Android(安卓)Bluetooth 蓝牙基本操作

蓝牙是一种支持设备短距离传输数据的无线技术。android在2.0以后提供了这方面的支持。
从查找蓝牙设备到能够相互通信要经过几个基本步骤(本机做为服务器)：
1.设置权限
在manifest中配置

2.启动蓝牙
首先要查看本机是否支持蓝牙，获取BluetoothAdapter蓝牙适配器对象

BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();  if(mBluetoothAdapter == null){          //表明此手机不支持蓝牙  sijienet.com        return;  }  if(!mBluetoothAdapter.isEnabled()){ //蓝牙未开启，则开启蓝牙              Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);              startActivityForResult(enableIntent, REQUEST_ENABLE_BT);  }  //......  public void onActivityResult(int requestCode, int resultCode, Intent data){         if(requestCode == REQUEST_ENABLE_BT){                if(requestCode == RESULT_OK){                     //蓝牙已经开启                 }         }  }

3。发现蓝牙设备
这里可以细分为几个方面
(1)使本机蓝牙处于可见(即处于易被搜索到状态)，便于其他设备发现本机蓝牙

//使本机蓝牙在300秒内可被搜索  private void ensureDiscoverable() {          if (mBluetoothAdapter.getScanMode() !=              BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE) {              Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);              discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);              startActivity(discoverableIntent);          }  }

(2)查找已经配对的蓝牙设备，即以前已经配对过的设备

Set pairedDevices = mBluetoothAdapter.getBondedDevices();  if (pairedDevices.size() > 0) {      findViewById(R.id.title_paired_devices).setVisibility(View.VISIBLE);      for (BluetoothDevice device : pairedDevices) {          //device.getName() +" "+ device.getAddress());      }  } else {      mPairedDevicesArrayAdapter.add("没有找到已匹对的设备");  }

(3)通过mBluetoothAdapter.startDiscovery();搜索设备，要获得此搜索的结果需要注册
一个BroadcastReceiver来获取。先注册再获取信息，然后处理

//注册，当一个设备被发现时调用onReceive  IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);          this.registerReceiver(mReceiver, filter);    //当搜索结束后调用onReceive  filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);          this.registerReceiver(mReceiver, filter);  //.......  private BroadcastReceiver mReceiver = 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);                    // 已经配对的则跳过                   if (device.getBondState() != BluetoothDevice.BOND_BONDED) {                        mNewDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress());  //保存设备地址与名字                   }              }else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {  //搜索结束                  if (mNewDevicesArrayAdapter.getCount() == 0) {                      mNewDevicesArrayAdapter.add("没有搜索到设备");                  }              }            }  };

4.建立连接
查找到设备后，则需要建立本机与其他设备之间的连接。
一般用本机搜索其他蓝牙设备时，本机可以作为一个服务端，接收其他设备的连接。
启动一个服务器端的线程，死循环等待客户端的连接，这与ServerSocket极为相似。
这个线程在准备连接之前启动

//UUID可以看做一个端口号  private static final UUID MY_UUID =          UUID.fromString("fa87c0d0-afac-11de-8a39-0800200c9a66");     //像一个服务器一样时刻监听是否有连接建立      private class AcceptThread extends Thread{          private BluetoothServerSocket serverSocket;                    public AcceptThread(boolean secure){              BluetoothServerSocket temp = null;              try {                  temp = mBluetoothAdapter.listenUsingRfcommWithServiceRecord(                              NAME_INSECURE, MY_UUID);              } catch (IOException e) {                    Log.e("app", "listen() failed", e);              }              serverSocket = temp;          }                    public void run(){              BluetoothSocket socket=null;              while(true){                  try {                      socket = serverSocket.accept();                  } catch (IOException e) {                       Log.e("app", "accept() failed", e);                       break;                  }              }              if(socket!=null){                  //此时可以新建一个数据交换线程，把此socket传进去              }          }                    //取消监听          public void cancel(){                 try {                  serverSocket.close();              } catch (IOException e) {                  Log.e("app", "Socket Type" + socketType + "close() of server failed", e);              }          }    }

搜索到设备后可以获取设备的地址，通过此地址获取一个BluetoothDeviced对象，可以看做客户端，通过此对象device.createRfcommSocketToServiceRecord(MY_UUID);同一个UUID可与服务

器建立连接获取另一个socket对象，由此服务端与客户端各有一个socket对象，此时
他们可以互相交换数据了。
创立客户端socket可建立线程

//另一个设备去连接本机,相当于客户端   private class ConnectThread extends Thread{      private BluetoothSocket socket;      private BluetoothDevice device;      public ConnectThread(BluetoothDevice device,boolean secure){          this.device = device;          BluetoothSocket tmp = null;          try {      tmp = device.createRfcommSocketToServiceRecord(MY_UUID_SECURE);  } catch (IOException e) {       Log.e("app", "create() failed", e);  }      }            public void run(){          mBluetoothAdapter.cancelDiscovery();    //取消设备查找          try {      socket.connect();  } catch (IOException e) {      try {          socket.close();      } catch (IOException e1) {           Log.e("app", "unable to close() "+                            " socket during connection failure", e1);      }      connetionFailed();  //连接失败      return;  }        //此时可以新建一个数据交换线程，把此socket传进去      }              public void cancel() {             try {                 socket.close();             } catch (IOException e) {                 Log.e("app", "close() of connect  socket failed", e);             }         }   }

5.建立数据通信线程，进行读取数据

//建立连接后，进行数据通信的线程      private class ConnectedThread extends Thread{          private BluetoothSocket socket;          private InputStream inStream;          private OutputStream outStream;                    public ConnectedThread(BluetoothSocket socket){                            this.socket = socket;              try {                  //获得输入输出流                  inStream = socket.getInputStream();                  outStream = socket.getOutputStream();              } catch (IOException e) {                  Log.e("app", "temp sockets not created", e);              }          }                    public void run(){              byte[] buff = new byte[1024];              int len=0;              //读数据需不断监听，写不需要              while(true){                  try {                      len = inStream.read(buff);                      //把读取到的数据发送给UI进行显示                      Message msg = handler.obtainMessage(BluetoothChat.MESSAGE_READ,                              len, -1, buff);                      msg.sendToTarget();                  } catch (IOException e) {                      Log.e("app", "disconnected", e);                      connectionLost();   //失去连接                      start();    //重新启动服务器                      break;                  }              }          }                              public void write(byte[] buffer) {              try {                  outStream.write(buffer);                    // Share the sent message back to the UI Activity                  handler.obtainMessage(BluetoothChat.MESSAGE_WRITE, -1, -1, buffer)                          .sendToTarget();              } catch (IOException e) {                  Log.e("app", "Exception during write", e);              }          }            public void cancel() {              try {                  socket.close();              } catch (IOException e) {                  Log.e("app", "close() of connect socket failed", e);              }          }      }

蓝牙基本操作完成，要对socket有一定认识的童鞋才能够熟练操作。

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