1 损失函数得这样定义才行
2 training训练的时候True，预测的时候False
out = tf.layers.batch_normalization(out, training=is_training)
update_ops = tf.get_collection(tf.GraphKeys.UPDATE_OPS)
with tf.control_dependencies(update_ops):
cross_entropy = tf.reduce_mean( tf.nn.softmax_cross_entropy_with_logits_v2(labels=y,logits=out) )