private String doRegister(String key) { if (server.getKeys().contains(key)) { return "fail to register key, key [" + key + "] has already been registered before"; } server.getKeys().add(key); return "key [" + key + "] has registered"; }
boolean isKeyRegistered(String key) { return server.getKeys().contains(key); }
private String doUnregister(String key) { server.getKeys().remove(key); return "key [" + key + "] has unregistered"; }