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android - 使用颤振通过http连接发送文件的问题

问题描述

我在从颤动的 http 服务器发送图像文件作为 Http 响应时遇到问题。当代码看似有效时，图像会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，客户端会抛出异常：Failed decoding image. Data is either invalid, or it is encoded using an unsupported format.这已经在多个图像和物理设备上进行了测试。

在 LAN 网络上的两个 android 设备上串联使用此代码，目标 IP 被硬编码用于其中一个设备。（有关如何从广播中获取该 IP 或其他内容的建议将不胜感激：）

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：

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();
}

对问题或一般代码的任何建议、批评和评论将不胜感激。谢谢！

标签： androidhttpflutterdartserver

解决方案

没有意识到body.request.response.write()将其转换_imageFile.readAsBytesSync() as List<int>为字符串。body.request.response.write(_imageFile.readAsBytesSync());通过更改为修复body.request.response.add(_imageFile.readAsBytesSync());

.add “添加” aList<int>到响应正文。

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