HttpServerExpectContinueHandler Class — netty Architecture

Source Code

codec-http/src/main/java/io/netty/handler/codec/http/HttpServerExpectContinueHandler.java lines 47–97

public class HttpServerExpectContinueHandler extends ChannelInboundHandlerAdapter {

    private static final FullHttpResponse EXPECTATION_FAILED = new DefaultFullHttpResponse(
            HTTP_1_1, HttpResponseStatus.EXPECTATION_FAILED, Unpooled.EMPTY_BUFFER);

    private static final FullHttpResponse ACCEPT = new DefaultFullHttpResponse(
            HTTP_1_1, CONTINUE, Unpooled.EMPTY_BUFFER);

    static {
        EXPECTATION_FAILED.headers().set(CONTENT_LENGTH, 0);
        ACCEPT.headers().set(CONTENT_LENGTH, 0);
    }

    /**
     * Produces a {@link HttpResponse} for {@link HttpRequest}s which define an expectation. Returns {@code null} if the
     * request should be rejected. See {@link #rejectResponse(HttpRequest)}.
     */
    protected HttpResponse acceptMessage(@SuppressWarnings("unused") HttpRequest request) {
        return ACCEPT.retainedDuplicate();
    }

    /**
     * Returns the appropriate 4XX {@link HttpResponse} for the given {@link HttpRequest}.
     */
    protected HttpResponse rejectResponse(@SuppressWarnings("unused") HttpRequest request) {
        return EXPECTATION_FAILED.retainedDuplicate();
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        if (msg instanceof HttpRequest) {
            HttpRequest req = (HttpRequest) msg;

            if (HttpUtil.is100ContinueExpected(req)) {
                HttpResponse accept = acceptMessage(req);

                if (accept == null) {
                    // the expectation failed so we refuse the request.
                    HttpResponse rejection = rejectResponse(req);
                    ReferenceCountUtil.release(msg);
                    ctx.writeAndFlush(rejection).addListener(ChannelFutureListener.CLOSE_ON_FAILURE);
                    return;
                }

                ctx.writeAndFlush(accept).addListener(ChannelFutureListener.CLOSE_ON_FAILURE);
                req.headers().remove(HttpHeaderNames.EXPECT);
            }
        }
        super.channelRead(ctx, msg);
    }
}