context,"clean.db",null,0);
            // by calling this line an empty database will be created into the default system path
            // of this app - we will then overwrite this with the database from the server
            db.getReadableDatabase();
            db.close();


            OutputStream os = null;
            InputStream is = null;
            try {
                  // Log.d("BTC", "Copying DB from server version into app");
                    is = context.openFileInput("basesqlite.db");
                    os = new FileOutputStream("/data/data/com.example.btc_pe/databases/"); 

                    copyFile(os, is);
            } 
            catch (Exception e) 
            {
                    Log.e("BTC", "Server Database was not found - did it download correctly?", e);                          
            } 
            finally 
            {
                    try 
                    {
                            //Close the streams
                            if(os != null)
                            {
                                    os.close();
                            }
                            if(is != null)
                            {
                                    is.close();
                            }
                    } 
                    catch (IOException e) 
                    {
                            Log.e("BTC", "failed to close databases");
                    }
            }
            Log.d("BTC", "Done Copying DB from server");
      }




     private static void copyFile(OutputStream os, InputStream is) throws IOException 
     {
            byte[] buffer = new byte[1024];
            int length;
            while((length = is.read(buffer))>0)
            {
                    os.write(buffer, 0, length);
            }
            os.flush();
    }
}

我通过操作栏按钮调用更新，使用instanciated对象中的DownloadHelper.execute（）方法。 然后我在传递“is = ucon.getInputStream（）;”后得到一个异常，我得到这个LogCat： http://www.dump-it.fr/btcpng/7865ef3fef44de25fd62f01dad23d02d.png.html

当然，我在服务器，我的网址，我的Android设备上检查了这个文件。没事做。

如果有人能帮助我，我迷路了：/