Question

我试图将文本从客户端android发送到PC上的服务器java

这是android端代码

protected static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");

private String BluetoothMacAddress = "A8:A7:95:65:26:BA";
protected void onCreate() {
    initBluetoothDevice();
    CheckBluetoothState();
    device = mBluetoothAdapter.getRemoteDevice(getBluetoothMacAddress());
    new Send("Hello from Client").execute();
    mBluetoothAdapter.cancelDiscovery();
}

class Send extends AsyncTask<Void, Void, Void> {

    BluetoothSocket btSocket;
    //private Socket client;
    private String TextMessage;
    //private PrintWriter toServer;
    protected OutputStream outStream = null;
    public Send(String string) {
        TextMessage = string;
    }

    @Override
    protected Void doInBackground(Void... params) {
        try {
            Log.d(TAG, "doInBackground: "+TextMessage);
            //client = new Socket(IpAdress, Port); // connect to the server Ip given by my mobile hotspot
            btSocket = device.createRfcommSocketToServiceRecord(MY_UUID);
            btSocket.connect();

            outStream = btSocket.getOutputStream();
            byte[] msgBuffer = TextMessage.getBytes();
            outStream.write(msgBuffer);
            outStream.flush();
            btSocket.close(); // closing the connection

        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
}

这是java代码

public class SimpleSPPServer {
StreamConnection connection;
StreamConnectionNotifier streamConnNotifier;
InputStream inStream;
BufferedReader bReader;

private void startServer() throws IOException{

    //Create a UUID for SPP
    UUID uuid = new UUID("0001101", true);
    //Create the servicve url
    String connectionString = "btspp://localhost:" + uuid +";name=Sample SPP Server";

    //open server url
    streamConnNotifier = (StreamConnectionNotifier)Connector.open( connectionString );

    //Wait for client connection
    System.out.println("\nServer Started. Waiting for clients to connect...");
    connection = streamConnNotifier.acceptAndOpen();

    RemoteDevice dev = RemoteDevice.getRemoteDevice(connection);
    System.out.println("Remote device address: "+dev.getBluetoothAddress());
    System.out.println("Remote device name: "+dev.getFriendlyName(true));

    while(true){
        try{
            //streamConnNotifier = (StreamConnectionNotifier)Connector.open( connectionString );
            connection = streamConnNotifier.acceptAndOpen();

            inStream = connection.openInputStream();
            bReader=new BufferedReader(new InputStreamReader(inStream));
            String lineRead = bReader.readLine();
            System.out.println(lineRead);
        inStream.close();
    }catch(Exception e){
        e.printStackTrace();
        //  break;
    }
    }
}

}

代码有效，但问题是收到的消息有时为空，有人能告诉我问题在哪里以及如何修复

Answer 1

查看BufferedReader#readLine()的文档，它将以下内容指定为返回值：

包含行内容的字符串，不包括任何行终止字符;如果已到达流的末尾，则为null

因此，当它返回null时，表示基础数据流没有任何进一步的数据。通过蓝牙等两台计算机之间的任何通信，可能只是通信失败的情况，应该经常发生。

使用蓝牙从android到pc的短信有时被视为空

1 个答案: