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 //Localのファイルを一行ずつ読み込む方法
 void readFileByLines() {
  File file = new File('./assets/user.json');

  // async
  file.readAsLines().then((lines) =>
    lines.forEach((l) => print(l))
  );

  // sync
  List<String> lines = file.readAsLinesSync();
  lines.forEach((l) => print(l));
}
 
  //Web上のファイルを一行ずつ読み込む方法
  void downloadTextFileAndGetContentsLineByLine(String url) {
    HttpClient client = new HttpClient();
    client.getUrl(Uri.parse(url)).then((HttpClientRequest request) {
      return request.close();
    }).then((HttpClientResponse response) {
      response
          .transform(utf8.decoder)
          .transform(const LineSplitter())//行に分ける
          .listen((data) => print(data));
    });
  }



void downloadTextFileAndPrint() {
  HttpClient client = new HttpClient();
  client.getUrl(Uri.parse("https://fluttermaster.com/"))
      .then((HttpClientRequest request) {
    return request.close();
  })
      .then((HttpClientResponse response) {
    response.transform(utf8.decoder).listen((contents) => print(contents));
  });
}

void downloadTextFileAndSave() {
  HttpClient client = new HttpClient();
  var _downloadData = StringBuffer();
  var fileSave = new File('./index.html');
  client.getUrl(Uri.parse("https://fluttermaster.com/"))
      .then((HttpClientRequest request) {
    return request.close();
  })
      .then((HttpClientResponse response) {
    response.transform(utf8.decoder).listen((d) => _downloadData.write(d),
        onDone: () {
          fileSave.writeAsString(_downloadData.toString());
        }
    );
  });
}

void downloadBinaryFile() {
  HttpClient client = new HttpClient();
  var _downloadData = List<int>();
  var fileSave = new File('./logo.png');
  client.getUrl(Uri.parse("https://fluttermaster.com/wp-content/uploads/2018/08/fluttermaster.com-logo-web-header.png"))
      .then((HttpClientRequest request) {
    return request.close();
  })
      .then((HttpClientResponse response) {
    response.listen((d) => _downloadData.addAll(d),
        onDone: () {
          fileSave.writeAsBytes(_downloadData);
        }
    );
  });
}

void downloadFileUsingStreamPipe() {
  HttpClient client = new HttpClient();
  client.getUrl(Uri.parse("https://fluttermaster.com/wp-content/uploads/2018/08/fluttermaster.com-logo-web-header.png"))
      .then((HttpClientRequest request) {
    return request.close();
  })
      .then((HttpClientResponse response) {
    response.pipe(new File('./logo_pipe.png').openWrite());
  });
}