Django使用中间件解决前后端同源策略问题

Failed to load http://127.0.0.1:8888/publisher/: 
No 'Access-Control-Allow-Origin' header is present on the requested resource. 
Origin 'http://localhost:4200' is therefore not allowed access.

private publishersUrl = 'http://127.0.0.1:8888/publisher/';
private addpubUrl = 'http://127.0.0.1:8888/addpub/';
getPublishers (): Observable<Publisher[]> {
  return this.http.get<Publisher[]>(this.publishersUrl)
  .pipe(
   catchError(this.handleError<Publisher[]>('getPublishers', []))
  ); 
}

from django.utils.deprecation import MiddlewareMixin
class MyCore(MiddlewareMixin):
  def process_response(self, request, response):
    response['Access-Control-Allow-Origin'] = "*"
    if request.method == "OPTIONS":
      # 复杂请求 预检
      response['Access-Control-Allow-Headers'] = "Content-Type"
      response['Access-Control-Allow-Methods'] = "POST, DELETE, PUT"
    return response

MIDDLEWARE = [
  'BMS.myMiddleware.MyCore',
]