Python实现自定义读写分离代码实例

from flask import Flaskfrom flask_sqlalchemy import SQLAlchemy, SignallingSession, get_statefrom sqlalchemy import ormclass RoutingSession(SignallingSession):  def get_bind(self, mapper=None, clause=None):    state = get_state(self.app)    # 判断读写操作    if self._flushing: # 写操作 ,使用主数据库      print("写入数据")      return state.db.get_engine(self.app, bind='master')    else: # 读操作, 使用从数据库      print('读取数据')      return state.db.get_engine(self.app, bind='slave')class RoutingSQLAlchemy(SQLAlchemy):  def create_session(self, options):    return orm.sessionmaker(class_=RoutingSession, db=self, **options)app = Flask(__name__)# 设置数据库的连接地址app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://root:mysql@192.168.105.134:3306/demo'# 设置数据库的绑定地址app.config['SQLALCHEMY_BINDS'] = {  'master': "mysql://root:mysql@192.168.105.134:3306/demo",  'slave': "mysql://root:mysql@192.168.105.134:8306/demo"}# 设置是否追踪数据库变化  一般不会开启, 影响性能app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False# 设置是否打印底层执行的SQL语句app.config['SQLALCHEMY_ECHO'] = False# 创建数据库连接对象db = RoutingSQLAlchemy(app)# 用户表 一class User(db.Model):  __tablename__ = 't_user'  id = db.Column(db.Integer, primary_key=True)  name = db.Column(db.String(20), unique=True)@app.route('/')def index():  # 增加数据  user1 = User(name='zs')  db.session.add(user1)  db.session.commit()  # 查询数据  users = User.query.all()  print(users)  return "index"if __name__ == '__main__':  # 删除所有继承自db.Model的表  db.drop_all()  # 创建所有继承自db.Model的表  db.create_all()  app.run(debug=True)