获取java.io.IO异常：读取失败，套接字可能关闭或超时，通过蓝牙打印机打印时读取ret：-1

Question

代码仅在第一次正常工作，如果我试图再次连接它，它会抛出此异常：

读取失败，套接字可能已关闭或超时，读取重试：-1

这是我连接蓝牙打印机的功能：

public boolean openBT(Context context) throws IOException {
    try {
        // Standard SerialPortService ID
        UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");
        mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);
        mBluetoothAdapter.cancelDiscovery();

        mmSocket.connect();

        mmOutputStream = new DataOutputStream(mmSocket.getOutputStream());
        mmInputStream = new DataInputStream(mmSocket.getInputStream());


    } catch (NullPointerException e) {
        e.printStackTrace();
        return false;
    } catch (Exception e) { 
         e.printStackTrace();
        return false;

    }

    return true;

}

Answer 1

检查您的UUID，如果您不知道UUID，请尝试以下操作：

UUID uuidSting = null;
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1) {
    uuidSting = bluetoothDevice.getUuids()[0].getUuid();
}

而是使用：

UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");

Answer 2

使用后应关闭插座：

public boolean openBT(Context context) throws IOException {
try {
    // Standard SerialPortService ID
    UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");
    mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);
    mBluetoothAdapter.cancelDiscovery();

    mmSocket.connect();

    mmOutputStream = new DataOutputStream(mmSocket.getOutputStream());
    mmInputStream = new DataInputStream(mmSocket.getInputStream());

    mmSocket.close(); //Socket closed
} catch (NullPointerException e) {
    e.printStackTrace();
    return false;
} catch (Exception e) { 
     e.printStackTrace();
    return false;

}

return true;}