Upload file via WebSocket (BinaryWebSocketFrame) and Netty

Question

I'm trying to upload a file via websockets with the following code:

let file = e.target.files[0]
let ws = new WebSocket("ws://127.0.0.1:8080/")
ws.binaryType = "arraybuffer";

var reader = new FileReader();
var rawData = new ArrayBuffer();

ws.onopen = () => {

    reader.loadend = function() {}

    reader.onload = function(e) {
        rawData = e.target.result;
        ws.send(rawData);
        console.log("Transfer complete.")
    }

    reader.readAsArrayBuffer(file);

}

The websocket works with texts well, and the connection is definitly not the problem. But coming to the very detailed netty documentation, I cannot find anything how to handle the recieved BinaryWebSocketFrame. Here the java code:

public class SocketHandler extends SimpleChannelInboundHandler<Object> {

    @Override
    public void messageReceived(ChannelHandlerContext ctx, Object msg) throws Exception {

        if (msg instanceof WebSocketFrame) {

            if (msg instanceof BinaryWebSocketFrame) {

                System.out.println("BinaryWebSocketFrame Received : ");
                BinaryWebSocketFrame frame = (BinaryWebSocketFrame) msg;

                //This is nothing more than an echo.. It is received by the client successfully.
                ctx.writeAndFlush(new BinaryWebSocketFrame(frame.isFinalFragment(), frame.rsv(), frame.content()));

            } else if (msg instanceof TextWebSocketFrame) {

                System.out.println("TextWebSocketFrame Received : " + ((TextWebSocketFrame) msg).text());

            }

        }

    }

}

My problem is the BinaryWebSocketFrame.. how can I store it to a file now? Or what is contained in this bytebuf? Can I store the path where the file should be stored inside the buf? I'm not good with ByteBuffers, so please go in detail.. there is no documentation on this things happening in netty.

Norman Maurer · Accepted Answer · 2018-02-15 12:34:19Z

2

The BinaryWebSocketFrame.content() method returns a ByteBuf. The ByteBuf methods has a readBytes(...) method that takes an OutputStream which you could use to write to a file.

answered Feb 15, 2018 at 12:34

Norman Maurer

23.7k2 gold badges35 silver badges31 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Felix Gaebler Over a year ago

can you maybe add some example code? e.g. hat are the parameters of readBytes

Felix Gaebler · Accepted Answer · 2018-02-16 20:09:00Z

2

I found it out... here is an code example in addition

BinaryWebSocketFrame frame = (BinaryWebSocketFrame) msg;
ByteBuf buffer = frame.content().retain();
FileOutputStream outputStream = new FileOutputStream(new File("test.png"));

try {

    if (buffer.isReadable()) {
        buffer.readBytes(outputStream, buffer.readableBytes());
    }

} finally {
    outputStream.close();
}

answered Feb 16, 2018 at 20:09

Felix Gaebler

7434 silver badges25 bronze badges

Collectives™ on Stack Overflow

Upload file via WebSocket (BinaryWebSocketFrame) and Netty

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related