Implementing a File Picker in Android and copying

问题:

I'm trying to implement a File Picker in my Android project. What I've been able to do so far is :

Intent chooseFile;
Intent intent;
chooseFile = new Intent(Intent.ACTION_GET_CONTENT);
chooseFile.setType("*/*");
intent = Intent.createChooser(chooseFile, "Choose a file");
startActivityForResult(intent, PICKFILE_RESULT_CODE);

And then in my onActivityResult()

switch(requestCode){
 case PICKFILE_RESULT_CODE:
   if(resultCode==-1){
      Uri uri = data.getData();
      String filePath = uri.getPath();
      Toast.makeText(getActivity(), filePath,
                        Toast.LENGTH_LONG).show();
    }
 break;
}

This is opening a file picker, but its not what I want. For example, I want to select a file (.txt), and then get that File and then use it. With this code I thought I would get the full path but it doesn't happen; for example I get: /document/5318/. But with this path I can't get the file. I've created a method called PathToFile() that returns a File :

 private File PathToFile(String path) {
    File tempFileToUpload;
    tempFileToUpload = new File(path);
    return tempFileToUpload;
}

What I'm trying to do is let the user choose a File from anywhere means DropBox, Drive, SDCard, Mega, etc... And I don't find the way to do it correctly, I tried to get the Path then get a File by this Path... but it doesn't work, so I think it's better to get the File itself, and then with this File programmatically I Copy this or Delete.

EDIT (Current code)

My Intent

 Intent chooseFile = new Intent(Intent.ACTION_GET_CONTENT);
 chooseFile.addCategory(Intent.CATEGORY_OPENABLE);
 chooseFile.setType("text/plain");
 startActivityForResult(
      Intent.createChooser(chooseFile, "Choose a file"),
      PICKFILE_RESULT_CODE
 );

There I've got a question because I don't know what is supported as text/plain, but I'm gonna investigate about it, but it doesn't matter at the moment.

On my onActivityResult() I've used the same as @Lukas Knuth answer, but I don't know if with it I can Copy this File to another part from my SDcard I'm waitting for his answer.

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == PICKFILE_RESULT_CODE && resultCode == Activity.RESULT_OK){
        Uri content_describer = data.getData();
        //get the path 
        Log.d("Path???", content_describer.getPath());
        BufferedReader reader = null;
        try {
            // open the user-picked file for reading:
            InputStream in = getActivity().getContentResolver().openInputStream(content_describer);
            // now read the content:
            reader = new BufferedReader(new InputStreamReader(in));
            String line;
            StringBuilder builder = new StringBuilder();

            while ((line = reader.readLine()) != null){
                builder.append(line);
            }
            // Do something with the content in
            text.setText(builder.toString());



        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

getPath() from @Y.S.

I'm doing this :

    String[] projection = { MediaStore.Files.FileColumns.DATA };
            Cursor cursor = getActivity().getContentResolver().query(content_describer, projection, null, null, null);
int column_index = cursor.getColumnIndexOrThrow(projection[0]);
cursor.moveToFirst();
cursor.close();
Log.d( "PATH-->",cursor.getString(column_index));

Is getting a NullPointerException :

java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=131073, result=-1, data=Intent { dat=file:///path typ=text/plain flg=0x3 }} to activity {info.androidhive.tabsswipe/info.androidhive.tabsswipe.MainActivity2}: java.lang.NullPointerException

EDIT with code working thanks to @Y.S., @Lukas Knuth, and @CommonsWare.

This is the Intent where I only accept files text/plain.

Intent chooseFile = new Intent(Intent.ACTION_GET_CONTENT);
chooseFile.addCategory(Intent.CATEGORY_OPENABLE);
chooseFile.setType("text/plain");
startActivityForResult(
    Intent.createChooser(chooseFile, "Choose a file"),
    PICKFILE_RESULT_CODE
);

On my onActivityResult() I create an URI where I get the data of the Intent, I create a File where I save the absolute path doing content_describer.getPath();, and then I keep the name of the path to use it in a TextView with content_describer.getLastPathSegment(); (that was awesome @Y.S. didn't know about that function), and I create a second File which I called destination and I send the AbsolutePath to can create this File.

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == PICKFILE_RESULT_CODE && resultCode == Activity.RESULT_OK){
        Uri content_describer = data.getData();
        String src = content_describer.getPath();
        source = new File(src);
        Log.d("src is ", source.toString());
        String filename = content_describer.getLastPathSegment();
        text.setText(filename);
        Log.d("FileName is ",filename);
        destination = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/Test/TestTest/" + filename);
        Log.d("Destination is ", destination.toString());
        SetToFolder.setEnabled(true);
    }
}

Also I've created a function that you have to send the source file, and destination file that we have created previously to copy this to the new folder.

private void copy(File source, File destination) throws IOException {

    FileChannel in = new FileInputStream(source).getChannel();
    FileChannel out = new FileOutputStream(destination).getChannel();

    try {
        in.transferTo(0, in.size(), out);
    } catch(Exception e){
        Log.d("Exception", e.toString());
    } finally {
        if (in != null)
            in.close();
        if (out != null)
            out.close();
    }
}

Also I've created a function that says to me if this folder exist or not (I have to send the destination file, if it doesn't exist I create this folder and if it does not I do not do nothing.

private void DirectoryExist (File destination) {

    if(!destination.isDirectory()) {
        if(destination.mkdirs()){
            Log.d("Carpeta creada","....");
        }else{
            Log.d("Carpeta no creada","....");
        }
    }

Thanks again for your help, hope you enjoy this code made with everyone of you guys :)

回答1:

STEP 1 - Use an Implicit Intent:

To choose a file from the device, you should use an implicit Intent

Intent chooseFile = new Intent(Intent.ACTION_GET_CONTENT);
chooseFile.setType("*/*");
chooseFile = Intent.createChooser(chooseFile, "Choose a file");
startActivityForResult(chooseFile, PICKFILE_RESULT_CODE);

STEP 2 - Get the absolute file path:

To get the file path from a Uri, first, try using

Uri uri = data.getData();
String src = uri.getPath();

where data is the Intent returned in onActivityResult().

If that doesn't work, use the following method:

public String getPath(Uri uri) {

    String path = null;
    String[] projection = { MediaStore.Files.FileColumns.DATA };
    Cursor cursor = getContentResolver().query(uri, projection, null, null, null);

    if(cursor == null){
        path = uri.getPath()
    }
    else{
        cursor.moveToFirst();
        int column_index = cursor.getColumnIndexOrThrow(projection[0]);
        path = cursor.getString(column_index);
        cursor.close();
    }

    return ((path == null || path.isEmpty()) ? (uri.getPath()) : path);
}

At least one of these two methods should get you the correct, full path.

STEP 3 - Copy the file:

What you want, I believe, is to copy a file from one location to another.

To do this, it is necessary to have the absolute file path of both the source and destination locations.

First, get the absolute file path using either my getPath() method or uri.getPath():

String src = getPath(uri);    /* Method defined above. */

or

Uri uri = data.getData();
String src = uri.getPath();

Then, create two File objects as follows:

File source = new File(src);
String filename = uri.getLastPathSegment();
File destination = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/CustomFolder/" + filename);

where CustomFolder is the directory on your external drive where you want to copy the file.

Then use the following method to copy a file from one place to another:

private void copy(File source, File destination) {

   FileChannel in = new FileInputStream(source).getChannel();
   FileChannel out = new FileOutputStream(destination).getChannel();

   try {
      in.transferTo(0, in.size(), out);
   } catch(Exception){
      // post to log
   } finally {
      if (in != null)
         in.close();
      if (out != null)
         out.close();
   }
}

Try this. This should work.

Note: Vis-a-vis Lukas' answer - what he has done is use a method called openInputStream() that returns the content of a Uri, whether that Uri represents a file or a URL.

Another promising approach - the FileProvider:

There is one more way through which it is possible to get a file from another app. If an app shares its files through the FileProvider, then it is possible to get hold of a FileDescriptor object which holds specific information about this file.

To do this, use the following Intent:

Intent mRequestFileIntent = new Intent(Intent.ACTION_GET_CONTENT);
mRequestFileIntent.setType("*/*");
startActivityForResult(mRequestFileIntent, 0);

and in your onActivityResult():

@Override
public void onActivityResult(int requestCode, int resultCode,
        Intent returnIntent) {
    // If the selection didn't work
    if (resultCode != RESULT_OK) {
        // Exit without doing anything else
        return;
    } else {
        // Get the file's content URI from the incoming Intent
        Uri returnUri = returnIntent.getData();
        /*
         * Try to open the file for "read" access using the
         * returned URI. If the file isn't found, write to the
         * error log and return.
         */
        try {
            /*
             * Get the content resolver instance for this context, and use it
             * to get a ParcelFileDescriptor for the file.
             */
            mInputPFD = getContentResolver().openFileDescriptor(returnUri, "r");
        } catch (FileNotFoundException e) {
            e.printStackTrace();
            Log.e("MainActivity", "File not found.");
            return;
        }
        // Get a regular file descriptor for the file
        FileDescriptor fd = mInputPFD.getFileDescriptor();
        ...
    }
}

where mInputPFD is a ParcelFileDescriptor.

References:

1. Common Intents - File Storage.

2. FileChannel.

3. FileProvider.

4. Requesting a Shared File.

回答2:

As @CommonsWare already noted, Android returns you a Uri, which is a more abstract concept than a file-path.

It can describe a simple file-path too, but it can also describe a resource that is accessed through an application (like content://media/external/audio/media/710).

If you want your user to pick any file from the phone to read it from your application, you can do so by asking for the file (as you did correctly) and then use the ContentResolver to get an InputStream for the Uri that is returned by the picker.

Here is an example:

Intent chooseFile = new Intent(Intent.ACTION_GET_CONTENT);
// Ask specifically for something that can be opened:
chooseFile.addCategory(Intent.CATEGORY_OPENABLE);
chooseFile.setType("*/*");
startActivityForResult(
        Intent.createChooser(chooseFile, "Choose a file"),
        PICKFILE_REQUEST_CODE
);

// And then somewhere, in your activity:
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == PICKFILE_REQUEST_CODE && resultCode == RESULT_OK){
        Uri content_describer = data.getData();
        BufferedReader reader = null;
        try {
            // open the user-picked file for reading:
            InputStream in = getContentResolver().openInputStream(content_describer);
            // now read the content:
            reader = new BufferedReader(new InputStreamReader(in));
            String line;
            StringBuilder builder = new StringBuilder();
            while ((line = reader.readLine()) != null){
                builder.append(line);
            }
            // Do something with the content in
            some_view.setText(builder.toString());
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

Important: Some providers (like Dropbox) store/cache their data on the external storage. You'll need to have the android.permission.READ_EXTERNAL_STORAGE-permission declared in your manifest, otherwise you'll get FileNotFoundException, even though the file is there.

---

Update: Yes, you can copy the file by reading it from one stream and writing it to another:

// Error handling is omitted for shorter code!
Uri content_describer = data.getData();
InputStream in = null;
OutputStream out = null;
try {
    // open the user-picked file for reading:
    in = getContentResolver().openInputStream(content_describer);
    // open the output-file:
    out = new FileOutputStream(new File("some/path/to/a/writable/file"));
    // copy the content:
    byte[] buffer = new byte[1024];
    int len;
    while ((len = in.read(buffer)) != -1) {
        out.write(buffer, 0, len);
    }
    // Contents are copied!
} finally {
    if (in != null) {
        in.close();
    }
    if (out != null){
        out.close();
    }
}

Deleting the file is probably not possible, since the file doesn't belong to you, it belongs to the application that shared it with yours. Therefor, the owning application is responsible for deleting the file.

回答3:

I did the same to let the user choose an image from a folder :

1) there is a button OPEN:

@Override
public void onClick(View v) {
    switch (v.getId()) {
    case R.id.btn_open:
        myOpenImagePicker();
        break;
    }
}

2) the open image folder function:

@SuppressLint("InlinedApi")
public void myOpenImagePicker() {

    if (Build.VERSION.SDK_INT < 19) {
        Intent intent = new Intent();
        intent.setType("image/*");
        intent.setAction(Intent.ACTION_GET_CONTENT);
        startActivityForResult(
                Intent.createChooser(intent, "Select Picture"),
                SELECT_FOLDER);

    } else {
        Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
        intent.addCategory(Intent.CATEGORY_OPENABLE);
        intent.setType("image/*");
        startActivityForResult(intent, SELECT_FOLDER);
    }
}

3) the activity result where i get the image file path and do whatever i want with the image path:

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    switch (requestCode) {
    case SELECT_FOLDER:
        if (resultCode == RESULT_OK && data != null) {

            Uri originalUri = data.getData();
            String id01 = W_ImgFilePathUtil.getPath(
                    getApplicationContext(), originalUri);
            Bitmap unscaledBitmap = W_ImgScalingUtil.decodeResource(id01,
                    xdrawing.getViewWidth(), xdrawing.getViewHeight(),
                    ScalingLogic.FIT);
            if (unscaledBitmap == null) {
                zprefsutil.ShowToast("IMAGE ERROR", 1);
            } else {
                setExternalScaledBitmap(W_ImgScalingUtil
                        .createScaledBitmap(unscaledBitmap,
                                xdrawing.getViewWidth(),
                                xdrawing.getViewHeight(), ScalingLogic.FIT));
                unscaledBitmap.recycle();
                xdrawing.invalidate();
            }

        }
        break;
    default:
        break;
    }
}

4) and now the MOST IMPORTANT PART, the W_ImgFilePathUtil class, the code is not from me but it allows you to retrieve the full path of any selected file be it on sd card, google drive, ...:

public class W_ImgFilePathUtil {

    /**
     * Method for return file path of Gallery image
     * 
     * @param context
     * @param uri
     * @return path of the selected image file from gallery
     */
    @SuppressLint("NewApi")
    public static String getPath(final Context context, final Uri uri) {

        // check here to KITKAT or new version
        final boolean isKitKatorUp = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;

        // DocumentProvider
        if (isKitKatorUp && DocumentsContract.isDocumentUri(context, uri)) {

            // ExternalStorageProvider
            if (isExternalStorageDocument(uri)) {
                final String docId = DocumentsContract.getDocumentId(uri);
                final String[] split = docId.split(":");
                final String type = split[0];

                if ("primary".equalsIgnoreCase(type)) {
                    return Environment.getExternalStorageDirectory() + "/"
                            + split[1];
                }
            }
            // DownloadsProvider
            else if (isDownloadsDocument(uri)) {

                final String id = DocumentsContract.getDocumentId(uri);
                final Uri contentUri = ContentUris.withAppendedId(
                        Uri.parse("content://downloads/public_downloads"),
                        Long.valueOf(id));

                return getDataColumn(context, contentUri, null, null);
            }
            // MediaProvider
            else if (isMediaDocument(uri)) {
                final String docId = DocumentsContract.getDocumentId(uri);
                final String[] split = docId.split(":");
                final String type = split[0];

                Uri contentUri = null;
                if ("image".equals(type)) {
                    contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
                } else if ("video".equals(type)) {
                    contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
                } else if ("audio".equals(type)) {
                    contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
                }

                final String selection = "_id=?";
                final String[] selectionArgs = new String[] { split[1] };

                return getDataColumn(context, contentUri, selection,
                        selectionArgs);
            }
        }

        // MediaStore (and general)
        else if ("content".equalsIgnoreCase(uri.getScheme())) {

            // Return the remote address
            if (isGooglePhotosUri(uri))
                return uri.getLastPathSegment();

            return getDataColumn(context, uri, null, null);
        }
        // File
        else if ("file".equalsIgnoreCase(uri.getScheme())) {
            return uri.getPath();
        }

        return null;
    }

    /**
     * Get the value of the data column for this Uri. This is useful for
     * MediaStore Uris, and other file-based ContentProviders.
     * 
     * @param context
     *            The context.
     * @param uri
     *            The Uri to query.
     * @param selection
     *            (Optional) Filter used in the query.
     * @param selectionArgs
     *            (Optional) Selection arguments used in the query.
     * @return The value of the _data column, which is typically a file path.
     */
    public static String getDataColumn(Context context, Uri uri,
            String selection, String[] selectionArgs) {

        Cursor cursor = null;
        final String column = "_data";
        final String[] projection = { column };

        try {
            cursor = context.getContentResolver().query(uri, projection,
                    selection, selectionArgs, null);
            if (cursor != null && cursor.moveToFirst()) {
                final int index = cursor.getColumnIndexOrThrow(column);
                return cursor.getString(index);
            }
        } finally {
            if (cursor != null)
                cursor.close();
        }
        return null;
    }

    /**
     * @param uri
     *            The Uri to check.
     * @return Whether the Uri authority is ExternalStorageProvider.
     */
    public static boolean isExternalStorageDocument(Uri uri) {
        return "com.android.externalstorage.documents".equals(uri
                .getAuthority());
    }

    /**
     * @param uri
     *            The Uri to check.
     * @return Whether the Uri authority is DownloadsProvider.
     */
    public static boolean isDownloadsDocument(Uri uri) {
        return "com.android.providers.downloads.documents".equals(uri
                .getAuthority());
    }

    /**
     * @param uri
     *            The Uri to check.
     * @return Whether the Uri authority is MediaProvider.
     */
    public static boolean isMediaDocument(Uri uri) {
        return "com.android.providers.media.documents".equals(uri
                .getAuthority());
    }

    /**
     * @param uri
     *            The Uri to check.
     * @return Whether the Uri authority is Google Photos.
     */
    public static boolean isGooglePhotosUri(Uri uri) {
        return "com.google.android.apps.photos.content".equals(uri
                .getAuthority());
    }
}

CONCLUSION : the code works with image path but sure works with any kind of file.

Hope this helps solve your problem.

PEACE.

回答4:

A Uri is not a file. A Uri is closer to a Web server URL. It is an opaque address, which only has meaning to the "server" (or in this case, the ContentProvider).

Just as you use an InputStream to read in the bytes represented by a Web URL, you use an InputStream to read in the bytes represented by the Uri. You get such a stream by calling openInputStream() on a ContentResolver.

回答5:

Pass the URI returned in onActivityResult in this method

private String getPath(Uri contentURI) {

    String result;
    Cursor cursor = getActivity().getContentResolver().query(contentURI,
            null, null, null, null);

    if (cursor == null) {
        result = contentURI.getPath();
    } else {
        cursor.moveToFirst();
        int idx = cursor
                .getColumnIndex(MediaStore.Images.ImageColumns.DATA);
        result = cursor.getString(idx);
        cursor.close();
    }
    return result;
}

回答6:

Here is how to implement a file picker and move the selected file into another location (e.g picture).

Firstly, add a file picker with a button on click listener to your code like this:

A button to pick file:

@Override
public void onClick(View v) {
    switch (v.getId()) {
    case R.id.btn_choose_file:
        showFileChooser();
        break;
    }
}

private String filePath = null;
private File sourceFile;

private static final int FILE_SELECT_CODE = 0;

    private void showFileChooser() {
        Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
        intent.setType("*/*");
        intent.addCategory(Intent.CATEGORY_OPENABLE);

        try {
            startActivityForResult(
                    Intent.createChooser(intent, "Select a File to Copy"),
                    FILE_SELECT_CODE);
        } catch (android.content.ActivityNotFoundException ex) {
            Toast.makeText(this, "Please install a File Manager.",
                    Toast.LENGTH_SHORT).show();
        }
    }

Then handle onActivityResult like this:

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        switch (requestCode) {
            case FILE_SELECT_CODE:
                if (resultCode == RESULT_OK) {
                    // Get the Uri of the selected file
                    Uri uri = data.getData();

                    File   file = new File(getCacheDir(), getFileName(uri));

                    int maxBufferSize = 1 * 1024 * 1024;

                    try {
                        InputStream inputStream = getContentResolver().openInputStream(uri);
                        Log.e("InputStream Size","Size " + inputStream);
                        int  bytesAvailable = inputStream.available();
                        int bufferSize = Math.min(bytesAvailable, maxBufferSize);
                        final byte[] buffers = new byte[bufferSize];

                        FileOutputStream outputStream = new FileOutputStream(file);
                        int read = 0;
                        while ((read = inputStream.read(buffers)) != -1) {
                            outputStream.write(buffers, 0, read);
                        }
                        Log.e("File Size","Size " + file.length());
                        inputStream.close();
                        outputStream.close();

                        file.getPath();
                        Log.e("File Path","Path " + file.getPath());
                        file.length();
                        Log.e("File Size","Size " + file.length());

                        if(file.length() > 0){

                            sourceFile = file;
                           saveFile(sourceFile);
                        }


                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                    } catch (IOException e) {
                        e.printStackTrace();
                    } catch (OutOfMemoryError e) {
                        e.printStackTrace();
                    }



                } else {


                }

                break;
        }
        super.onActivityResult(requestCode, resultCode, data);
    }





    private void saveFile (File sourceFile) {


                try {

                File currentFile = sourceFile;

                Bitmap myBitmap = BitmapFactory.decodeFile(currentFile.getAbsolutePath());


                String path = currentFile.getAbsolutePath();
                String idStr = path.substring(path.lastIndexOf('/') + 1);
                File filepath = Environment.getExternalStorageDirectory();
                File dir = new File(filepath.getAbsolutePath() + "/" + "yourFolderName" + "/");
                if (!dir.exists()) {
                    dir.mkdirs();
                }
                String fileName = currentFile.getName();
                file = new File(dir, fileName);
                if (file.exists()) file.delete();
                FileOutputStream fos = new FileOutputStream(file);
                myBitmap.compress(CompressFormat.JPEG, 65, fos);
                fos.flush();
                fos.close();


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

    }

Note: Don't forget to add this permission to the manifest file.

    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Hope this helps.