import io.netty.handler.codec.http.HttpServerUpgradeHandler; //导入依赖的package包/类
private void configureHttp1WithUpgrade(ChannelHandlerContext ctx) {
    final ChannelPipeline p = ctx.pipeline();
    final HttpServerCodec http1codec = new HttpServerCodec(
            config.defaultMaxHttp1InitialLineLength(),
            config.defaultMaxHttp1HeaderSize(),
            config.defaultMaxHttp1ChunkSize());

    String baseName = name;
    baseName = addAfter(p, baseName, http1codec);
    baseName = addAfter(p, baseName, new HttpServerUpgradeHandler(
            http1codec,
            protocol -> {
                if (!AsciiString.contentEquals(Http2CodecUtil.HTTP_UPGRADE_PROTOCOL_NAME, protocol)) {
                    return null;
                }

                return new Http2ServerUpgradeCodec(
                        newHttp2ConnectionHandler(p));
            },
            UPGRADE_REQUEST_MAX_LENGTH));

    addAfter(p, baseName, new Http1RequestDecoder(config, ctx.channel(), SCHEME_HTTP));
}
 

import io.netty.handler.codec.http.HttpServerUpgradeHandler; //导入依赖的package包/类
@Override
public void userEventTriggered(final ChannelHandlerContext ctx, final Object evt)
    throws Exception {
  // Idle timeout
  if (evt instanceof IdleStateEvent) {
    log.debug("idle timeout: {}", ctx);
    ctx.close();
  } else if (evt instanceof HttpServerUpgradeHandler.UpgradeEvent) {
    // Write an HTTP/2 response to the upgrade request
    FullHttpRequest req = ((HttpServerUpgradeHandler.UpgradeEvent) evt).upgradeRequest();
    req.headers().set(STREAM_ID, req.headers().get(STREAM_ID, "1"));
    channelRead0(ctx, req);
  } else {
    super.userEventTriggered(ctx, evt);
  }
}
 

import io.netty.handler.codec.http.HttpServerUpgradeHandler; //导入依赖的package包/类
/**
 * 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) {
        // Write an HTTP/2 response to the upgrade request
        Http2Headers headers =
                new DefaultHttp2Headers().status(OK.codeAsText())
                .set(new AsciiString(UPGRADE_RESPONSE_HEADER), new AsciiString("true"));
        encoder().writeHeaders(ctx, 1, headers, 0, true, ctx.newPromise());
    }
    super.userEventTriggered(ctx, evt);
}
 

import io.netty.handler.codec.http.HttpServerUpgradeHandler; //导入依赖的package包/类
/**
 * Configure the pipeline for a cleartext upgrade from HTTP to HTTP/2.
 */
private static void configureClearText(SocketChannel ch) {
    HttpServerCodec sourceCodec = new HttpServerCodec();
    HelloWorldHttp2Handler http2Handler = new HelloWorldHttp2Handler();
    HttpServerUpgradeHandler.UpgradeCodec upgradeCodec = new Http2ServerUpgradeCodec(http2Handler);
    HttpServerUpgradeHandler upgradeHandler = new HttpServerUpgradeHandler(sourceCodec, Collections.singletonList(upgradeCodec), 65536);

    ch.pipeline().addLast(sourceCodec);
    ch.pipeline().addLast(upgradeHandler);
    ch.pipeline().addLast(new UserEventLogger());
}
 

import io.netty.handler.codec.http.HttpServerUpgradeHandler; //导入依赖的package包/类
/**
 * This method 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).
 *
 * @param ctx Channel context
 * @param evt Event
 * @throws Exception Throws when user event trigger has an error
 */
@Override
public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
    if (evt instanceof HttpServerUpgradeHandler.UpgradeEvent) {
        // Write an HTTP/2 response to the upgrade request
        Http2Headers headers =
                new DefaultHttp2Headers().status(OK.codeAsText())
                        .set(new AsciiString(Constants.UPGRADE_RESPONSE_HEADER), new AsciiString("true"));
        encoder().writeHeaders(ctx, 1, headers, 0, true, ctx.newPromise());
    }
    super.userEventTriggered(ctx, evt);
}
 

import io.netty.handler.codec.http.HttpServerUpgradeHandler; //导入依赖的package包/类
private void h2cOrHttp1(final ChannelHandlerContext ctx) {
  ChannelPipeline p = ctx.pipeline();
  HttpServerCodec http1codec = http1Codec();

  String baseName = name;
  baseName = addAfter(p, baseName, "codec", http1codec);
  baseName = addAfter(p, baseName, "h2upgrade",
      new HttpServerUpgradeHandler(http1codec, protocol -> {
        if (!AsciiString.contentEquals(Http2CodecUtil.HTTP_UPGRADE_PROTOCOL_NAME, protocol)) {
          return null;
        }
        return new Http2ServerUpgradeCodec(newHttp2ConnectionHandler(p));
      }, maxContentLength));
}