BluetoothSocket
class BluetoothSocket : Closeable
| kotlin.Any | |
| ↳ | android.bluetooth.BluetoothSocket |
A connected or connecting Bluetooth socket.
The interface for Bluetooth Sockets is similar to that of TCP sockets: java.net.Socket and java.net.ServerSocket. On the server side, use a BluetoothServerSocket to create a listening server socket. When a connection is accepted by the BluetoothServerSocket, it will return a new BluetoothSocket to manage the connection. On the client side, use a single BluetoothSocket to both initiate an outgoing connection and to manage the connection.
The most common type of Bluetooth socket is RFCOMM, which is the type supported by the Android APIs. RFCOMM is a connection-oriented, streaming transport over Bluetooth. It is also known as the Serial Port Profile (SPP).
To create a BluetoothSocket for connecting to a known device, use BluetoothDevice.createRfcommSocketToServiceRecord(). Then call connect() to attempt a connection to the remote device. This call will block until a connection is established or the connection fails.
To create a BluetoothSocket as a server (or "host"), see the BluetoothServerSocket documentation.
Once the socket is connected, whether initiated as a client or accepted as a server, open the IO streams by calling getInputStream and getOutputStream in order to retrieve java.io.InputStream and java.io.OutputStream objects, respectively, which are automatically connected to the socket.
BluetoothSocket is thread safe. In particular, #close will always immediately abort ongoing operations and close the socket.
Summary
| Constants | |
|---|---|
| static Int |
L2CAP socket |
| static Int |
RFCOMM socket |
| static Int |
SCO socket |
| Public methods | |
|---|---|
| Unit |
close() |
| Unit |
connect()Attempt to connect to a remote device. |
| Int |
Get the type of the underlying connection. |
| InputStream! |
Get the input stream associated with this socket. |
| Int |
Get the maximum supported Receive packet size for the underlying transport. |
| Int |
Get the maximum supported Transmit packet size for the underlying transport. |
| OutputStream! |
Get the output stream associated with this socket. |
| BluetoothDevice! |
Get the remote device this socket is connecting, or connected, to. |
| Boolean |
Get the connection status of this socket, ie, whether there is an active connection with remote device. |
| String |
toString() |
Constants
Public methods
close
fun close(): Unit
| Exceptions | |
|---|---|
java.lang.Exception |
if this resource cannot be closed |
java.io.IOException |
if an I/O error occurs |
connect
fun connect(): Unit
Attempt to connect to a remote device.
This method will block until a connection is made or the connection fails. If this method returns without an exception then this socket is now connected.
Creating new connections to remote Bluetooth devices should not be attempted while device discovery is in progress. Device discovery is a heavyweight procedure on the Bluetooth adapter and will significantly slow a device connection. Use android.bluetooth.BluetoothAdapter#cancelDiscovery() to cancel an ongoing discovery. Discovery is not managed by the Activity, but is run as a system service, so an application should always call android.bluetooth.BluetoothAdapter#cancelDiscovery() even if it did not directly request a discovery, just to be sure.
close can be used to abort this call from another thread.
For apps targeting Build.VERSION_CODES.S or or higher, this requires the Manifest.permission.BLUETOOTH_CONNECT permission which can be gained with android.app.Activity#requestPermissions(String[], int).
Requires android.Manifest.permission#BLUETOOTH_CONNECT
| Exceptions | |
|---|---|
android.bluetooth.BluetoothSocketException |
in case of failure, with the corresponding error code. |
java.io.IOException |
for other errors (eg: InputStream read failures etc.). |
getConnectionType
fun getConnectionType(): Int
Get the type of the underlying connection.
| Return | |
|---|---|
Int |
one of TYPE_RFCOMM, TYPE_SCO or TYPE_L2CAP |
getInputStream
fun getInputStream(): InputStream!
Get the input stream associated with this socket.
The input stream will be returned even if the socket is not yet connected, but operations on that stream will throw IOException until the associated socket is connected.
| Return | |
|---|---|
InputStream! |
InputStream |
getMaxReceivePacketSize
fun getMaxReceivePacketSize(): Int
Get the maximum supported Receive packet size for the underlying transport. Use this to optimize the reads done on the input stream, as any call to read will return a maximum of this amount of bytes - or for some transports a multiple of this value.
| Return | |
|---|---|
Int |
the maximum supported Receive packet size for the underlying transport. |
getMaxTransmitPacketSize
fun getMaxTransmitPacketSize(): Int
Get the maximum supported Transmit packet size for the underlying transport. Use this to optimize the writes done to the output socket, to avoid sending half full packets.
| Return | |
|---|---|
Int |
the maximum supported Transmit packet size for the underlying transport. |
getOutputStream
fun getOutputStream(): OutputStream!
Get the output stream associated with this socket.
The output stream will be returned even if the socket is not yet connected, but operations on that stream will throw IOException until the associated socket is connected.
| Return | |
|---|---|
OutputStream! |
OutputStream |
getRemoteDevice
fun getRemoteDevice(): BluetoothDevice!
Get the remote device this socket is connecting, or connected, to.
| Return | |
|---|---|
BluetoothDevice! |
remote device |
isConnected
fun isConnected(): Boolean
Get the connection status of this socket, ie, whether there is an active connection with remote device.
| Return | |
|---|---|
Boolean |
true if connected false if not connected |
toString
fun toString(): String
| Return | |
|---|---|
String |
a string representation of the object. |