保存的文件有4个：
checkpoint
model-parameters.bin-46000.data-00000-of-00001
model-parameters.bin-46000.index
model-parameters.bin-46000.meta
读取代码：
from tensorflow.python import pywrap_tensorflow
with tf.Graph().as_default():
with tf.Session() as sess:
ckpt = tf.train.get_checkpoint_state('./checkpoint
