Python使用matplotlib绘图无法显示中文问题的解决方法

import matplotlib.pyplot as plt
# 定义文本框和箭头格式
decisionNode = dict(boxstyle = "sawtooth", fc = "0.8")
leafNode = dict(boxstyle = "round4", fc = "0.8")
arrow_args = dict(arrowstyle = "<-")
# 绘制带箭头的注解
def plotNode(nodeTxt, centerPt, parentPt, nodeType) :
  createPlot.ax1.annotate(nodeTxt, xy = parentPt, xycoords = 'axes fraction', xytext = centerPt, textcoords = 'axes fraction', va = 'center', ha = 'center', bbox = nodeType, arrowprops = arrow_args)
def createPlot() :
  fig = plt.figure(1, facecolor='white')
  fig.clf()
  createPlot.ax1 = plt.subplot(111, frameon = False)
  plotNode(U'决策节点', (0.5, 0.1), (0.1, 0.5), decisionNode)
  plotNode(U'叶节点', (0.8, 0.1), (0.3, 0.8), leafNode)
  plt.show()
createPlot()

from pylab import *
mpl.rcParams['font.sans-serif'] = ['SimHei']

import matplotlib.pyplot as plt
from pylab import *
mpl.rcParams['font.sans-serif'] = ['SimHei']
# 定义文本框和箭头格式
decisionNode = dict(boxstyle = "sawtooth", fc = "0.8")
leafNode = dict(boxstyle = "round4", fc = "0.8")
arrow_args = dict(arrowstyle = "<-")
# 绘制带箭头的注解
def plotNode(nodeTxt, centerPt, parentPt, nodeType) :
  createPlot.ax1.annotate(nodeTxt, xy = parentPt, xycoords = 'axes fraction', xytext = centerPt, textcoords = 'axes fraction', va = 'center', ha = 'center', bbox = nodeType, arrowprops = arrow_args)
def createPlot() :
  fig = plt.figure(1, facecolor='white')
  fig.clf()
  createPlot.ax1 = plt.subplot(111, frameon = False)
  plotNode(U'决策节点', (0.5, 0.1), (0.1, 0.5), decisionNode)
  plotNode(U'叶节点', (0.8, 0.1), (0.3, 0.8), leafNode)
  plt.show()
createPlot()