Android APIs
public final class

BluetoothSocket

extends Object
implements Closeable
java.lang.Object
   ↳ android.bluetooth.BluetoothSocket

Class Overview

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.

Note: Requires the BLUETOOTH permission.

Developer Guides

For more information about using Bluetooth, read the Bluetooth developer guide.

Summary

Public Methods
void close()
Closes the object and release any system resources it holds.
void connect()
Attempt to connect to a remote device.
InputStream getInputStream()
Get the input stream associated with this socket.
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.
[Expand]
Inherited Methods
From class java.lang.Object
From interface java.io.Closeable
From interface java.lang.AutoCloseable

Public Methods

public void close ()

Added in API level 5

Closes the object and release any system resources it holds.

Although only the first call has any effect, it is safe to call close multiple times on the same object. This is more lenient than the overridden AutoCloseable.close(), which may be called at most once.

Throws
IOException

public void connect ()

Added in API level 5

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 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 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.

Throws
IOException on error, for example connection failure

public InputStream getInputStream ()

Added in API level 5

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
Throws
IOException

public OutputStream getOutputStream ()

Added in API level 5

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
Throws
IOException

public BluetoothDevice getRemoteDevice ()

Added in API level 5

Get the remote device this socket is connecting, or connected, to.

Returns
  • remote device

public boolean isConnected ()

Added in API level 14

Get the connection status of this socket, ie, whether there is an active connection with remote device.

Returns
  • true if connected false if not connected