HelloWorldHttp2Handler Class — netty Architecture

Source Code

example/src/main/java/io/netty/example/http2/helloworld/server/HelloWorldHttp2Handler.java lines 43–166

public final class HelloWorldHttp2Handler extends Http2ConnectionHandler implements Http2FrameListener {

    static final ByteBuf RESPONSE_BYTES = unreleasableBuffer(
            copiedBuffer("Hello World", CharsetUtil.UTF_8)).asReadOnly();

    HelloWorldHttp2Handler(Http2ConnectionDecoder decoder, Http2ConnectionEncoder encoder,
                           Http2Settings initialSettings) {
        super(decoder, encoder, initialSettings);
    }

    private static Http2Headers http1HeadersToHttp2Headers(FullHttpRequest request) {
        CharSequence host = request.headers().get(HttpHeaderNames.HOST);
        Http2Headers http2Headers = new DefaultHttp2Headers()
                .method(HttpMethod.GET.asciiName())
                .path(request.uri())
                .scheme(HttpScheme.HTTP.name());
        if (host != null) {
            http2Headers.authority(host);
        }
        return http2Headers;
    }

    /**
     * Handles the cleartext HTTP upgrade event. If an upgrade occurred, sends a simple response via HTTP/2
     * on stream 1 (the stream specifically reserved for cleartext HTTP upgrade).
     */
    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        if (evt instanceof HttpServerUpgradeHandler.UpgradeEvent) {
            HttpServerUpgradeHandler.UpgradeEvent upgradeEvent =
                    (HttpServerUpgradeHandler.UpgradeEvent) evt;
            onHeadersRead(ctx, 1, http1HeadersToHttp2Headers(upgradeEvent.upgradeRequest()), 0 , true);
        }
        super.userEventTriggered(ctx, evt);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        super.exceptionCaught(ctx, cause);
        cause.printStackTrace();
        ctx.close();
    }

    /**
     * Sends a "Hello World" DATA frame to the client.
     */
    private void sendResponse(ChannelHandlerContext ctx, int streamId, ByteBuf payload) {
        // Send a frame for the response status
        Http2Headers headers = new DefaultHttp2Headers().status(OK.codeAsText());
        encoder().writeHeaders(ctx, streamId, headers, 0, false, ctx.newPromise());
        encoder().writeData(ctx, streamId, payload, 0, true, ctx.newPromise());

        // no need to call flush as channelReadComplete(...) will take care of it.
    }

    @Override
    public int onDataRead(ChannelHandlerContext ctx, int streamId, ByteBuf data, int padding, boolean endOfStream) {
        int processed = data.readableBytes() + padding;
        if (endOfStream) {
            sendResponse(ctx, streamId, data.retain());
        }
        return processed;
    }

    @Override
    public void onHeadersRead(ChannelHandlerContext ctx, int streamId,
                              Http2Headers headers, int padding, boolean endOfStream) {
        if (endOfStream) {
            ByteBuf content = ctx.alloc().buffer();
            content.writeBytes(RESPONSE_BYTES.duplicate());
            ByteBufUtil.writeAscii(content, " - via HTTP/2");
            sendResponse(ctx, streamId, content);
        }
    }

    @Override
    public void onHeadersRead(ChannelHandlerContext ctx, int streamId, Http2Headers headers, int streamDependency,
                              short weight, boolean exclusive, int padding, boolean endOfStream) {
        onHeadersRead(ctx, streamId, headers, padding, endOfStream);
    }