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2013年6月3日 星期一

Android Bluetooth API 使用心得筆記

1.Bluetooth基本概念
可以參考BlueCove這個實作JSR82的Project，裡面的這張圖對Bluetooth解說很清楚，可供參考。

Bluetooth Stack的部份在不同系統、程式語言上都是相同的，會有差異的只有頂層的Abstract API。

若想對Bluetooth整體軟硬体有仔細的了解可以參考「Bluetooth Application Programming with the Java APIs Essentials Edition」這本書。

2.Android Bluetooth開發基本需求
Android SDK 2.0以上(含2.0)版本。
支援Android 2.0的手機一隻(Android Emulater無法模擬Bluetooth，所以一定要有實體手機)。

3.實作參考文件
http://developer.android.com/guide/topics/wireless/bluetooth.html
http://www.anddev.org/serial_over_bluetooth_simple_test_client-t11106.html

一般來說，我們只會實作Bluetooth Client的程式去跟其它的Bluetooth硬體溝通取資料。連線方式大多是利用Serial Port Service方式去跟遠端的裝置溝通，所以相對應的UUID不能設錯，一定要設成下述範例這組UUID，不然會發生找不到Service的問題(附帶一提，這是假設一般遠端裝置有提供Serial Port Service，所以你才可以用這組UUID來進行通訊，如果遠端裝置比較特別就要去查硬體規格去看它提供的Service是哪些，找出對應的UUID)。
1
private static final UUID SERIAL_PORT_SERVICE_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");


4.Android Bluetooth API目前的限制
目前只支援RFCOMM的方式進行通訊

5.實作參考範例
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// 取自http://www.anddev.org/serial_over_bluetooth_simple_test_client-t11106.html裡的範例
package  com.example.thinbtclient;
 
import java.io.IOException;
import java.io.OutputStream;
import java.util.UUID;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;
 
public class ThinBTClient extends Activity {
     
     private static final String TAG = "THINBTCLIENT";
     private static final boolean D = true;
     private BluetoothAdapter mBluetoothAdapter = null;
     private BluetoothSocket btSocket = null;
     private OutputStream outStream = null;
     // Well known SPP UUID (will *probably* map to
     // RFCOMM channel 1 (default) if not in use);
     // see comments in onResume().
     private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
 
     // ==> hardcode your server's MAC address here <==
     private static String address = "XX:XX:XX:XX:XX:XX";
 
     /** Called when the activity is first created. */
     @Override
     public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.main);
 
          if (D)
               Log.e(TAG, "+++ ON CREATE +++");
 
          mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
          if (mBluetoothAdapter == null) {
               Toast.makeText(this,
                    "Bluetooth is not available.",
                    Toast.LENGTH_LONG).show();
               finish();
               return;
          }
 
          if (!mBluetoothAdapter.isEnabled()) {
               Toast.makeText(this,
                    "Please enable your BT and re-run this program.",
                    Toast.LENGTH_LONG).show();
               finish();
               return;
          }
 
          if (D)
               Log.e(TAG, "+++ DONE IN ON CREATE, GOT LOCAL BT ADAPTER +++");
     }
 
     @Override
     public void onStart() {
          super.onStart();
          if (D)
               Log.e(TAG, "++ ON START ++");
     }
 
     @Override
     public void onResume() {
          super.onResume();
 
          if (D) {
               Log.e(TAG, "+ ON RESUME +");
               Log.e(TAG, "+ ABOUT TO ATTEMPT CLIENT CONNECT +");
          }
 
          // When this returns, it will 'know' about the server,
          // via it's MAC address.
          BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
 
          // We need two things before we can successfully connect
          // (authentication issues aside): a MAC address, which we
          // already have, and an RFCOMM channel.
          // Because RFCOMM channels (aka ports) are limited in
          // number, Android doesn't allow you to use them directly;
          // instead you request a RFCOMM mapping based on a service
          // ID. In our case, we will use the well-known SPP Service
          // ID. This ID is in UUID (GUID to you Microsofties)
          // format. Given the UUID, Android will handle the
          // mapping for you. Generally, this will return RFCOMM 1,
          // but not always; it depends what other BlueTooth services
          // are in use on your Android device.
          try {
               btSocket = device.createRfcommSocketToServiceRecord(MY_UUID);
          } catch (IOException e) {
               Log.e(TAG, "ON RESUME: Socket creation failed.", e);
          }
 
          // Discovery may be going on, e.g., if you're running a
          // 'scan for devices' search from your handset's Bluetooth
          // settings, so we call cancelDiscovery(). It doesn't hurt
          // to call it, but it might hurt not to... discovery is a
          // heavyweight process; you don't want it in progress when
          // a connection attempt is made.
          mBluetoothAdapter.cancelDiscovery();
 
          // Blocking connect, for a simple client nothing else can
          // happen until a successful connection is made, so we
          // don't care if it blocks.
          try {
               btSocket.connect();
               Log.e(TAG, "ON RESUME: BT connection established, data transfer link open.");
          } catch (IOException e) {
               try {
                    btSocket.close();
               } catch (IOException e2) {
                    Log.e(TAG,"ON RESUME: Unable to close socket during connection failure", e2);
               }
          }
 
          // Create a data stream so we can talk to server.
          if (D)
               Log.e(TAG, "+ ABOUT TO SAY SOMETHING TO SERVER +");
 
          try {
               outStream = btSocket.getOutputStream();
          } catch (IOException e) {
               Log.e(TAG, "ON RESUME: Output stream creation failed.", e);
          }
 
          String message = "Hello message from client to server.";
          byte[] msgBuffer = message.getBytes();
          try {
               outStream.write(msgBuffer);
          } catch (IOException e) {
               Log.e(TAG, "ON RESUME: Exception during write.", e);
          }
     }
 
     @Override
     public void onPause() {
          super.onPause();
 
          if (D)
               Log.e(TAG, "- ON PAUSE -");
 
          if (outStream != null) {
               try {
                    outStream.flush();
               } catch (IOException e) {
                    Log.e(TAG, "ON PAUSE: Couldn't flush output stream.", e);
               }
          }
 
          try  {
               btSocket.close();
          } catch (IOException e2) {
               Log.e(TAG, "ON PAUSE: Unable to close socket.", e2);
          }
     }
 
     @Override
     public void onStop() {
          super.onStop();
          if (D)
               Log.e(TAG, "-- ON STOP --");
     }
 
     @Override
     public void onDestroy() {
          super.onDestroy();
          if (D)
               Log.e(TAG, "--- ON DESTROY ---");
     }
}
 
AndroidManifest.xml裡的Permission設定加下述二行
"android.permission.BLUETOOTH_ADMIN"
/> "android.permission.BLUETOOTH" />

Android SDK 2.1裡的Bluetooh Sample (在 x:/android sdk安裝目錄/platforms/android-2.1/samples/BluetoothChat 裡面，或是到 http://developer.android.com/resources/samples/BluetoothChat/index.html 看範例，二者是一樣的東西)

http://code.google.com/p/apps-for-android/ 裡面有個 BTClickLinkCompete Sample，可經由SVN去下載回來看 

資料來源
張貼者： hivenson 於 上午9:16
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