//添加拦截器
dio.interceptors.add(InterceptorsWrapper(onRequest: (options, handler) {
print("请求之前");
return handler.next(options);
}, onResponse: (response, hander) {
print("响应之前");
return hander.next(response);
}, onError: (DioError e, hanlder) {
print("错误之前");
handleError(e);
return hanlder.next(e);
}));
}