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Android example source code file (BluetoothAdapter.java)

This example Android source code file (BluetoothAdapter.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

address_length, android, annotate, annotations, bluetoothadapter, bluetoothserversocket, dbg, ibluetooth, io, ioexception, linkedlist, os, remoteexception, rfcommchannelpicker, scan_mode_none, set, state_off, string, util, uuid

The BluetoothAdapter.java Android example source code

/*
 * Copyright (C) 2009 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.bluetooth;

import android.annotation.SdkConstant;
import android.annotation.SdkConstant.SdkConstantType;
import android.os.Binder;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.ParcelUuid;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.util.Log;

import java.io.IOException;
import java.util.Collections;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Random;
import java.util.Set;
import java.util.UUID;

/**
 * Represents the local device Bluetooth adapter. The {@link BluetoothAdapter}
 * lets you perform fundamental Bluetooth tasks, such as initiate
 * device discovery, query a list of bonded (paired) devices,
 * instantiate a {@link BluetoothDevice} using a known MAC address, and create
 * a {@link BluetoothServerSocket} to listen for connection requests from other
 * devices.
 *
 * <p>To get a {@link BluetoothAdapter} representing the local Bluetooth
 * adapter, call the static {@link #getDefaultAdapter} method.
 * Fundamentally, this is your starting point for all
 * Bluetooth actions. Once you have the local adapter, you can get a set of
 * {@link BluetoothDevice} objects representing all paired devices with
 * {@link #getBondedDevices()}; start device discovery with
 * {@link #startDiscovery()}; or create a {@link BluetoothServerSocket} to
 * listen for incoming connection requests with
 * {@link #listenUsingRfcommWithServiceRecord(String,UUID)}.
 *
 * <p class="note">Note:
 * Most methods require the {@link android.Manifest.permission#BLUETOOTH}
 * permission and some also require the
 * {@link android.Manifest.permission#BLUETOOTH_ADMIN} permission.
 *
 * {@see BluetoothDevice}
 * {@see BluetoothServerSocket}
 */
public final class BluetoothAdapter {
    private static final String TAG = "BluetoothAdapter";
    private static final boolean DBG = false;

    /**
     * Sentinel error value for this class. Guaranteed to not equal any other
     * integer constant in this class. Provided as a convenience for functions
     * that require a sentinel error value, for example:
     * <p>Intent.getIntExtra(BluetoothAdapter.EXTRA_STATE,
     * BluetoothAdapter.ERROR)</code>
     */
    public static final int ERROR = Integer.MIN_VALUE;

    /**
     * Broadcast Action: The state of the local Bluetooth adapter has been
     * changed.
     * <p>For example, Bluetooth has been turned on or off.
     * <p>Always contains the extra fields {@link #EXTRA_STATE} and {@link
     * #EXTRA_PREVIOUS_STATE} containing the new and old states
     * respectively.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH} to receive.
     */
    @SdkConstant(SdkConstantType.BROADCAST_INTENT_ACTION)
    public static final String ACTION_STATE_CHANGED =
            "android.bluetooth.adapter.action.STATE_CHANGED";

    /**
     * Used as an int extra field in {@link #ACTION_STATE_CHANGED}
     * intents to request the current power state. Possible values are:
     * {@link #STATE_OFF},
     * {@link #STATE_TURNING_ON},
     * {@link #STATE_ON},
     * {@link #STATE_TURNING_OFF},
     */
    public static final String EXTRA_STATE =
            "android.bluetooth.adapter.extra.STATE";
    /**
     * Used as an int extra field in {@link #ACTION_STATE_CHANGED}
     * intents to request the previous power state. Possible values are:
     * {@link #STATE_OFF},
     * {@link #STATE_TURNING_ON},
     * {@link #STATE_ON},
     * {@link #STATE_TURNING_OFF},
     */
    public static final String EXTRA_PREVIOUS_STATE =
            "android.bluetooth.adapter.extra.PREVIOUS_STATE";

    /**
     * Indicates the local Bluetooth adapter is off.
     */
    public static final int STATE_OFF = 10;
    /**
     * Indicates the local Bluetooth adapter is turning on. However local
     * clients should wait for {@link #STATE_ON} before attempting to
     * use the adapter.
     */
    public static final int STATE_TURNING_ON = 11;
    /**
     * Indicates the local Bluetooth adapter is on, and ready for use.
     */
    public static final int STATE_ON = 12;
    /**
     * Indicates the local Bluetooth adapter is turning off. Local clients
     * should immediately attempt graceful disconnection of any remote links.
     */
    public static final int STATE_TURNING_OFF = 13;

    /**
     * Activity Action: Show a system activity that requests discoverable mode.
     * This activity will also request the user to turn on Bluetooth if it
     * is not currently enabled.
     * <p>Discoverable mode is equivalent to {@link
     * #SCAN_MODE_CONNECTABLE_DISCOVERABLE}. It allows remote devices to see
     * this Bluetooth adapter when they perform a discovery.
     * <p>For privacy, Android is not discoverable by default.
     * <p>The sender of this Intent can optionally use extra field {@link
     * #EXTRA_DISCOVERABLE_DURATION} to request the duration of
     * discoverability. Currently the default duration is 120 seconds, and
     * maximum duration is capped at 300 seconds for each request.
     * <p>Notification of the result of this activity is posted using the
     * {@link android.app.Activity#onActivityResult} callback. The
     * <code>resultCode
     * will be the duration (in seconds) of discoverability or
     * {@link android.app.Activity#RESULT_CANCELED} if the user rejected
     * discoverability or an error has occurred.
     * <p>Applications can also listen for {@link #ACTION_SCAN_MODE_CHANGED}
     * for global notification whenever the scan mode changes. For example, an
     * application can be notified when the device has ended discoverability.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH}
     */
    @SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION)
    public static final String ACTION_REQUEST_DISCOVERABLE =
            "android.bluetooth.adapter.action.REQUEST_DISCOVERABLE";

    /**
     * Used as an optional int extra field in {@link
     * #ACTION_REQUEST_DISCOVERABLE} intents to request a specific duration
     * for discoverability in seconds. The current default is 120 seconds, and
     * requests over 300 seconds will be capped. These values could change.
     */
    public static final String EXTRA_DISCOVERABLE_DURATION =
            "android.bluetooth.adapter.extra.DISCOVERABLE_DURATION";

    /**
     * Activity Action: Show a system activity that allows the user to turn on
     * Bluetooth.
     * <p>This system activity will return once Bluetooth has completed turning
     * on, or the user has decided not to turn Bluetooth on.
     * <p>Notification of the result of this activity is posted using the
     * {@link android.app.Activity#onActivityResult} callback. The
     * <code>resultCode
     * will be {@link android.app.Activity#RESULT_OK} if Bluetooth has been
     * turned on or {@link android.app.Activity#RESULT_CANCELED} if the user
     * has rejected the request or an error has occurred.
     * <p>Applications can also listen for {@link #ACTION_STATE_CHANGED}
     * for global notification whenever Bluetooth is turned on or off.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH}
     */
    @SdkConstant(SdkConstantType.ACTIVITY_INTENT_ACTION)
    public static final String ACTION_REQUEST_ENABLE =
            "android.bluetooth.adapter.action.REQUEST_ENABLE";

    /**
     * Broadcast Action: Indicates the Bluetooth scan mode of the local Adapter
     * has changed.
     * <p>Always contains the extra fields {@link #EXTRA_SCAN_MODE} and {@link
     * #EXTRA_PREVIOUS_SCAN_MODE} containing the new and old scan modes
     * respectively.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH}
     */
    @SdkConstant(SdkConstantType.BROADCAST_INTENT_ACTION)
    public static final String ACTION_SCAN_MODE_CHANGED =
            "android.bluetooth.adapter.action.SCAN_MODE_CHANGED";

    /**
     * Used as an int extra field in {@link #ACTION_SCAN_MODE_CHANGED}
     * intents to request the current scan mode. Possible values are:
     * {@link #SCAN_MODE_NONE},
     * {@link #SCAN_MODE_CONNECTABLE},
     * {@link #SCAN_MODE_CONNECTABLE_DISCOVERABLE},
     */
    public static final String EXTRA_SCAN_MODE = "android.bluetooth.adapter.extra.SCAN_MODE";
    /**
     * Used as an int extra field in {@link #ACTION_SCAN_MODE_CHANGED}
     * intents to request the previous scan mode. Possible values are:
     * {@link #SCAN_MODE_NONE},
     * {@link #SCAN_MODE_CONNECTABLE},
     * {@link #SCAN_MODE_CONNECTABLE_DISCOVERABLE},
     */
    public static final String EXTRA_PREVIOUS_SCAN_MODE =
            "android.bluetooth.adapter.extra.PREVIOUS_SCAN_MODE";

    /**
     * Indicates that both inquiry scan and page scan are disabled on the local
     * Bluetooth adapter. Therefore this device is neither discoverable
     * nor connectable from remote Bluetooth devices.
     */
    public static final int SCAN_MODE_NONE = 20;
    /**
     * Indicates that inquiry scan is disabled, but page scan is enabled on the
     * local Bluetooth adapter. Therefore this device is not discoverable from
     * remote Bluetooth devices, but is connectable from remote devices that
     * have previously discovered this device.
     */
    public static final int SCAN_MODE_CONNECTABLE = 21;
    /**
     * Indicates that both inquiry scan and page scan are enabled on the local
     * Bluetooth adapter. Therefore this device is both discoverable and
     * connectable from remote Bluetooth devices.
     */
    public static final int SCAN_MODE_CONNECTABLE_DISCOVERABLE = 23;


    /**
     * Broadcast Action: The local Bluetooth adapter has started the remote
     * device discovery process.
     * <p>This usually involves an inquiry scan of about 12 seconds, followed
     * by a page scan of each new device to retrieve its Bluetooth name.
     * <p>Register for {@link BluetoothDevice#ACTION_FOUND} to be notified as
     * remote Bluetooth devices are found.
     * <p>Device discovery is a heavyweight procedure. New connections to
     * remote Bluetooth devices should not be attempted while discovery is in
     * progress, and existing connections will experience limited bandwidth
     * and high latency. Use {@link #cancelDiscovery()} to cancel an ongoing
     * discovery.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH} to receive.
     */
    @SdkConstant(SdkConstantType.BROADCAST_INTENT_ACTION)
    public static final String ACTION_DISCOVERY_STARTED =
            "android.bluetooth.adapter.action.DISCOVERY_STARTED";
    /**
     * Broadcast Action: The local Bluetooth adapter has finished the device
     * discovery process.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH} to receive.
     */
    @SdkConstant(SdkConstantType.BROADCAST_INTENT_ACTION)
    public static final String ACTION_DISCOVERY_FINISHED =
            "android.bluetooth.adapter.action.DISCOVERY_FINISHED";

    /**
     * Broadcast Action: The local Bluetooth adapter has changed its friendly
     * Bluetooth name.
     * <p>This name is visible to remote Bluetooth devices.
     * <p>Always contains the extra field {@link #EXTRA_LOCAL_NAME} containing
     * the name.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH} to receive.
     */
    @SdkConstant(SdkConstantType.BROADCAST_INTENT_ACTION)
    public static final String ACTION_LOCAL_NAME_CHANGED =
            "android.bluetooth.adapter.action.LOCAL_NAME_CHANGED";
    /**
     * Used as a String extra field in {@link #ACTION_LOCAL_NAME_CHANGED}
     * intents to request the local Bluetooth name.
     */
    public static final String EXTRA_LOCAL_NAME = "android.bluetooth.adapter.extra.LOCAL_NAME";

    /** @hide */
    public static final String BLUETOOTH_SERVICE = "bluetooth";

    private static final int ADDRESS_LENGTH = 17;

    /**
     * Lazyily initialized singleton. Guaranteed final after first object
     * constructed.
     */
    private static BluetoothAdapter sAdapter;

    private final IBluetooth mService;

    /**
     * Get a handle to the default local Bluetooth adapter.
     * <p>Currently Android only supports one Bluetooth adapter, but the API
     * could be extended to support more. This will always return the default
     * adapter.
     * @return the default local adapter, or null if Bluetooth is not supported
     *         on this hardware platform
     */
    public static synchronized BluetoothAdapter getDefaultAdapter() {
        if (sAdapter == null) {
            IBinder b = ServiceManager.getService(BluetoothAdapter.BLUETOOTH_SERVICE);
            if (b != null) {
                IBluetooth service = IBluetooth.Stub.asInterface(b);
                sAdapter = new BluetoothAdapter(service);
            }
        }
        return sAdapter;
    }

    /**
     * Use {@link #getDefaultAdapter} to get the BluetoothAdapter instance.
     * @hide
     */
    public BluetoothAdapter(IBluetooth service) {
        if (service == null) {
            throw new IllegalArgumentException("service is null");
        }
        mService = service;
    }

    /**
     * Get a {@link BluetoothDevice} object for the given Bluetooth hardware
     * address.
     * <p>Valid Bluetooth hardware addresses must be upper case, in a format
     * such as "00:11:22:33:AA:BB". The helper {@link #checkBluetoothAddress} is
     * available to validate a Bluetooth address.
     * <p>A {@link BluetoothDevice} will always be returned for a valid
     * hardware address, even if this adapter has never seen that device.
     *
     * @param address valid Bluetooth MAC address
     * @throws IllegalArgumentException if address is invalid
     */
    public BluetoothDevice getRemoteDevice(String address) {
        return new BluetoothDevice(address);
    }

    /**
     * Return true if Bluetooth is currently enabled and ready for use.
     * <p>Equivalent to:
     * <code>getBluetoothState() == STATE_ON
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH}
     *
     * @return true if the local adapter is turned on
     */
    public boolean isEnabled() {
        try {
            return mService.isEnabled();
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return false;
    }

    /**
     * Get the current state of the local Bluetooth adapter.
     * <p>Possible return values are
     * {@link #STATE_OFF},
     * {@link #STATE_TURNING_ON},
     * {@link #STATE_ON},
     * {@link #STATE_TURNING_OFF}.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH}
     *
     * @return current state of Bluetooth adapter
     */
    public int getState() {
        try {
            return mService.getBluetoothState();
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return STATE_OFF;
    }

    /**
     * Turn on the local Bluetooth adapter—do not use without explicit
     * user action to turn on Bluetooth.
     * <p>This powers on the underlying Bluetooth hardware, and starts all
     * Bluetooth system services.
     * <p class="caution">Bluetooth should never be enabled without
     * direct user consent</strong>. If you want to turn on Bluetooth in order
     * to create a wireless connection, you should use the {@link
     * #ACTION_REQUEST_ENABLE} Intent, which will raise a dialog that requests
     * user permission to turn on Bluetooth. The {@link #enable()} method is
     * provided only for applications that include a user interface for changing
     * system settings, such as a "power manager" app.</p>
     * <p>This is an asynchronous call: it will return immediately, and
     * clients should listen for {@link #ACTION_STATE_CHANGED}
     * to be notified of subsequent adapter state changes. If this call returns
     * true, then the adapter state will immediately transition from {@link
     * #STATE_OFF} to {@link #STATE_TURNING_ON}, and some time
     * later transition to either {@link #STATE_OFF} or {@link
     * #STATE_ON}. If this call returns false then there was an
     * immediate problem that will prevent the adapter from being turned on -
     * such as Airplane mode, or the adapter is already turned on.
     * <p>Requires the {@link android.Manifest.permission#BLUETOOTH_ADMIN}
     * permission
     *
     * @return true to indicate adapter startup has begun, or false on
     *         immediate error
     */
    public boolean enable() {
        try {
            return mService.enable();
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return false;
    }

    /**
     * Turn off the local Bluetooth adapter—do not use without explicit
     * user action to turn off Bluetooth.
     * <p>This gracefully shuts down all Bluetooth connections, stops Bluetooth
     * system services, and powers down the underlying Bluetooth hardware.
     * <p class="caution">Bluetooth should never be disbled without
     * direct user consent</strong>. The {@link #disable()} method is
     * provided only for applications that include a user interface for changing
     * system settings, such as a "power manager" app.</p>
     * <p>This is an asynchronous call: it will return immediately, and
     * clients should listen for {@link #ACTION_STATE_CHANGED}
     * to be notified of subsequent adapter state changes. If this call returns
     * true, then the adapter state will immediately transition from {@link
     * #STATE_ON} to {@link #STATE_TURNING_OFF}, and some time
     * later transition to either {@link #STATE_OFF} or {@link
     * #STATE_ON}. If this call returns false then there was an
     * immediate problem that will prevent the adapter from being turned off -
     * such as the adapter already being turned off.
     * <p>Requires the {@link android.Manifest.permission#BLUETOOTH_ADMIN}
     * permission
     *
     * @return true to indicate adapter shutdown has begun, or false on
     *         immediate error
     */
    public boolean disable() {
        try {
            return mService.disable(true);
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return false;
    }

    /**
     * Returns the hardware address of the local Bluetooth adapter.
     * <p>For example, "00:11:22:AA:BB:CC".
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH}
     *
     * @return Bluetooth hardware address as string
     */
    public String getAddress() {
        try {
            return mService.getAddress();
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return null;
    }

    /**
     * Get the friendly Bluetooth name of the local Bluetooth adapter.
     * <p>This name is visible to remote Bluetooth devices.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH}
     *
     * @return the Bluetooth name, or null on error
     */
    public String getName() {
        try {
            return mService.getName();
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return null;
    }

    /**
     * Set the friendly Bluetooth name of the local Bluetoth adapter.
     * <p>This name is visible to remote Bluetooth devices.
     * <p>Valid Bluetooth names are a maximum of 248 UTF-8 characters, however
     * many remote devices can only display the first 40 characters, and some
     * may be limited to just 20.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH_ADMIN}
     *
     * @param name a valid Bluetooth name
     * @return     true if the name was set, false otherwise
     */
    public boolean setName(String name) {
        try {
            return mService.setName(name);
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return false;
    }

    /**
     * Get the current Bluetooth scan mode of the local Bluetooth adaper.
     * <p>The Bluetooth scan mode determines if the local adapter is
     * connectable and/or discoverable from remote Bluetooth devices.
     * <p>Possible values are:
     * {@link #SCAN_MODE_NONE},
     * {@link #SCAN_MODE_CONNECTABLE},
     * {@link #SCAN_MODE_CONNECTABLE_DISCOVERABLE}.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH}
     *
     * @return scan mode
     */
    public int getScanMode() {
        try {
            return mService.getScanMode();
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return SCAN_MODE_NONE;
    }

    /**
     * Set the Bluetooth scan mode of the local Bluetooth adapter.
     * <p>The Bluetooth scan mode determines if the local adapter is
     * connectable and/or discoverable from remote Bluetooth devices.
     * <p>For privacy reasons, discoverable mode is automatically turned off
     * after <code>duration seconds. For example, 120 seconds should be
     * enough for a remote device to initiate and complete its discovery
     * process.
     * <p>Valid scan mode values are:
     * {@link #SCAN_MODE_NONE},
     * {@link #SCAN_MODE_CONNECTABLE},
     * {@link #SCAN_MODE_CONNECTABLE_DISCOVERABLE}.
     * <p>Requires {@link android.Manifest.permission#WRITE_SECURE_SETTINGS}
     * <p>Applications cannot set the scan mode. They should use
     * <code>startActivityForResult(
     * BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE})
     * </code>instead.
     *
     * @param mode valid scan mode
     * @param duration time in seconds to apply scan mode, only used for
     *                 {@link #SCAN_MODE_CONNECTABLE_DISCOVERABLE}
     * @return     true if the scan mode was set, false otherwise
     * @hide
     */
    public boolean setScanMode(int mode, int duration) {
        try {
            return mService.setScanMode(mode, duration);
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return false;
    }

    /** @hide */
    public boolean setScanMode(int mode) {
        return setScanMode(mode, 120);
    }

    /** @hide */
    public int getDiscoverableTimeout() {
        try {
            return mService.getDiscoverableTimeout();
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return -1;
    }

    /** @hide */
    public void setDiscoverableTimeout(int timeout) {
        try {
            mService.setDiscoverableTimeout(timeout);
        } catch (RemoteException e) {Log.e(TAG, "", e);}
    }

    /**
     * Start the remote device discovery process.
     * <p>The discovery process usually involves an inquiry scan of about 12
     * seconds, followed by a page scan of each new device to retrieve its
     * Bluetooth name.
     * <p>This is an asynchronous call, it will return immediately. Register
     * for {@link #ACTION_DISCOVERY_STARTED} and {@link
     * #ACTION_DISCOVERY_FINISHED} intents to determine exactly when the
     * discovery starts and completes. Register for {@link
     * BluetoothDevice#ACTION_FOUND} to be notified as remote Bluetooth devices
     * are found.
     * <p>Device discovery is a heavyweight procedure. New connections to
     * remote Bluetooth devices should not be attempted while discovery is in
     * progress, and existing connections will experience limited bandwidth
     * and high latency. Use {@link #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
     * {@link BluetoothAdapter#cancelDiscovery()} even if it
     * did not directly request a discovery, just to be sure.
     * <p>Device discovery will only find remote devices that are currently
     * <i>discoverable (inquiry scan enabled). Many Bluetooth devices are
     * not discoverable by default, and need to be entered into a special mode.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH_ADMIN}.
     *
     * @return true on success, false on error
     */
    public boolean startDiscovery() {
        try {
            return mService.startDiscovery();
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return false;
    }

    /**
     * Cancel the current device discovery process.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH_ADMIN}.
     * <p>Because discovery is a heavyweight precedure for the Bluetooth
     * adapter, this method should always be called before attempting to connect
     * to a remote device with {@link
     * android.bluetooth.BluetoothSocket#connect()}. Discovery is not managed by
     * the  Activity, but is run as a system service, so an application should
     * always call cancel discovery even if it did not directly request a
     * discovery, just to be sure.
     *
     * @return true on success, false on error
     */
    public boolean cancelDiscovery() {
        try {
            mService.cancelDiscovery();
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return false;
    }

    /**
     * Return true if the local Bluetooth adapter is currently in the device
     * discovery process.
     * <p>Device discovery is a heavyweight procedure. New connections to
     * remote Bluetooth devices should not be attempted while discovery is in
     * progress, and existing connections will experience limited bandwidth
     * and high latency. Use {@link #cancelDiscovery()} to cancel an ongoing
     * discovery.
     * <p>Applications can also register for {@link #ACTION_DISCOVERY_STARTED}
     * or {@link #ACTION_DISCOVERY_FINISHED} to be notified when discovery
     * starts or completes.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH}.
     *
     * @return true if discovering
     */
    public boolean isDiscovering() {
        try {
            return mService.isDiscovering();
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return false;
    }

    /**
     * Return the set of {@link BluetoothDevice} objects that are bonded
     * (paired) to the local adapter.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH}.
     *
     * @return unmodifiable set of {@link BluetoothDevice}, or null on error
     */
    public Set<BluetoothDevice> getBondedDevices() {
        try {
            return toDeviceSet(mService.listBonds());
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        return null;
    }

    /**
     * Picks RFCOMM channels until none are left.
     * Avoids reserved channels.
     */
    private static class RfcommChannelPicker {
        private static final int[] RESERVED_RFCOMM_CHANNELS =  new int[] {
            10,  // HFAG
            11,  // HSAG
            12,  // OPUSH
            19,  // PBAP
        };
        private static LinkedList<Integer> sChannels;  // master list of non-reserved channels
        private static Random sRandom;

        private final LinkedList<Integer> mChannels;  // local list of channels left to try

        private final UUID mUuid;

        public RfcommChannelPicker(UUID uuid) {
            synchronized (RfcommChannelPicker.class) {
                if (sChannels == null) {
                    // lazy initialization of non-reserved rfcomm channels
                    sChannels = new LinkedList<Integer>();
                    for (int i = 1; i <= BluetoothSocket.MAX_RFCOMM_CHANNEL; i++) {
                        sChannels.addLast(new Integer(i));
                    }
                    for (int reserved : RESERVED_RFCOMM_CHANNELS) {
                        sChannels.remove(new Integer(reserved));
                    }
                    sRandom = new Random();
                }
                mChannels = (LinkedList<Integer>)sChannels.clone();
            }
            mUuid = uuid;
        }
        /* Returns next random channel, or -1 if we're out */
        public int nextChannel() {
            if (mChannels.size() == 0) {
                return -1;
            }
            return mChannels.remove(sRandom.nextInt(mChannels.size()));
        }
    }

    /**
     * Create a listening, secure RFCOMM Bluetooth socket.
     * <p>A remote device connecting to this socket will be authenticated and
     * communication on this socket will be encrypted.
     * <p>Use {@link BluetoothServerSocket#accept} to retrieve incoming
     * connections from a listening {@link BluetoothServerSocket}.
     * <p>Valid RFCOMM channels are in range 1 to 30.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH_ADMIN}
     * @param channel RFCOMM channel to listen on
     * @return a listening RFCOMM BluetoothServerSocket
     * @throws IOException on error, for example Bluetooth not available, or
     *                     insufficient permissions, or channel in use.
     * @hide
     */
    public BluetoothServerSocket listenUsingRfcommOn(int channel) throws IOException {
        BluetoothServerSocket socket = new BluetoothServerSocket(
                BluetoothSocket.TYPE_RFCOMM, true, true, channel);
        int errno = socket.mSocket.bindListen();
        if (errno != 0) {
            try {
                socket.close();
            } catch (IOException e) {}
            socket.mSocket.throwErrnoNative(errno);
        }
        return socket;
    }

    /**
     * Create a listening, secure RFCOMM Bluetooth socket with Service Record.
     * <p>A remote device connecting to this socket will be authenticated and
     * communication on this socket will be encrypted.
     * <p>Use {@link BluetoothServerSocket#accept} to retrieve incoming
     * connections from a listening {@link BluetoothServerSocket}.
     * <p>The system will assign an unused RFCOMM channel to listen on.
     * <p>The system will also register a Service Discovery
     * Protocol (SDP) record with the local SDP server containing the specified
     * UUID, service name, and auto-assigned channel. Remote Bluetooth devices
     * can use the same UUID to query our SDP server and discover which channel
     * to connect to. This SDP record will be removed when this socket is
     * closed, or if this application closes unexpectedly.
     * <p>Use {@link BluetoothDevice#createRfcommSocketToServiceRecord} to
     * connect to this socket from another device using the same {@link UUID}.
     * <p>Requires {@link android.Manifest.permission#BLUETOOTH}
     * @param name service name for SDP record
     * @param uuid uuid for SDP record
     * @return a listening RFCOMM BluetoothServerSocket
     * @throws IOException on error, for example Bluetooth not available, or
     *                     insufficient permissions, or channel in use.
     */
    public BluetoothServerSocket listenUsingRfcommWithServiceRecord(String name, UUID uuid)
            throws IOException {
        RfcommChannelPicker picker = new RfcommChannelPicker(uuid);

        BluetoothServerSocket socket;
        int channel;
        int errno;
        while (true) {
            channel = picker.nextChannel();

            if (channel == -1) {
                throw new IOException("No available channels");
            }

            socket = new BluetoothServerSocket(
                    BluetoothSocket.TYPE_RFCOMM, true, true, channel);
            errno = socket.mSocket.bindListen();
            if (errno == 0) {
                if (DBG) Log.d(TAG, "listening on RFCOMM channel " + channel);
                break;  // success
            } else if (errno == BluetoothSocket.EADDRINUSE) {
                if (DBG) Log.d(TAG, "RFCOMM channel " + channel + " in use");
                try {
                    socket.close();
                } catch (IOException e) {}
                continue;  // try another channel
            } else {
                try {
                    socket.close();
                } catch (IOException e) {}
                socket.mSocket.throwErrnoNative(errno);  // Exception as a result of bindListen()
            }
        }

        int handle = -1;
        try {
            handle = mService.addRfcommServiceRecord(name, new ParcelUuid(uuid), channel,
                    new Binder());
        } catch (RemoteException e) {Log.e(TAG, "", e);}
        if (handle == -1) {
            try {
                socket.close();
            } catch (IOException e) {}
            throw new IOException("Not able to register SDP record for " + name);
        }
        socket.setCloseHandler(mHandler, handle);
        return socket;
    }

    /**
     * Construct an unencrypted, unauthenticated, RFCOMM server socket.
     * Call #accept to retrieve connections to this socket.
     * @return An RFCOMM BluetoothServerSocket
     * @throws IOException On error, for example Bluetooth not available, or
     *                     insufficient permissions.
     * @hide
     */
    public BluetoothServerSocket listenUsingInsecureRfcommOn(int port) throws IOException {
        BluetoothServerSocket socket = new BluetoothServerSocket(
                BluetoothSocket.TYPE_RFCOMM, false, false, port);
        int errno = socket.mSocket.bindListen();
        if (errno != 0) {
            try {
                socket.close();
            } catch (IOException e) {}
            socket.mSocket.throwErrnoNative(errno);
        }
        return socket;
    }

    /**
     * Construct a SCO server socket.
     * Call #accept to retrieve connections to this socket.
     * @return A SCO BluetoothServerSocket
     * @throws IOException On error, for example Bluetooth not available, or
     *                     insufficient permissions.
     * @hide
     */
    public static BluetoothServerSocket listenUsingScoOn() throws IOException {
        BluetoothServerSocket socket = new BluetoothServerSocket(
                BluetoothSocket.TYPE_SCO, false, false, -1);
        int errno = socket.mSocket.bindListen();
        if (errno != 0) {
            try {
                socket.close();
            } catch (IOException e) {}
            socket.mSocket.throwErrnoNative(errno);
        }
        return socket;
    }

    private Set<BluetoothDevice> toDeviceSet(String[] addresses) {
        Set<BluetoothDevice> devices = new HashSet(addresses.length);
        for (int i = 0; i < addresses.length; i++) {
            devices.add(getRemoteDevice(addresses[i]));
        }
        return Collections.unmodifiableSet(devices);
    }

    private Handler mHandler = new Handler() {
        public void handleMessage(Message msg) {
            /* handle socket closing */
            int handle = msg.what;
            try {
                if (DBG) Log.d(TAG, "Removing service record " + Integer.toHexString(handle));
                mService.removeServiceRecord(handle);
            } catch (RemoteException e) {Log.e(TAG, "", e);}
        }
    };

    /**
     * Validate a Bluetooth address, such as "00:43:A8:23:10:F0"
     * <p>Alphabetic characters must be uppercase to be valid.
     *
     * @param address Bluetooth address as string
     * @return true if the address is valid, false otherwise
     */
    public static boolean checkBluetoothAddress(String address) {
        if (address == null || address.length() != ADDRESS_LENGTH) {
            return false;
        }
        for (int i = 0; i < ADDRESS_LENGTH; i++) {
            char c = address.charAt(i);
            switch (i % 3) {
            case 0:
            case 1:
                if ((c >= '0' && c <= '9') || (c >= 'A' && c <= 'F')) {
                    // hex character, OK
                    break;
                }
                return false;
            case 2:
                if (c == ':') {
                    break;  // OK
                }
                return false;
            }
        }
        return true;
    }
}

Other Android examples (source code examples)

Here is a short list of links related to this Android BluetoothAdapter.java source code file:

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