Android蓝牙串口通讯【转】
本文轉載自:http://blog.sina.com.cn/s/blog_631e3f2601012ixi.html
Android藍牙串口通訊
閑著無聊玩起了Android藍牙模塊與單片機藍牙模塊的通信,簡單思路就是要手機通過藍牙發送控制指令給單片機,并作簡單的控制應用。單片機的藍牙模塊連接與程序暫且略過,此文主要描述Android手機藍牙客戶端遇到的那點破事。進入正題:
連接藍牙設備——藍牙客戶端:
Android手機一般以客戶端的角色主動連接SPP協議設備(接上藍牙模塊的數字傳感器),客戶端連接流程是:
1.使用registerReceiver注冊BroadcastReceiver來獲取藍牙狀態、搜索設備等消息;
????private?BroadcastReceiver?searchDevices?=?new?BroadcastReceiver() {?
???????public?void?onReceive(Context context, Intent intent) {
???????????String action = intent.getAction();
???????????Bundle b = intent.getExtras();
???????????Object[] lstName = b.keySet().toArray();?
???????????//?顯示所有收到的消息及其細節
???????????for?(int?i = 0; i < lstName.length; i++) {
??????????????String keyName = lstName[i].toString();
??????????????Log.e(keyName, String.valueOf(b.get(keyName)));
???????????}
???????????//搜索設備時,取得設備的MAC地址
???????????if?(BluetoothDevice.ACTION_FOUND.equals(action)) {
??????????????BluetoothDevice device = intent
?????????????????????.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
??????????????String str= device.getName() +?"|"?+ device.getAddress();
?????????????
??????????????if?(lstDevices.indexOf(str) == -1)//?防止重復添加
??????????????????lstDevices.add(str);?//?獲取設備名稱和mac地址
??????????????adtDevices.notifyDataSetChanged();
???????????}
???????}
????};
?
2.使用BlueAdatper的搜索:
????btAdapt.startDiscovery();
????3.在BroadcastReceiver的onReceive()里取得搜索所得的藍牙設備信息(如名稱,MAC,RSSI);
????4.通過設備的MAC地址來建立一個BluetoothDevice對象;
5.由BluetoothDevice衍生出BluetoothSocket,準備SOCKET來讀寫設備;
6.通過BluetoothSocket的createRfcommSocketToServiceRecord()方法來選擇連接的協議/服務,這里用的 ??????是SPP(UUID:00001101-0000-1000-8000-00805F9B34FB);
try?{?????
???????btSocket?= btDev.createRfcommSocketToServiceRecord(uuid);
????}?catch?(IOException e) {
????//?TODO?Auto-generated catch block
???????Log.e(TAG,?"Low: Connection failed.", e);?????
????}
成功后進行連接:
try?{
????btSocket.connect();????????????
????Log.e(TAG,?" BT connection established, data transfer link open.");
????mangeConnectedSocket(btSocket);//自定義函數進行藍牙通信處理
?
}?catch?(IOException e) {
????Log.e(TAG,?" Connection failed.", e);?
????setTitle("連接失敗..");
}??
7.Connect之后(如果還沒配對則系統自動提示),使用
??BluetoothSocket的getInputStream()和getOutputStream()來讀寫藍牙設備。
?讀寫可以歸到一個獨立線程去實現~ 注意:讀時必須一直循環讀取串口緩沖區,寫可以不需要。?
按以上7步逐次走過后,你就會發現Android藍牙模塊是多么的坑爹了。
出現問題:
????????在第6步一般初學者都會報錯:?執行.connect()發生異常Connection refused
????此時執行不下去咯,怎么辦怎么辦呢?
????于是邊debug邊網上找攻略,總算在Google出老外的一些做法,嘗試了下,貌似還可行。也即把
????btSocket的建立方法采用另一種方法替代,這里都使用端口1
Method m;
try?{
????m = btDev.getClass().getMethod("createRfcommSocket",?new?Class[] {int.class});
????btSocket?= (BluetoothSocket) m.invoke(btDev,?Integer.valueOf(1));
??????????????}?catch?(SecurityException e1) {
??????????????????//?TODO?Auto-generated catch block
??????????????????e1.printStackTrace();
??????????????}?catch?(NoSuchMethodException e1) {
??????????????????//?TODO?Auto-generated catch block
??????????????????e1.printStackTrace();
??????????????}?catch?(IllegalArgumentException?e) {
??????????????????//?TODO?Auto-generated catch block
??????????????????e.printStackTrace();
??????????????}?catch?(IllegalAccessException e) {
??????????????????//?TODO?Auto-generated catch block
??????????????????e.printStackTrace();
??????????????}?catch?(InvocationTargetException e) {
??????????????????//?TODO?Auto-generated catch block
??????????????????e.printStackTrace();
???????????}?
至此,這個問題貌似倒也解決了,程序繼續往下跑。
但這里請記住之前的異常,先別急著拋開~人家不一定一直都是異常哦
?
接下來的任務是,讓手機通過藍牙跟單片機的藍牙模塊通信,并發送數據,通過電腦串口調試助手顯示出來。具體實現,在mangeConnectedSocket(btSocket)方法中實現,里面通過啟動另一個Activity實現。不是重點,略過。
?
直到這里,我們都只是把手機藍牙模塊充當客戶端來使用,那什么時候會用到服務端呢?其實,之前手機藍牙與單片機藍牙模塊的通信,單片機藍牙模塊就充當了服務端(處于監聽狀態,被手機藍牙連接)。為了更好地搞清楚Android藍牙通信,我們接下來使用2個手機的藍牙進行通信。簡單地說,就是做一個“手機藍牙扣扣”,⊙﹏⊙b汗
?
一開始就想天真地把之前的程序同時燒到2部手機中,發現只有一部手機能正常建立socket連接(主動連接的那臺),而另一部卻遲遲沒有響應。原因很簡單,服務端的程序還沒有編寫!?
于是,開始服務端程序:開辟一個新的線程實現
連接藍牙設備——藍牙服務端:
????class?AcceptThread?extends?Thread {
????private?final?BluetoothServerSocket?serverSocket;
????public?AcceptThread() {
????????// Use a temporary object that is later assigned to mmServerSocket,
????????// because mmServerSocket is final?
????BluetoothServerSocket tmp=null;
????try?{
//tmp?= btAdapt.listenUsingRfcommWithServiceRecord("MyBluetoothApp",?uuid);
????Log.e(TAG,?"++BluetoothServerSocket established!++");
??Method listenMethod = ???????btAdapt.getClass().getMethod("listenUsingRfcommOn",
???new ??Class[]{int.class});
????tmp = ( BluetoothServerSocket) listenMethod.invoke(btAdapt, ?????????????????????????????????????????????????Integer.valueOf( 1));
??????????
???????}?catch?(SecurityException e) {
???????????//?TODO?Auto-generated catch block
???????????e.printStackTrace();
???????}?catch?(IllegalArgumentException?e) {
???????????//?TODO?Auto-generated catch block
???????????e.printStackTrace();
???????}?catch?(NoSuchMethodException e) {
???????????//?TODO?Auto-generated catch block
???????????e.printStackTrace();
???????}?catch?(IllegalAccessException e) {
???????????//?TODO?Auto-generated catch block
???????????e.printStackTrace();
???????}?catch?(InvocationTargetException e) {
???????????//?TODO?Auto-generated catch block
???????????e.printStackTrace();
???????}
??????
???????serverSocket=tmp;
????}???
???
???public?void?run() {
???????
????????// Keep listening until exception occurs or a socket is returned
?????????//mState!=STATE_CONNECTED
???while(true) {//這里是一直循環監聽,也可以設置mState來判斷
????????try?{
???????????socket?=?serverSocket.accept();
???????????Log.e(TAG,?"++BluetoothSocket established! DataLink open.++");
????????????}?catch?(IOException e) {
????????????????break;
????????????}
????????????// If a connection was accepted
????????????if?(socket?!=?null) {
????????????????// Do work to manage the connection (in a separate thread)
????????????????manageConnectedSocket();????
????????????????try?{
??????????????????serverSocket.close();
??????????????}?catch?(IOException e) {
??????????????????//?TODO?Auto-generated catch block
??????????????????e.printStackTrace();
??????????????}
????????????????break;
????????????}
????????}???????
}
?
????public?void?cancel() {
????????try?{
????????????serverSocket.close();
????????}?catch?(IOException e) { }
????}
}
?
安裝測試:當2部手機都裝上并打開同樣的程序后,通過藍牙檢索并連接,經測試可以成功連接上,雙雙進入“聊天界面”,嘿嘿
?
注意,這時候重新拾回之前那個異常,把socket連接建立的方法重新改為
btSocket?= btDev.createRfcommSocketToServiceRecord(uuid);//客戶端
對應的服務端程序:
tmp?= btAdapt.listenUsingRfcommWithServiceRecord("MyBluetoothApp",?uuid);//服務端
?
這樣繼續重新運行安裝測試,在2部手機上運行發現之前那個bug消失了~2部手機又雙雙進入聊天界面。
神奇~?
存在bug:
任一一部手機都只能成功啟動一次作為客戶端的主動連接,當退出聊天界面回到主界面時(服務端的AcceptThread還在繼續運行著),可再次主動連接另一部手機時就又報異常Connection refused。也就是說?客戶端的藍牙套接字2次連接時出錯~哎(注意我的客戶端藍牙連接程序是沒有放到一個獨立線程,而是放到一個按鈕監聽事件中)?
又折騰了好久,沒發現個所以然來,看來連完一次退出再連時就只好重啟程序咯。有哪位大神知道為什么的麻煩告知下哈!
若需要代碼,code下載
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