Android 蓝牙设备的查找和连接

1.权限

使用蓝牙设备需要先在Manifest中开放权限，位置如下。

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<manifest ...>

<application ...>

...
</application>

// 使用蓝牙设备的权限
<uses-permission
android:name="android.permission.BLUETOOTH"
/>
// 管理蓝牙设备的权限
<uses-permission
android:name="android.permission.BLUETOOTH_ADMIN"
/>
</manifest>

<manifest ...>
<application ...>
...
</application>

// 使用蓝牙设备的权限
<uses-permission android:name="android.permission.BLUETOOTH" />
// 管理蓝牙设备的权限
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
</manifest>

2.打开蓝牙

获得蓝牙适配器（android.bluetooth.BluetoothAdapter），检查该设备是否支持蓝牙，如果支持，就打开蓝牙。

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// 检查设备是否支持蓝牙
adapter = BluetoothAdapter.getDefaultAdapter();
if (adapter == null)

{
// 设备不支持蓝牙
}
// 打开蓝牙
if (!adapter.isEnabled())
{
Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);

// 设置蓝牙可见性，最多300秒

intent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION,
300);
context.startActivity(intent);
}

// 检查设备是否支持蓝牙
adapter = BluetoothAdapter.getDefaultAdapter();
if (adapter == null)
{
// 设备不支持蓝牙
}
// 打开蓝牙
if (!adapter.isEnabled())
{
Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
// 设置蓝牙可见性，最多300秒
intent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
context.startActivity(intent);
}

3.获取已配对的蓝牙设备（android.bluetooth.BluetoothDevice）

首次连接某蓝牙设备需要先配对，一旦配对成功，该设备的信息会被保存，以后连接时无需再配对，所以已配对的设备不一定是能连接的。

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BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();

Set<BluetoothDevice> devices = adapter.getBondedDevices();
for(int i=0; i<devices.size(); i++)

{
BluetoothDevice device = (BluetoothDevice) devices.iterator().next();

System.out.println(device.getName());
}

BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();
Set<BluetoothDevice> devices = adapter.getBondedDevices();
for(int i=0; i<devices.size(); i++)
{
BluetoothDevice device = (BluetoothDevice) devices.iterator().next();
System.out.println(device.getName());
}

4.搜索周围的蓝牙设备

适配器搜索蓝牙设备后将结果以广播形式传出去，所以需要自定义一个继承广播的类，在onReceive方法中获得并处理蓝牙设备的搜索结果。

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// 设置广播信息过滤
IntentFilter intentFilter = new IntentFilter();

intentFilter.addAction(BluetoothDevice.ACTION_FOUND);

intentFilter.addAction(BluetoothDevice.ACTION_BOND_STATE_CHANGED);

intentFilter.addAction(BluetoothAdapter.ACTION_SCAN_MODE_CHANGED);

intentFilter.addAction(BluetoothAdapter.ACTION_STATE_CHANGED);

// 注册广播接收器，接收并处理搜索结果

context.registerReceiver(receiver, intentFilter);
// 寻找蓝牙设备，android会将查找到的设备以广播形式发出去

adapter.startDiscovery();

// 设置广播信息过滤
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(BluetoothDevice.ACTION_FOUND);
intentFilter.addAction(BluetoothDevice.ACTION_BOND_STATE_CHANGED);
intentFilter.addAction(BluetoothAdapter.ACTION_SCAN_MODE_CHANGED);
intentFilter.addAction(BluetoothAdapter.ACTION_STATE_CHANGED);
// 注册广播接收器，接收并处理搜索结果
context.registerReceiver(receiver, intentFilter);
// 寻找蓝牙设备，android会将查找到的设备以广播形式发出去
adapter.startDiscovery();

自定义广播类

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private BroadcastReceiver receiver =
new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {

String action = intent.getAction();
if (BluetoothDevice.ACTION_FOUND.equals(action)) {

BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);

System.out.println(device.getName());
}
}
}

private BroadcastReceiver receiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
System.out.println(device.getName());
}
}
}

5.蓝牙设备的配对和状态监视

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private BroadcastReceiver receiver =
new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {

String action = intent.getAction();
if (BluetoothDevice.ACTION_FOUND.equals(action)) {

// 获取查找到的蓝牙设备
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);

System.out.println(device.getName());
// 如果查找到的设备符合要连接的设备，处理

if (device.getName().equalsIgnoreCase(name)) {

// 搜索蓝牙设备的过程占用资源比较多，一旦找到需要连接的设备后需要及时关闭搜索

adapter.cancelDiscovery();
// 获取蓝牙设备的连接状态

connectState = device.getBondState();
switch (connectState) {

// 未配对
case BluetoothDevice.BOND_NONE:

// 配对

try {

Method createBondMethod = BluetoothDevice.class.getMethod("createBond");

createBondMethod.invoke(device);

} catch (Exception e) {

e.printStackTrace();
}
break;

// 已配对
case BluetoothDevice.BOND_BONDED:

try {

// 连接

connect(device);
} catch (IOException e) {

e.printStackTrace();
}
break;

}
}
} else if(BluetoothDevice.ACTION_BOND_STATE_CHANGED.equals(action)) {

// 状态改变的广播
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);

if (device.getName().equalsIgnoreCase(name)) {

connectState = device.getBondState();

switch (connectState) {

case BluetoothDevice.BOND_NONE:

break;

case BluetoothDevice.BOND_BONDING:

break;

case BluetoothDevice.BOND_BONDED:

try {

// 连接

connect(device);
} catch (IOException e) {

e.printStackTrace();
}
break;

}
}
}
}
}

private BroadcastReceiver receiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// 获取查找到的蓝牙设备
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
System.out.println(device.getName());
// 如果查找到的设备符合要连接的设备，处理
if (device.getName().equalsIgnoreCase(name)) {
// 搜索蓝牙设备的过程占用资源比较多，一旦找到需要连接的设备后需要及时关闭搜索
adapter.cancelDiscovery();
// 获取蓝牙设备的连接状态
connectState = device.getBondState();
switch (connectState) {
// 未配对
case BluetoothDevice.BOND_NONE:
// 配对
try {
Method createBondMethod = BluetoothDevice.class.getMethod("createBond");
createBondMethod.invoke(device);
} catch (Exception e) {
e.printStackTrace();
}
break;
// 已配对
case BluetoothDevice.BOND_BONDED:
try {
// 连接
connect(device);
} catch (IOException e) {
e.printStackTrace();
}
break;
}
}
} else if(BluetoothDevice.ACTION_BOND_STATE_CHANGED.equals(action)) {
// 状态改变的广播
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
if (device.getName().equalsIgnoreCase(name)) {
connectState = device.getBondState();
switch (connectState) {
case BluetoothDevice.BOND_NONE:
break;
case BluetoothDevice.BOND_BONDING:
break;
case BluetoothDevice.BOND_BONDED:
try {
// 连接
connect(device);
} catch (IOException e) {
e.printStackTrace();
}
break;
}
}
}
}
}

6.蓝牙设备的连接

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private void connect(BluetoothDevice device)
throws IOException {
// 固定的UUID
final String SPP_UUID =
"00001101-0000-1000-8000-00805F9B34FB";

UUID uuid = UUID.fromString(SPP_UUID);
BluetoothSocket socket = device.createRfcommSocketToServiceRecord(uuid);

socket.connect();
}