实现需要的权限：由于安卓4.x版以上的版本使用蓝牙，需要开启定位权限才能搜索到附近的蓝牙设备

<uses-permission android:name="android.permission.BLUETOOTH"/> 
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/> 
 
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> 
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

服务端

实现思路：
1，拿到本地蓝牙设备
.2，蓝牙之间的通讯需要一个唯一识别UUID来匹配正确的设备，使用UUID获取蓝牙的通讯Socket.3 ，开启获取数据的线程

public class MainActivity extends AppCompatActivity implements View.OnClickListener { 
 
BluetoothSocket BTSocket; 
BluetoothAdapter BTAdapter; 
Button bt_start; 
TextView tv_msg; 
StringBuilder sb; 
 
@Override
protected void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.activity_main); 
bt_start = (Button) findViewById(R.id.bt_start); 
tv_msg = (TextView) findViewById(R.id.tv_msg); 
bt_start.setOnClickListener(this); 
sb = new StringBuilder(); 
//拿到本地蓝牙设备 
BTAdapter = BluetoothAdapter.getDefaultAdapter(); 
} 
 
/** 
* UI文本输出 
* 
* @param msg 
*/
public void show(String msg) { 
sb.append(msg + "\n"); 
runOnUiThread(new Runnable() { 
@Override
public void run() { 
tv_msg.setText(sb.toString()); 
} 
}); 
} 
 
@Override
public void onClick(View v) { 
//开启服务器 
ServerThread startServerThread = new ServerThread(); 
startServerThread.start(); 
} 
 
/** 
* 开启服务器 
*/
private class ServerThread extends Thread { 
public void run() { 
try { 
BluetoothServerSocket mserverSocket = BTAdapter.listenUsingRfcommWithServiceRecord("btspp", 
UUID.fromString("00001101-0000-1000-8000-00805F9B34FB")); 
show("服务端:等待连接"); 
 
BTSocket = mserverSocket.accept(); 
show("服务端:连接成功"); 
 
readThread mreadThread = new readThread(); 
mreadThread.start(); 
show("服务端:启动接受数据"); 
} catch (IOException e) { 
e.printStackTrace(); 
} 
} 
} 
 
/** 
* 读取数据 
*/
private class readThread extends Thread { 
public void run() { 
byte[] buffer = new byte[1024]; 
int bytes; 
InputStream mmInStream = null; 
try { 
mmInStream = BTSocket.getInputStream(); 
show("服务端:获得输入流"); 
} catch (IOException e1) { 
e1.printStackTrace(); 
} 
while (true) { 
try { 
if ((bytes = mmInStream.read(buffer)) > 0) { 
byte[] buf_data = new byte[bytes]; 
for (int i = 0; i < bytes; i++) { 
buf_data[i] = buffer[i]; 
} 
String s = new String(buf_data); 
show("服务端:读取数据了~~" + s); 
} 
} catch (IOException e) { 
try { 
mmInStream.close(); 
} catch (IOException e1) { 
e1.printStackTrace(); 
} 
break; 
} 
} 
} 
} 
 
}

客户端

实现思路：
1，检查是否开启蓝牙
2，注册一系列蓝牙的广播
。3，由于蓝牙每经过一个阶段都会发送一个广播，根据广播来实现对应的方法
4，蓝牙配对- >蓝牙连接- >发送消息（UUID必须相同）

public class MainActivity extends AppCompatActivity implements View.OnClickListener { 
 
private TextView tv_msg; 
private Button bt_search, bt_send; 
private BluetoothSocket BTSocket; 
private BluetoothAdapter BTAdapter; 
private BluetoothDevice device; 
private StringBuilder sb; 
 
@Override
protected void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.activity_main); 
 
bt_search = (Button) findViewById(R.id.bt_search); 
bt_send = (Button) findViewById(R.id.bt_send); 
tv_msg = (TextView) findViewById(R.id.tv_msg); 
bt_search.setOnClickListener(this); 
bt_send.setOnClickListener(this); 
sb = new StringBuilder(); 
 
show("客户端:检查BT"); 
checkBT(this); 
show("客户端:注册接收者"); 
registerBTReceiver(); 
} 
 
/** 
* UI文本输出 
* 
* @param msg 
*/
public void show(String msg) { 
sb.append(msg + "\n"); 
runOnUiThread(new Runnable() { 
@Override
public void run() { 
tv_msg.setText(sb.toString()); 
} 
}); 
} 
 
@Override
public void onClick(View v) { 
switch (v.getId()) { 
case R.id.bt_search: 
show("客户端:开始寻找设备"); 
BTAdapter.startDiscovery(); 
break; 
case R.id.bt_send: 
sendMessage(); 
break; 
} 
} 
 
/** 
* 检查蓝牙 
*/
public void checkBT(Context context) { 
BTAdapter = BluetoothAdapter.getDefaultAdapter(); 
if (BTAdapter != null) { 
if (!BTAdapter.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); 
} 
} else { 
System.out.println("本地设备驱动异常!"); 
} 
} 
 
/** 
* 开启客户端 
*/
private class clientThread extends Thread { 
public void run() { 
try { 
//创建一个Socket连接：只需要服务器在注册时的UUID号 
BTSocket = device.createRfcommSocketToServiceRecord(UUID.fromString("00001101-0000-1000-8000-00805F9B34FB")); 
//连接 
show("客户端:开始连接..."); 
BTSocket.connect(); 
show("客户端:连接成功"); 
//启动接受数据 
show("客户端:启动接受数据"); 
readThread mreadThread = new readThread(); 
mreadThread.start(); 
} catch (IOException e) { 
show("客户端:连接服务端异常！断开连接重新试一试"); 
e.printStackTrace(); 
} 
} 
} 
 
/** 
* 读取数据 
*/
private class readThread extends Thread { 
public void run() { 
byte[] buffer = new byte[1024]; 
int bytes; 
InputStream is = null; 
try { 
is = BTSocket.getInputStream(); 
show("客户端:获得输入流"); 
} catch (IOException e1) { 
e1.printStackTrace(); 
} 
while (true) { 
try { 
if ((bytes = is.read(buffer)) > 0) { 
byte[] buf_data = new byte[bytes]; 
for (int i = 0; i < bytes; i++) { 
buf_data[i] = buffer[i]; 
} 
String s = new String(buf_data); 
show("客户端:读取数据了" + s); 
} 
} catch (IOException e) { 
try { 
is.close(); 
} catch (IOException e1) { 
e1.printStackTrace(); 
} 
break; 
} 
} 
} 
} 
 
/** 
* 发送数据 
*/
public void sendMessage() { 
if (BTSocket == null) { 
Toast.makeText(this, "没有连接", Toast.LENGTH_SHORT).show(); 
return; 
} 
try { 
OutputStream os = BTSocket.getOutputStream(); 
os.write("我爱你dahsid132456@#%￥*".getBytes()); 
os.flush(); 
show("客户端:发送信息成功"); 
} catch (IOException e) { 
e.printStackTrace(); 
} 
} 
 
/** 
* 注册广播 
*/
public void registerBTReceiver() { 
// 设置广播信息过滤 
IntentFilter intentFilter = new IntentFilter(); 
intentFilter.addAction(BluetoothDevice.ACTION_FOUND); 
intentFilter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED); 
intentFilter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED); 
intentFilter.addAction(BluetoothAdapter.ACTION_STATE_CHANGED); 
intentFilter.addAction(BluetoothDevice.ACTION_BOND_STATE_CHANGED); 
// 注册广播接收器，接收并处理搜索结果 
registerReceiver(BTReceive, intentFilter); 
} 
 
/** 
* 注销广播 
*/
public void unregisterBTReceiver() { 
unregisterReceiver(BTReceive); 
} 
 
@Override
protected void onDestroy() { 
super.onDestroy(); 
unregisterBTReceiver(); 
} 
 
/** 
* 广播接收者 
*/
private BroadcastReceiver BTReceive = new BroadcastReceiver() { 
@Override
public void onReceive(Context context, Intent intent) { 
String action = intent.getAction(); 
if (BluetoothDevice.ACTION_FOUND.equals(action)) { 
device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE); 
show("客户端:找到的BT名:" + device.getName()); 
// 如果查找到的设备符合要连接的设备，处理 
if (device.getName().equalsIgnoreCase("xu")) { 
show("客户端:配对xu蓝牙:"); 
// 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 
BTAdapter.cancelDiscovery(); 
// 获取蓝牙设备的连接状态 
int connectState = device.getBondState(); 
switch (connectState) { 
// 未配对 
case BluetoothDevice.BOND_NONE: 
show("客户端:开始配对:"); 
try { 
Method createBondMethod = BluetoothDevice.class.getMethod("createBond"); 
createBondMethod.invoke(device); 
} catch (Exception e) { 
e.printStackTrace(); 
} 
break; 
// 已配对 
case BluetoothDevice.BOND_BONDED: 
try { 
show("客户端:开始连接:"); 
clientThread clientConnectThread = new clientThread(); 
clientConnectThread.start(); 
} catch (Exception e) { 
e.printStackTrace(); 
} 
break; 
} 
} 
} else if (BluetoothDevice.ACTION_BOND_STATE_CHANGED.equals(action)) { 
// 获取蓝牙设备的连接状态 
int connectState = device.getBondState(); 
// 已配对 
if (connectState == BluetoothDevice.BOND_BONDED) { 
try { 
show("客户端:开始连接:"); 
clientThread clientConnectThread = new clientThread(); 
clientConnectThread.start(); 
} catch (Exception e) { 
e.printStackTrace(); 
} 
} 
} 
show(action); 
} 
};

}

蓝牙广播内容：

ACTION_STATE_CHANGED当你蓝牙开启或者关闭的时候发送
ACTION_FOUND当你匹配到附近蓝牙设备时发送
ACTION_DISCOVERY_STARTED当你开始搜索附近蓝牙设备时发送
ACTION_DISCOVERY_FINISHED当你结束搜索附近蓝牙设备时发送
ACTION_BOND_STATE_CHANGED当你蓝牙设备匹配状态发生变化时发送