java Netty 4.0：检测Websocket握手是否完成

Question

我想重构一个旧的Netty 3。将websocket服务器升级到新版本4.0。Websocket握手完成后，我需要向客户发送“欢迎信息”。也许有人能给我一个提示，如何在websocket连接准备就绪后立即通知我？我在玩websocket server example

Answer 1

如果Websocket握手完成，Netty将引发一个用户事件

见https://github.com/netty/netty/blob/netty-4.1.51.Final/codec-http/src/main/java/io/netty/handler/codec/http/websocketx/WebSocketServerProtocolHandshakeHandler.java#L101

Netty 4.0中的UserEvent是WebSocketServerProtocolHandler.ServerHandshakeStateEvent.HANDSHAKE_COMPLETE，Netty 4.1中的UserEvent是WebSocketServerProtocolHandler.HandshakeComplete

您可以在WebSocketHandler中重写userEventTriggered方法：

public class WebSocketFrameHandler extends SimpleChannelInboundHandler<WebSocketFrame> {

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, WebSocketFrame frame) {
        if (frame instanceof TextWebSocketFrame) {
            // Send the uppercase string back.
            String request = ((TextWebSocketFrame) frame).text();
            ctx.channel().writeAndFlush(new TextWebSocketFrame(request.toUpperCase()));
        } else {
            String message = "unsupported frame type: " + frame.getClass().getName();
            throw new UnsupportedOperationException(message);
        }
    }

    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        if (evt instanceof WebSocketServerProtocolHandler.HandshakeComplete) {
            WebSocketServerProtocolHandler.HandshakeComplete complete = (WebSocketServerProtocolHandler.HandshakeComplete) evt;
            System.out.println("New WebSocket handshake complete, uri:" + complete.requestUri());
        } else {
            super.userEventTriggered(ctx, evt);
        }
    }
}

Answer 2

WebSocketServerHandshaker.handshake()返回一个ChannelFuture，在握手完成时收到通知