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public
final
class
BluetoothSocket
extends Object
implements
Closeable
java.lang.Object | |
↳ | android.bluetooth.BluetoothSocket |
A connected or connecting Bluetooth socket.
The interface for Bluetooth Sockets is similar to that of TCP sockets:
Socket
and 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 InputStream
and 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.
For more information about using Bluetooth, read the Bluetooth developer guide.
Constants | |
---|---|
int |
TYPE_L2CAP
L2CAP socket |
int |
TYPE_RFCOMM
RFCOMM socket |
int |
TYPE_SCO
SCO socket |
Public methods | |
---|---|
void
|
close()
Closes this stream and releases any system resources associated with it. |
void
|
connect()
Attempt to connect to a remote device. |
int
|
getConnectionType()
Get the type of the underlying connection. |
InputStream
|
getInputStream()
Get the input stream associated with this socket. |
int
|
getMaxReceivePacketSize()
Get the maximum supported Receive packet size for the underlying transport. |
int
|
getMaxTransmitPacketSize()
Get the maximum supported Transmit packet size for the underlying transport. |
OutputStream
|
getOutputStream()
Get the output stream associated with this socket. |
BluetoothDevice
|
getRemoteDevice()
Get the remote device this socket is connecting, or connected, to. |
boolean
|
isConnected()
Get the connection status of this socket, ie, whether there is an active connection with remote device. |
Inherited methods | |
---|---|
public static final int TYPE_L2CAP
L2CAP socket
Constant Value: 3 (0x00000003)
public static final int TYPE_RFCOMM
RFCOMM socket
Constant Value: 1 (0x00000001)
public static final int TYPE_SCO
SCO socket
Constant Value: 2 (0x00000002)
public void close ()
Closes this stream and releases any system resources associated with it. If the stream is already closed then invoking this method has no effect.
As noted in AutoCloseable#close()
, cases where the
close may fail require careful attention. It is strongly advised
to relinquish the underlying resources and to internally
mark the Closeable
as closed, prior to throwing
the IOException
.
Throws | |
---|---|
IOException |
public void connect ()
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 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
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
Activity.requestPermissions(String[], int)
.
Requires Manifest.permission.BLUETOOTH_CONNECT
Throws | |
---|---|
IOException |
on error, for example connection failure |
public int getConnectionType ()
Get the type of the underlying connection.
Returns | |
---|---|
int |
one of TYPE_RFCOMM , TYPE_SCO or TYPE_L2CAP |
public InputStream getInputStream ()
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.
Returns | |
---|---|
InputStream |
InputStream |
Throws | |
---|---|
IOException |
public int getMaxReceivePacketSize ()
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.
Returns | |
---|---|
int |
the maximum supported Receive packet size for the underlying transport. |
public int getMaxTransmitPacketSize ()
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.
Returns | |
---|---|
int |
the maximum supported Transmit packet size for the underlying transport. |
public OutputStream getOutputStream ()
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.
Returns | |
---|---|
OutputStream |
OutputStream |
Throws | |
---|---|
IOException |
public BluetoothDevice getRemoteDevice ()
Get the remote device this socket is connecting, or connected, to.
Returns | |
---|---|
BluetoothDevice |
remote device |
public boolean isConnected ()
Get the connection status of this socket, ie, whether there is an active connection with remote device.
Returns | |
---|---|
boolean |
true if connected false if not connected |