写入 SD 卡时 Android csv 文件不可见

Question

I have been having an issue that others on the site have already. I have tried those solutions and they did not work for me.

I'm currently developing an app that would create a csv file based on user input. The file needs to be retrievable by the user when the device is connected to a PC via USB. The saving code functions work correctly, however the file is not visible on the PC when the device is connected.

This is the full saving code snippet of the app:

    FileWriter fileWriter = null;
    File sdCard = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM);
    File dir = new File(sdCard.getAbsolutePath() + "/appFolder/");
    File dir2 = new File(sdCard.getAbsolutePath() + "/appFolder/appSubFolder/");
    dir.mkdirs();
    dir2.mkdirs();
    fileName = clientName + " " + agentName + ".csv";
    path = sdCard.getAbsolutePath() + "/appFolder/appSubFolder/";
    file = new File(dir2, fileName);

    dir.setReadable(true);
    dir.setWritable(true);
    dir.setExecutable(true);

    dir2.setReadable(true);
    dir2.setWritable(true);
    dir2.setExecutable(true);

    file.setReadable(true);
    file.setWritable(true);
    file.setExecutable(true);

    this.clientName = clientName;
    this.agentName = agentName;
    BufferedWriter bufferedWriter = null;
    try {
        if(!dir.exists()){
            dir.createNewFile();
            Toast.makeText(context,"dir created", Toast.LENGTH_SHORT).show();
        }
        if(!dir2.exists()){
            dir2.createNewFile();
            Toast.makeText(context,"dir2 created", Toast.LENGTH_SHORT).show();
        }
        if (!file.exists() )
        {
            file.createNewFile();
            Toast.makeText(context,"file created", Toast.LENGTH_SHORT).show();
        }
        /*
        fileWriter = new FileWriter(file, true);
        bufferedWriter = new BufferedWriter(fileWriter);
        bufferedWriter.write(fullOrder);

        fileWriter.flush();
        bufferedWriter.flush();
        bufferedWriter.close();
        fileWriter.close();
        */

        FileOutputStream fileOutputStream = new FileOutputStream(file);
        OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream);
        outputStreamWriter.append(fullOrder);
        outputStreamWriter.close();
        fileOutputStream.close();

        MediaScannerConnection.scanFile(context, new String[]{file.toString()}, null, null);
        context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.fromFile(dir)));
        context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.fromFile(dir2)));
        context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.fromFile(file)));
    } catch (IOException ioEx) {
        Toast.makeText(context, ioEx.toString(), Toast.LENGTH_SHORT).show();
        Log.d("mTag", "msg");
        Log.d("Exception ioEx 1", ioEx.toString());
    } catch (Exception ex) {
        Toast.makeText(context, ex.toString(), Toast.LENGTH_SHORT).show();
        Log.d("mTag", "msg");
        Log.d("Genereic ex saveToFile", ex.toString());
    }

The file is being written to external storage and while I can see that more space is taken up, the file itself is still not visible.

Any help with what might be the problem would be appreciate. Thank you!

Answer 1

The way you are sending broadcast to MediaScanner but may not work efficiently and is not recommended too.

The recommended way is to add the file paths of the files which have been created/updated, like this [in a String type ArrayList]

ArrayList<String> filesToBeScanned = new ArrayList<String>();
filesToBeScanned.add(item.getFilePath());

Now you need to run scanFile() static method of the MediaScannerConnection class and pass the String array containing the list of all the files which have been created/updated and needs to be media scanned.

You can also put a listener to respond when the scanning has been finished for individual files.

String[] toBeScannedStr = new String[toBeScanned.size()]; toBeScannedStr = fileToBeScanned.toArray(toBeScannedStr);

            MediaScannerConnection.scanFile(getActivity(), toBeScannedStr, null, new OnScanCompletedListener() {

                @Override
                public void onScanCompleted(String path, Uri uri) {
                    System.out.println("SCAN COMPLETED: " + path);

                }
            });

Hope this solves your prob.

Answer 2

For internal storage use:

getFilesDir() or getCacheDir()

See android documentation:
https://developer.android.com/training/data-storage