FastAPI 通过中间件实现JWT鉴权

1、实现login路由白名单获取Token

2、对非白名单的路由进行鉴权

 2.1 检查headers里是否包含鉴权信息

 2.2 检查是否Token过期或非法Token

安装pyjwt包 pip install pyjwt 'passlib[bcrypt]'

实现JWT 生成和解码类

class AuthHandle():

    security=HTTPBearer()
    pwd_context=CryptContext(schemes=['bcrypt'],deprecated='auto')
    secret=settings.JWT_SECRET_KEY

    # 生成Token
    async def encode_token(self,user_id:int)->str:
      payload= {
         'exp': datetime.now()+timedelta(days=0,minutes=120),
         'sub': str(user_id)
      }

      return jwt.encode(payload,self.secret,algorithm='HS256')

    # 验证Token
    async def decode_token(self,token):
        try:
            payload=jwt.decode(token,self.secret,algorithms=['HS256'])
            return payload['sub']
        except jwt.ExpiredSignatureError:
            raise AuthException(message='令牌已过期')
        except jwt.InvalidTokenError:
            raise AuthException(message='无效令牌')


    # 异常类
 class AuthException(Exception):
     def __init__(self,message):
         super().__init__(message)

中间件过滤白名单  WHITE_LIST=['/user/login']

from settings import WHITE_LIST,TOKEN_INVALID_ERROR

class TokenMiddleware(BaseHTTPMiddleware):
    def __init__(self,app):
        super().__init__(app)

    async def dispatch(self,req:Request,call_next):

        # 不在白名单内 提示未授权
        if not req.url.path in WHITE_LIST: 
            # 需要通过JWT鉴权
            if 'Authorization' not in req.headers or not req.headers['Authorization']:
                return Response(content=json.dumps(TOKEN_INVALID_ERROR),status_code=status.HTTP_401_UNAUTHORIZED)
            # 去掉Bearer 
            token=req.headers['Authorization'][7:]
            auth=AuthHandle()
            try:
                await auth.decode_token(token)
            except AuthException as e:
                TOKEN_INVALID_ERROR['msg']=f'{e}'
                return Response(content=json.dumps(TOKEN_INVALID_ERROR),
                                status_code=status.HTTP_401_UNAUTHORIZED
                                )

最终在app.add_middleware(TokenMiddleware)绑定实现