download method

@override Future<Response> download(String urlPath, dynamic savePath, { ProgressCallback? onReceiveProgress, Map<String, dynamic>? queryParameters, CancelToken? cancelToken, bool deleteOnError = true, String lengthHeader = Headers.contentLengthHeader, dynamic data, Options? options, })

Download the file and save it in local. The default http method is 'GET', you can custom it by Options.method.

urlPath: The file url.

savePath: The path to save the downloading file later. it can be a String or a callback:

1. A path with String type, eg 'xs.jpg'
2. A callback String Function(HttpHeaders responseHeaders); for example:

 await dio.download(url,(HttpHeaders responseHeaders){
    ...
    return '...';
  });

onReceiveProgress: The callback to listen downloading progress. please refer to ProgressCallback.

deleteOnError Whether delete the file when error occurs. The default value is true.

lengthHeader : The real size of original file (not compressed). When file is compressed:

1. If this value is 'content-length', the total argument of onProgress will be -1
2. If this value is not 'content-length', maybe a custom header indicates the original file size , the total argument of onProgress will be this header value.

you can also disable the compression by specifying the 'accept-encoding' header value as '*' to assure the value of total argument of onProgress is not -1. for example:

await dio.download(url, './example/flutter.svg',
options: Options(headers: {HttpHeaders.acceptEncodingHeader: '*'}),  // disable gzip
onProgress: (received, total) {
  if (total != -1) {
   print((received / total * 100).toStringAsFixed(0) + '%');
  }
});

Implementation

@override
Future<Response> download(
  String urlPath,
  savePath, {
  ProgressCallback? onReceiveProgress,
  Map<String, dynamic>? queryParameters,
  CancelToken? cancelToken,
  bool deleteOnError = true,
  String lengthHeader = Headers.contentLengthHeader,
  data,
  Options? options,
}) async {
  throw UnsupportedError('Unsupport download API in browser');
}