上篇文章中，我們主要介紹了藍牙模塊，傳統/經典藍牙模塊BT和低功耗藍牙BLE及其相關的API，不熟悉的可以查看Android藍牙開發（一）藍牙模塊及核心API 進行了解。
本篇主要記錄用到的經典藍牙開發流程及連接通訊。
1. 開啟藍牙
藍牙連接前，給與相關系統權限：
<!-- 使用藍牙的權限 -->
<uses-permission android:name="android.permission.BLUETOOTH" />
<!-- 掃描藍牙設備或者操作藍牙設置 -->
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<!--模糊定位權限，僅作用於6.0+-->
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<!--精准定位權限，僅作用於6.0+-->
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
安卓6.0以上系統要動態請求及獲取開啟GPS內容：
/**
* 檢查GPS是否打開
*/
private boolean checkGPSIsOpen() {
LocationManager locationManager = (LocationManager) mContext.getSystemService(Context.LOCATION_SERVICE);
if (locationManager == null)
return false;
return locationManager.isProviderEnabled(android.location.LocationManager.GPS_PROVIDER);
}
藍牙核心對象獲取，若獲取對象為null則說明設備不支持藍牙：
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
判斷藍牙是否開啟，沒有則開啟：
//判斷藍牙是否開啟
if (!mBluetoothAdapter.isEnabled()) {
//開啟藍牙，耗時，監聽廣播進行后續操作
mBluetoothAdapter.enable();
}
2.掃描藍牙
藍牙掃描：
mBluetoothAdapter.startDiscovery();
取消掃描：
mBluetoothAdapter.cancelDiscovery();
3.藍牙狀態監聽
藍牙監聽廣播，監聽藍牙開關，發現設備，掃描結束等狀態，定義狀態回調接口，進行對應操作，例如：監聽到藍牙開啟后，進行設備掃描；發現設備后進行連接等。
/**
* 監聽藍牙廣播-各種狀態
*/
public class BluetoothReceiver extends BroadcastReceiver {
private static final String TAG = BluetoothReceiver.class.getSimpleName();
private final OnBluetoothReceiverListener mOnBluetoothReceiverListener;
public BluetoothReceiver(Context context,OnBluetoothReceiverListener onBluetoothReceiverListener) {
mOnBluetoothReceiverListener = onBluetoothReceiverListener;
context.registerReceiver(this,getBluetoothIntentFilter());
}
private IntentFilter getBluetoothIntentFilter() {
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothAdapter.ACTION_STATE_CHANGED);//藍牙開關狀態
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);//藍牙開始搜索
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);//藍牙搜索結束
filter.addAction(BluetoothDevice.ACTION_FOUND);//藍牙發現新設備(未配對的設備)
return filter;
}
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (action == null) {
return;
}
Log.i(TAG, "===" + action);
BluetoothDevice dev = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
if (dev != null) {
Log.i(TAG, "BluetoothDevice: " + dev.getName() + ", " + dev.getAddress());
}
switch (action) {
case BluetoothAdapter.ACTION_STATE_CHANGED:
int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, 0);
Log.i(TAG, "STATE: " + state);
if (mOnBluetoothReceiverListener != null) {
mOnBluetoothReceiverListener.onStateChanged(state);
}
break;
case BluetoothAdapter.ACTION_DISCOVERY_STARTED:
Log.i(TAG, "ACTION_DISCOVERY_STARTED ");
break;
case BluetoothAdapter.ACTION_DISCOVERY_FINISHED:
if (mOnBluetoothReceiverListener != null) {
mOnBluetoothReceiverListener.onScanFinish();
}
break;
case BluetoothDevice.ACTION_FOUND:
short rssi = intent.getShortExtra(BluetoothDevice.EXTRA_RSSI, Short.MAX_VALUE);
Log.i(TAG, "EXTRA_RSSI:" + rssi);
if (mOnBluetoothReceiverListener != null) {
mOnBluetoothReceiverListener.onDeviceFound(dev);
}
break;
default:
break;
}
}
public interface OnBluetoothReceiverListener {
/**
* 發現設備
*
* @param bluetoothDevice 藍牙設備
*/
void onDeviceFound(BluetoothDevice bluetoothDevice);
/**
* 掃描結束
*/
void onScanFinish();
/**
* 藍牙開啟關閉狀態
*
* @param state 狀態
*/
void onStateChanged(int state);
}
}
4.通訊連接
客戶端，與服務端建立長連接，進行通訊：
/**
* 客戶端，與服務端建立長連接
*/
public class BluetoothClient extends BaseBluetooth {
public BluetoothClient(BTListener BTListener) {
super(BTListener);
}
/**
* 與遠端設備建立長連接
*
* @param bluetoothDevice 遠端設備
*/
public void connect(BluetoothDevice bluetoothDevice) {
close();
try {
// final BluetoothSocket socket = bluetoothDevice.createRfcommSocketToServiceRecord(SPP_UUID); //加密傳輸，Android強制執行配對，彈窗顯示配對碼
final BluetoothSocket socket = bluetoothDevice.createInsecureRfcommSocketToServiceRecord(SPP_UUID); //明文傳輸(不安全)，無需配對
// 開啟子線程（必須在新線程中進行連接操作）
EXECUTOR.execute(new Runnable() {
@Override
public void run() {
//連接，並進行循環讀取
loopRead(socket);
}
});
} catch (Throwable e) {
close();
}
}
}
服務端監聽客戶端發起的連接，進行接收及通訊：
/**
* 服務端監聽和連接線程，只連接一個設備
*/
public class BluetoothServer extends BaseBluetooth {
private BluetoothServerSocket mSSocket;
public BluetoothServer(BTListener BTListener) {
super(BTListener);
listen();
}
/**
* 監聽客戶端發起的連接
*/
public void listen() {
try {
BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();
// mSSocket = adapter.listenUsingRfcommWithServiceRecord("BT", SPP_UUID); //加密傳輸，Android強制執行配對，彈窗顯示配對碼
mSSocket = adapter.listenUsingInsecureRfcommWithServiceRecord("BT", SPP_UUID); //明文傳輸(不安全)，無需配對
// 開啟子線程
EXECUTOR.execute(new Runnable() {
@Override
public void run() {
try {
BluetoothSocket socket = mSSocket.accept(); // 監聽連接
mSSocket.close(); // 關閉監聽，只連接一個設備
loopRead(socket); // 循環讀取
} catch (Throwable e) {
close();
}
}
});
} catch (Throwable e) {
close();
}
}
@Override
public void close() {
super.close();
try {
mSSocket.close();
} catch (Throwable e) {
e.printStackTrace();
}
}
}
客戶端連接及服務端監聽基類，用於客戶端和服務端之前Socket消息通訊，進行消息或文件的發送、接收，進行通訊關閉操作等：
public class BaseBluetooth {
public static final Executor EXECUTOR = Executors.newSingleThreadExecutor();
protected static final UUID SPP_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); //自定義
private static final String FILE_PATH = Environment.getExternalStorageDirectory().getAbsolutePath() + "/bluetooth/";
private static final int FLAG_MSG = 0; //消息標記
private static final int FLAG_FILE = 1; //文件標記
private BluetoothSocket mSocket;
private DataOutputStream mOut;
private BTListener mBTListener;
private boolean isRead;
private boolean isSending;
public BaseBluetooth(BTListener BTListener) {
mBTListener = BTListener;
}
/**
* 循環讀取對方數據(若沒有數據，則阻塞等待)
*/
public void loopRead(BluetoothSocket socket) {
mSocket = socket;
try {
if (!mSocket.isConnected())
mSocket.connect();
notifyUI(BTListener.CONNECTED, mSocket.getRemoteDevice());
mOut = new DataOutputStream(mSocket.getOutputStream());
DataInputStream in = new DataInputStream(mSocket.getInputStream());
isRead = true;
while (isRead) { //循環讀取
switch (in.readInt()) {
case FLAG_MSG: //讀取短消息
String msg = in.readUTF();
notifyUI(BTListener.MSG_RECEIVED, msg);
break;
case FLAG_FILE: //讀取文件
File file = new File(FILE_PATH);
if (!file.exists()) {
file.mkdirs();
}
String fileName = in.readUTF(); //文件名
long fileLen = in.readLong(); //文件長度
notifyUI(BTListener.MSG_RECEIVED, "正在接收文件(" + fileName + ")····················");
// 讀取文件內容
long len = 0;
int r;
byte[] b = new byte[4 * 1024];
FileOutputStream out = new FileOutputStream(FILE_PATH + fileName);
while ((r = in.read(b)) != -1) {
out.write(b, 0, r);
len += r;
if (len >= fileLen)
break;
}
notifyUI(BTListener.MSG_RECEIVED, "文件接收完成(存放在:" + FILE_PATH + ")");
break;
}
}
} catch (Throwable e) {
close();
}
}
/**
* 發送短消息
*/
public void sendMsg(String msg) {
if (isSending || TextUtils.isEmpty(msg))
return;
isSending = true;
try {
mOut.writeInt(FLAG_MSG); //消息標記
mOut.writeUTF(msg);
} catch (Throwable e) {
close();
}
notifyUI(BTListener.MSG_SEND, "發送短消息：" + msg);
isSending = false;
}
/**
* 發送文件
*/
public void sendFile(final String filePath) {
if (isSending || TextUtils.isEmpty(filePath))
return;
isSending = true;
EXECUTOR.execute(new Runnable() {
@Override
public void run() {
try {
notifyUI(BTListener.MSG_SEND, "正在發送文件(" + filePath + ")····················");
FileInputStream in = new FileInputStream(filePath);
File file = new File(filePath);
mOut.writeInt(FLAG_FILE); //文件標記
mOut.writeUTF(file.getName()); //文件名
mOut.writeLong(file.length()); //文件長度
int r;
byte[] b = new byte[4 * 1024];
while ((r = in.read(b)) != -1) {
mOut.write(b, 0, r);
}
notifyUI(BTListener.MSG_SEND, "文件發送完成.");
} catch (Throwable e) {
close();
}
isSending = false;
}
});
}
/**
* 關閉Socket連接
*/
public void close() {
try {
isRead = false;
if (mSocket != null) {
mSocket.close();
notifyUI(BTListener.DISCONNECTED, null);
}
} catch (Throwable e) {
e.printStackTrace();
}
}
/**
* 當前設備與指定設備是否連接
*/
public boolean isConnected(BluetoothDevice dev) {
boolean connected = (mSocket != null && mSocket.isConnected());
if (dev == null)
return connected;
return connected && mSocket.getRemoteDevice().equals(dev);
}
private void notifyUI(final int state, final Object obj) {
mBTListener.socketNotify(state, obj);
}
public interface BTListener {
int DISCONNECTED = 0;
int CONNECTED = 1;
int MSG_SEND = 2;
int MSG_RECEIVED = 3;
void socketNotify(int state, Object obj);
}
我這里只是簡單記錄了項目中用到的藍牙通訊，兩個設備之間不通過配對進行連接、通訊。
相關詳細內容及使用請查看Github項目：https://github.com/MickJson/BluetoothCS
藍牙配對操作及其它內容，可以詳細查看我下面的參考資料，寫的十分詳細，比如設備通過MAC地址，可以通過BluetoothAdapter獲取設備，再通過客戶端connect方法去進行連接等。
BluetoothDevice btDev = mBluetoothAdapter.getRemoteDevice(address);
最后
連接中遇到問題：read failed, socket might closed or timeout, read ret: -1。
通過改UUID，反射等方法都還是會出現錯誤。連接時，要確保服務端及客戶端都處於完全斷開狀態，否則連接就會出現以上問題，但偶爾還是會有問題，期待有什么好的方法可留言告訴我。
參考資料：
Android-經典藍牙(BT)-建立長連接傳輸短消息和文件
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