Bluetooth file transfer in Android

Question

I am developing an app in which I need to transfer data in file between two devices.

I have seen tutorial regarding Bluetooth chat but can't figure out what stuff needed for file transfer. How can I do this?

Please refer following article, It shows how to use native bluetooth application to send file. http://kpbird.blogspot.com/2011/04/android-send-image-via-bluetooth.html — Ketan Parmar, May 17 '11 at 04:40

score 6 · Answer 1 · answered May 26 '17 at 11:25

Today i had the same task & after spending couple of hours i'd achieved this. I'm posting the whole code so someone else can easily understand this. This is my Activity:

package com.aqua.bluetoothfiletransfer.indragni;

import java.io.File;
import java.util.List;

import android.Manifest;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.content.ContentUris;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.database.Cursor;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.provider.DocumentsContract;
import android.provider.MediaStore;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import com.aqua.bluetoothfiletransfer.R;


public class MainActivity extends AppCompatActivity {

    private static final int DISCOVER_DURATION = 300;
    private static final int REQUEST_BLU = 1;

    String path;

    private static final String[] INITIAL_PERMS = {Manifest.permission.WRITE_EXTERNAL_STORAGE,
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.READ_CONTACTS,
            Manifest.permission.WRITE_CONTACTS,
            Manifest.permission.CAMERA,
            Manifest.permission.ACCESS_FINE_LOCATION};

    private static final int INITIAL_REQUEST = 1337;

    private static final int REQUEST_WRITE_STORAGE = INITIAL_REQUEST + 4;

    TextView textView_FileName;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_mainn);
        textView_FileName = (TextView) findViewById(R.id.textView_FileName);

        if (!canAccessLocation() || !canAccessCamera() || !canAccessWriteStorage() || !canAccessReadStorage() || !canAccessReadContacts() || !canAccessWriteContacts()) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                requestPermissions(INITIAL_PERMS, INITIAL_REQUEST);
            }
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {

        switch (requestCode) {

            case REQUEST_WRITE_STORAGE:
                if (canAccessWriteStorage()) {
                    //reload my activity with permission granted or use the features what required the permission
                    System.out.println("permission grantedddd");

                } else {
                    Toast.makeText(this, "The app was not allowed to write to your storage. Hence, it cannot function properly. Please consider granting it this permission", Toast.LENGTH_LONG).show();
                }
                break;
        }
    }

    public void sendViaBluetooth(View v) {
        if (path == null) {
            Toast.makeText(this, "Please select file first", Toast.LENGTH_SHORT).show();
            return;
        }

        BluetoothAdapter btAdapter = BluetoothAdapter.getDefaultAdapter();

        if (btAdapter == null) {
            Toast.makeText(this, "Bluetooth is not supported on this device", Toast.LENGTH_LONG).show();
        } else {
            enableBluetooth();
        }
    }

    public void getFile(View v) {
        Intent mediaIntent = new Intent(Intent.ACTION_GET_CONTENT);
        mediaIntent.setType("*/*"); //set mime type as per requirement
        startActivityForResult(mediaIntent, 1001);
    }

    public void enableBluetooth() {
        Intent discoveryIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
        discoveryIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, DISCOVER_DURATION);
        startActivityForResult(discoveryIntent, REQUEST_BLU);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {

        if (resultCode == DISCOVER_DURATION && requestCode == REQUEST_BLU) {

            Intent intent = new Intent();
            intent.setAction(Intent.ACTION_SEND);
            intent.setType("*/*");

            File f = new File(path);
            intent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(f));

            PackageManager pm = getPackageManager();
            List<ResolveInfo> appsList = pm.queryIntentActivities(intent, 0);

            if (appsList.size() > 0) {
                String packageName = null;
                String className = null;
                boolean found = false;

                for (ResolveInfo info : appsList) {
                    packageName = info.activityInfo.packageName;
                    if (packageName.equals("com.android.bluetooth")) {
                        className = info.activityInfo.name;
                        found = true;
                        break;
                    }
                }

                if (!found) {
                    Toast.makeText(this, "Bluetooth havn't been found",
                            Toast.LENGTH_LONG).show();
                } else {
                    intent.setClassName(packageName, className);
                    startActivity(intent);
                }
            }
        } else if (requestCode == 1001
                && resultCode == Activity.RESULT_OK) {
            Uri uriPath = data.getData();
            Log.d("", "Video URI= " + uriPath);

            path = getPath(this, uriPath);// "/mnt/sdcard/FileName.mp3"
            System.out.println("pathhhh " + path);
            textView_FileName.setText(path);

        } else {
            Toast.makeText(this, "Bluetooth is cancelled", Toast.LENGTH_LONG)
                    .show();
        }
    }

    private boolean canAccessWriteStorage() {
        return (hasPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE));
    }

    private boolean canAccessReadStorage() {
        return (hasPermission(Manifest.permission.READ_EXTERNAL_STORAGE));
    }

    private boolean canAccessReadContacts() {
        return (hasPermission(Manifest.permission.READ_CONTACTS));
    }

    private boolean canAccessWriteContacts() {
        return (hasPermission(Manifest.permission.WRITE_CONTACTS));
    }

    private boolean canAccessCamera() {
        return (hasPermission(Manifest.permission.CAMERA));
    }

    private boolean canAccessLocation() {
        return (hasPermission(Manifest.permission.ACCESS_FINE_LOCATION));
    }

    private boolean hasPermission(String perm) {
        return (PackageManager.PERMISSION_GRANTED == ContextCompat.checkSelfPermission(this, perm));
    }

    public static String getPath(final Context context, final Uri uri) {
        final boolean isKitKatOrAbove = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;

        // DocumentProvider
        if (isKitKatOrAbove && 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];
                }

                // TODO handle non-primary volumes
            }
            // 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 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 column_index = cursor.getColumnIndexOrThrow(column);
                return cursor.getString(column_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());
    }

}

This is my layout:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center_horizontal"
    android:orientation="vertical">

    <TextView
        android:id="@+id/textView_FileName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="50dp"
        android:text="Please select file"
        android:textSize="18sp" />


    <Button
        android:id="@+id/button_GetFile"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="getFile"
        android:text="Get file from device" />

    <Button
        android:id="@+id/button_SendFile"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="sendViaBluetooth"
        android:text="Send via Bluetooth" />

</LinearLayout>

Last step is please declare all the permissions in manifest:

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

That's it.

score 1 · Answer 2 · edited Nov 17 '19 at 12:51

1

File transfer is same like you send message. First you convert file to input stream and then transfer this to founded device.

edited Nov 17 '19 at 12:51

halfer

19,824
17
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answered Feb 01 '11 at 13:27

milan manvar

238
2
11

communication protocol will be the same but if the File size is larger than 40-50MB then there should be a different protocol for input stream and output stream. – ahmednawazCS Feb 04 '21 at 07:37

score 0 · Answer 3 · edited Nov 02 '18 at 01:45

0

Intent intent = new Intent();  
intent.setAction(Intent.ACTION_SEND);  
intent.setType("image/*");

String uri = "/mnt/sdcard/test.jpg";
intent.putExtra(Intent.EXTRA_STREAM, Uri.fromFile(new File(uri)));
startActivity(intent);

Please set this code in your button and set uri to file path then press button your file will be transferred.

edited Nov 02 '18 at 01:45

Pang

9,564
146
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answered Dec 15 '12 at 04:58

haresh

321
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score 0 · Answer 4 · answered Feb 01 '11 at 13:33

0

Something like this:

        String addr = args[0];
        log("Connecting over bluetooth to " + addr);

        bs = null;
        try {
            BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(addr);
            mBluetoothAdapter.cancelDiscovery();

            Method m = device.getClass().getMethod("createRfcommSocket", new Class[] {int.class});
            bs = (BluetoothSocket) m.invoke(device, Integer.valueOf(1));
            bs.connect();
        } catch (Exception e) {
            return false;
        }

You need the MAC address of the device to which you are going to connect, and then just use the InputStream and OutputStream of bs.

answered Feb 01 '11 at 13:33

gnclmorais

4,897
5
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Any particular reason why we need to use createRfcommSocket() through reflection ?? can't we avoid this ? – Gem Dec 08 '16 at 11:05
1

this only connects to the device but doesn't transfer any data – Emmanuel BRUNET Dec 14 '16 at 08:10
No Its not that simple as it look. How the receiving device(eg windows PC) knows that the incoming stream of data is actually a file of certain type. The file could be png or mp4 etc. Also how the receiving device will actually convert that input instream and then save it by its own? As far as my i research on this, we need to implement OBEX to achieve this. – Gem Dec 21 '16 at 18:59

Bluetooth file transfer in Android

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