模型保存，先要创建一个Saver对象：如
saver=tf.train.Saver()
在创建这个Saver对象的时候，有一个参数我们经常会用到，就是 max_to_keep 参数，这个是用来设置保存模型的个数，默认为5，即 max_to_keep=5，保存最近的5个模型。如果你想每训练一代（epoch)就想保存一次模型，则可以将 max_to_keep设置为None或者0，如：
saver=tf.train.Saver(max_to_keep=0)
但是这样做除了多占用硬盘，并没有实际多大的用处，因此不推荐。
当然，如果你只想保存最后一代的模型，则只需要将max_to_keep设置为1即可，即
saver=tf.train.Saver(max_to_keep=1)
创建完saver对象后，就可以保存训练好的模型了，如：
saver.save(sess,'ckpt/mnist.ckpt',global_step=step)
第一个参数sess,这个就不用说了。第二个参数设定保存的路径和名字，第三个参数将训练的次数作为后缀加入到模型名字中。
saver.save(sess, 'my-model', global_step=0) ==> filename: 'my-model-0'
... saver.save(sess, 'my-model', global_step=1000) ==> filename: 'my-model-1000'看一个mnist实例：
# -*- coding: utf-8 -*-"""Created on Sun Jun 4 10:29:48 2017@author: Administrator"""import tensorflow as tffrom tensorflow.examples.tutorials.mnist import input_datamnist = input_data.read_data_sets("MNIST_data/", one_hot=False)x = tf.placeholder(tf.float32, [None, 784])y_=tf.placeholder(tf.int32,[None,])dense1 = tf.layers.dense(inputs=x, units=1024, activation=tf.nn.relu, kernel_initializer=tf.truncated_normal_initializer(stddev=0.01), kernel_regularizer=tf.nn.l2_loss)dense2= tf.layers.dense(inputs=dense1, units=512, activation=tf.nn.relu, kernel_initializer=tf.truncated_normal_initializer(stddev=0.01), kernel_regularizer=tf.nn.l2_loss)logits= tf.layers.dense(inputs=dense2, units=10, activation=None, kernel_initializer=tf.truncated_normal_initializer(stddev=0.01), kernel_regularizer=tf.nn.l2_loss)loss=tf.losses.sparse_softmax_cross_entropy(labels=y_,logits=logits)train_op=tf.train.AdamOptimizer(learning_rate=0.001).minimize(loss)correct_prediction = tf.equal(tf.cast(tf.argmax(logits,1),tf.int32), y_) acc= tf.reduce_mean(tf.cast(correct_prediction, tf.float32))sess=tf.InteractiveSession() sess.run(tf.global_variables_initializer())saver=tf.train.Saver(max_to_keep=1)for i in range(100): batch_xs, batch_ys = mnist.train.next_batch(100) sess.run(train_op, feed_dict={x: batch_xs, y_: batch_ys}) val_loss,val_acc=sess.run([loss,acc], feed_dict={x: mnist.test.images, y_: mnist.test.labels}) print('epoch:%d, val_loss:%f, val_acc:%f'%(i,val_loss,val_acc)) saver.save(sess,'ckpt/mnist.ckpt',global_step=i+1)sess.close() 代码中红色部分就是保存模型的代码，虽然我在每训练完一代的时候，都进行了保存，但后一次保存的模型会覆盖前一次的，最终只会保存最后一次。因此我们可以节省时间，将保存代码放到循环之外（仅适用max_to_keep=1,否则还是需要放在循环内).
在实验中，最后一代可能并不是验证精度最高的一代，因此我们并不想默认保存最后一代，而是想保存验证精度最高的一代，则加个中间变量和判断语句就可以了。
saver=tf.train.Saver(max_to_keep=1)max_acc=0for i in range(100): batch_xs, batch_ys = mnist.train.next_batch(100) sess.run(train_op, feed_dict={x: batch_xs, y_: batch_ys}) val_loss,val_acc=sess.run([loss,acc], feed_dict={x: mnist.test.images, y_: mnist.test.labels}) print('epoch:%d, val_loss:%f, val_acc:%f'%(i,val_loss,val_acc)) if val_acc>max_acc: max_acc=val_acc saver.save(sess,'ckpt/mnist.ckpt',global_step=i+1)sess.close() 如果我们想保存验证精度最高的三代，且把每次的验证精度也随之保存下来，则我们可以生成一个txt文件用于保存。
saver=tf.train.Saver(max_to_keep=3)max_acc=0f=open('ckpt/acc.txt','w')for i in range(100): batch_xs, batch_ys = mnist.train.next_batch(100) sess.run(train_op, feed_dict={x: batch_xs, y_: batch_ys}) val_loss,val_acc=sess.run([loss,acc], feed_dict={x: mnist.test.images, y_: mnist.test.labels}) print('epoch:%d, val_loss:%f, val_acc:%f'%(i,val_loss,val_acc)) f.write(str(i+1)+', val_acc: '+str(val_acc)+'\n') if val_acc>max_acc: max_acc=val_acc saver.save(sess,'ckpt/mnist.ckpt',global_step=i+1)f.close()sess.close()
模型的恢复用的是restore()函数，它需要两个参数restore(sess, save_path)，save_path指的是保存的模型路径。我们可以使用tf.train.latest_checkpoint（）来自动获取最后一次保存的模型。如：
model_file=tf.train.latest_checkpoint('ckpt/')saver.restore(sess,model_file) 则程序后半段代码我们可以改为：
sess=tf.InteractiveSession() sess.run(tf.global_variables_initializer())is_train=Falsesaver=tf.train.Saver(max_to_keep=3)#训练阶段if is_train: max_acc=0 f=open('ckpt/acc.txt','w') for i in range(100): batch_xs, batch_ys = mnist.train.next_batch(100) sess.run(train_op, feed_dict={x: batch_xs, y_: batch_ys}) val_loss,val_acc=sess.run([loss,acc], feed_dict={x: mnist.test.images, y_: mnist.test.labels}) print('epoch:%d, val_loss:%f, val_acc:%f'%(i,val_loss,val_acc)) f.write(str(i+1)+', val_acc: '+str(val_acc)+'\n') if val_acc>max_acc: max_acc=val_acc saver.save(sess,'ckpt/mnist.ckpt',global_step=i+1) f.close()#验证阶段else: model_file=tf.train.latest_checkpoint('ckpt/') saver.restore(sess,model_file) val_loss,val_acc=sess.run([loss,acc], feed_dict={x: mnist.test.images, y_: mnist.test.labels}) print('val_loss:%f, val_acc:%f'%(val_loss,val_acc))sess.close() 标红的地方，就是与保存、恢复模型相关的代码。用一个bool型变量is_train来控制训练和验证两个阶段。
整个源程序：
# -*- coding: utf-8 -*-"""Created on Sun Jun 4 10:29:48 2017@author: Administrator"""import tensorflow as tffrom tensorflow.examples.tutorials.mnist import input_datamnist = input_data.read_data_sets("MNIST_data/", one_hot=False)x = tf.placeholder(tf.float32, [None, 784])y_=tf.placeholder(tf.int32,[None,])dense1 = tf.layers.dense(inputs=x, units=1024, activation=tf.nn.relu, kernel_initializer=tf.truncated_normal_initializer(stddev=0.01), kernel_regularizer=tf.nn.l2_loss)dense2= tf.layers.dense(inputs=dense1, units=512, activation=tf.nn.relu, kernel_initializer=tf.truncated_normal_initializer(stddev=0.01), kernel_regularizer=tf.nn.l2_loss)logits= tf.layers.dense(inputs=dense2, units=10, activation=None, kernel_initializer=tf.truncated_normal_initializer(stddev=0.01), kernel_regularizer=tf.nn.l2_loss)loss=tf.losses.sparse_softmax_cross_entropy(labels=y_,logits=logits)train_op=tf.train.AdamOptimizer(learning_rate=0.001).minimize(loss)correct_prediction = tf.equal(tf.cast(tf.argmax(logits,1),tf.int32), y_) acc= tf.reduce_mean(tf.cast(correct_prediction, tf.float32))sess=tf.InteractiveSession() sess.run(tf.global_variables_initializer())is_train=Truesaver=tf.train.Saver(max_to_keep=3)#训练阶段if is_train: max_acc=0 f=open('ckpt/acc.txt','w') for i in range(100): batch_xs, batch_ys = mnist.train.next_batch(100) sess.run(train_op, feed_dict={x: batch_xs, y_: batch_ys}) val_loss,val_acc=sess.run([loss,acc], feed_dict={x: mnist.test.images, y_: mnist.test.labels}) print('epoch:%d, val_loss:%f, val_acc:%f'%(i,val_loss,val_acc)) f.write(str(i+1)+', val_acc: '+str(val_acc)+'\n') if val_acc>max_acc: max_acc=val_acc saver.save(sess,'ckpt/mnist.ckpt',global_step=i+1) f.close()#验证阶段else: model_file=tf.train.latest_checkpoint('ckpt/') saver.restore(sess,model_file) val_loss,val_acc=sess.run([loss,acc], feed_dict={x: mnist.test.images, y_: mnist.test.labels}) print('val_loss:%f, val_acc:%f'%(val_loss,val_acc))sess.close() 参考文章：http://blog.csdn.net/u011500062/article/details/51728830