Pythonflask框架如何显示图像到web页面

from flask import Flask
from flask import render_template
import matplotlib.pyplot as plt
import io
import base64

app = Flask(__name__)

@app.route('/')
def build_plot():
  img = io.BytesIO()
  y = [1,2,3,4,5]
  x = [0,2,1,3,4]
  plt.plot(x,y)
  plt.savefig(img, format='png')
  img.seek(0)

  plot_url = base64.b64encode(img.getvalue()).decode()

  return render_template('plot.html', plot_url=plot_url)

if __name__ == '__main__':
  app.debug = True
  app.run()