看起来您实际上并没有为LSTM层提供输入.您指定了复发神经元的数量和输入的 shape ，但未提供输入.试试:

It looks like you're not actually giving an input to your LSTM layer. You specify the number of recurrent neurons and the shape of the input, but do not provide an input. Try:

lstm_out = LSTM(128, input_shape=(maxlen, len(chars)))(net_input)