Question

我从抖动的http服务器发送图像文件作为Http响应时遇到问题。当代码看似可行时，该映像将以正确的名称下载到客户端，但已损坏且无法打开。很多时候，客户端会引发异常：Failed decoding image. Data is either invalid, or it is encoded using an unsupported format.已经在多个图像和物理设备上进行了测试。

在局域网上的两个android设备上串联使用此代码，目标IP已为其中一个设备进行了硬编码。（有关如何通过广播或其他方式获取该IP的建议，将不胜感激：）

服务器：

Future _startWebServer() async {
  runZoned(() {
    String requestString;
    HttpServer.bind(InternetAddress.anyIPv4, 8080).then((server) {
      server.transform(HttpBodyHandler()).listen((HttpRequestBody body) async {
        requestString = utf8.decode(body.body);
        switch (requestString) {
          case 'fileName':
            {
              body.request.response.write(basename(_imageFile.path));
              body.request.response.close();
              break;
            }
          case 'file':
            {
              body.request.response.write(_imageFile.readAsBytesSync());
              body.request.response.close();
              break;
            }
          default:
            {
              body.request.response.write('hello from server!');
              body.request.response.close();
            }
        }
      });
    });
  },
    onError: (e, stackTrace) => print('Oh No! $e $stackTrace'));
}

客户端：

File _imageFile;
void _receiveData() async {
  String fileName = "FILE1";
  HttpClient client = new HttpClient();
  await client.getUrl(Uri.parse("http://192.168.1.11:8080"))
    .then((HttpClientRequest request) {
      request.headers.contentLength = utf8.encode('fileName').length;
      request.write('fileName');
     return request.close();
  })
  .then((HttpClientResponse response) {
    response.transform(utf8.decoder).listen((contents){
      centerText = contents;
      fileName = contents;
    });
    setState(() {});
  });
  Directory tempDir = await getExternalStorageDirectory();
  var fileSave = new File(tempDir.path + '/' + fileName);
  var _downloadedData = List<int>();
  await client.getUrl(Uri.parse("http://192.168.1.11:8080"))
      .then((HttpClientRequest request) {
    request.headers.contentLength = utf8.encode('file').length;
    request.write('file');
    return request.close();
  })
      .then((HttpClientResponse response) async {
    print('Received file');
    //------------------Decode error here-----------------
    response.listen((d) => _downloadedData.addAll(d),
    onDone:(){
      fileSave.writeAsBytes(_downloadedData);
    });

    setState(() {
    _imageFile = fileSave;
    });
  });
  client.close();
}

对于问题或整个代码的任何建议，评论和评论，我们将不胜感激。谢谢！

Answer 1

没有意识到body.request.response.write()将_imageFile.readAsBytesSync() as List<int>转换为字符串。通过将body.request.response.write(_imageFile.readAsBytesSync());更改为body.request.response.add(_imageFile.readAsBytesSync());

进行了修复

.add将List<int>“添加”到响应正文。

使用Flutter通过HTTP连接发送文件时出现问题

1 个答案: