How works sendCommand?

问题

I don't understand sendCommand I have to convert a string to byte to execute in this code

public void sendCommand(byte command) 
   throws IOException, IllegalArgumentException

Sends a command byte to the remote peer, adding the IAC prefix. This method does not wait for any response. Messages sent by the remote end can be handled by registering an appropriate TelnetOptionHandler.

Parameters: command - the code for the command

来源：https://stackoverflow.com/questions/17926779/how-works-sendcommand