[英]Android Bluetooth Read InputStream
我正在嘗試讀取從外部藍牙模塊發送到我的HTC Sensation的串行數據,但是當我調用InputStream.available()時 - 它返回0,所以我不能迭代收到的字節並調用InputStream.read(byteArray)。
有人可以幫我解決這個問題嗎?
在閱讀之前我需要檢查可用字節嗎?
我為技術上不准確的帖子道歉。
這是我的代碼:
public class BluetoothTest extends Activity
{
TextView myLabel;
TextView snapText;
EditText myTextbox;
BluetoothAdapter mBluetoothAdapter;
BluetoothSocket mmSocket;
BluetoothDevice mmDevice;
OutputStream mmOutputStream;
InputStream mmInputStream;
Thread workerThread;
byte[] readBuffer;
int readBufferPosition;
int counter;
volatile boolean stopWorker;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button openButton = (Button)findViewById(R.id.open);
Button closeButton = (Button)findViewById(R.id.close);
Button chkCommsButton = (Button)findViewById(R.id.chkCommsButton);
Button offButton = (Button)findViewById(R.id.offButton);
myLabel = (TextView)findViewById(R.id.mylabel);
snapText = (TextView)findViewById(R.id.snapText);
//Open Bluetooth
openButton.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
try
{
findBT();
openBT();
}
catch (IOException ex) { }
}
});
//Close Bluetooth
closeButton.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
try
{
closeBT();
}
catch (IOException ex) { }
}
});
// Check Comms - multicast all SNAP nodes and pulse their BLUE led
chkCommsButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
chkcommsButton();
} catch (Exception e) {
// TODO: handle exception
}
}
});
//Off Button - set strip to all OFF
offButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
offButton();
} catch (Exception e) {
// TODO: handle exception
}
}
});
}
void findBT()
{
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if(mBluetoothAdapter == null)
{
myLabel.setText("No bluetooth adapter available");
}
if(!mBluetoothAdapter.isEnabled())
{
Intent enableBluetooth = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBluetooth, 0);
}
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
if(pairedDevices.size() > 0)
{
for(BluetoothDevice device : pairedDevices)
{
if(device.getName().equals("BTNODE25")) // Change to match RN42 - node name
{
mmDevice = device;
Log.d("ArduinoBT", "findBT found device named " + mmDevice.getName());
Log.d("ArduinoBT", "device address is " + mmDevice.getAddress());
break;
}
}
}
myLabel.setText("Bluetooth Device Found");
}
void openBT() throws IOException
{
UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb"); //Standard SerialPortService ID
mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);
mmSocket.connect();
mmOutputStream = mmSocket.getOutputStream();
mmInputStream = mmSocket.getInputStream();
beginListenForData();
myLabel.setText("BT << " + mmDevice.getName() + " >> is now open ");
}
void closeBT() throws IOException
{
stopWorker = true;
mmOutputStream.close();
mmInputStream.close();
mmSocket.close();
myLabel.setText("Bluetooth Closed");
}
void beginListenForData()
{
final Handler handler = new Handler();
final byte delimiter = 10; //This is the ASCII code for a newline character
stopWorker = false;
readBufferPosition = 0;
readBuffer = new byte[1024];
workerThread = new Thread(new Runnable()
{
public void run()
{
while(!Thread.currentThread().isInterrupted() && !stopWorker)
{
try
{
int bytesAvailable = mmInputStream.available();
if(bytesAvailable > 0)
{
byte[] packetBytes = new byte[bytesAvailable];
mmInputStream.read(packetBytes);
for(int i=0;i<bytesAvailable;i++)
{
byte b = packetBytes[i];
if(b == delimiter)
{
byte[] encodedBytes = new byte[readBufferPosition];
System.arraycopy(readBuffer, 0, encodedBytes, 0, encodedBytes.length);
final String data = new String(encodedBytes, "US-ASCII");
readBufferPosition = 0;
handler.post(new Runnable()
{
public void run()
{
snapText.setText(data);
}
});
}
else
{
readBuffer[readBufferPosition++] = b;
}
}
}
}
catch (IOException ex)
{
stopWorker = true;
}
}
}
});
workerThread.start();
}
void offButton() throws IOException
{
mmOutputStream.write("0".getBytes());
}
void chkcommsButton() throws IOException
{
mmOutputStream.write("1".getBytes());
}
}
InputStream.read()
方法是阻塞的,這意味着它會阻塞你的代碼,直到一些數據到達,或者某些東西破壞管道(如斷開主機或關閉流)。 阻塞是CPU友好的,因為線程處於WAIT狀態(休眠),直到中斷使其處於READY狀態,因此它將被安排在CPU上運行; 所以你在等待數據時WONT使用cpu,這意味着你將使用更少的電池(或者你將CPU時間留給其他人的線程)!
available()
給出了實際可用的數據,並且因為串行通信非常慢(11n00波特在8n1意味着11520字節/秒)並且你的循環運行速度至少快一到兩個數量級,你會讀到很多0,並且使用大量的cpu來要求零......這意味着你要使用大量的電池。
循環可用在arduino上不是問題,因為你只有一個線程/進程:你的代碼。 但是在多線程系統中循環檢查數據(稱為“輪詢”)總是一個壞主意,並且只有在你沒有其他選擇時才應該完成,並且總是添加一點sleep()以便你的代碼贏得' t竊取CPU到系統和其他線程。 好主意是使用阻塞調用(對於初學者來說很容易使用)或者像你對圖形事件那樣使用事件系統(並不總是被你使用的庫支持,並且需要同步,所以它很棘手,但你不會產生其他線程你自己的代碼,但請記住,串行和圖形的數據和你的應用程序PROBABLY在不同的線程中,應該同步)
您正在使用
import java.util.logging.Handler;
將其更改為
import android.os.Handler;
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