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1   /*
2    * Copyright 2016 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License, version 2.0 (the
5    * "License"); you may not use this file except in compliance with the License. You may obtain a
6    * copy of the License at:
7    *
8    * http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software distributed under the License
11   * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
12   * or implied. See the License for the specific language governing permissions and limitations under
13   * the License.
14   */
15  
16  package io.netty.example.http2.helloworld.multiplex.server;
17  
18  import static io.netty.buffer.Unpooled.copiedBuffer;
19  import static io.netty.buffer.Unpooled.unreleasableBuffer;
20  import static io.netty.handler.codec.http.HttpResponseStatus.OK;
21  import io.netty.buffer.ByteBuf;
22  import io.netty.buffer.ByteBufUtil;
23  import io.netty.channel.ChannelDuplexHandler;
24  import io.netty.channel.ChannelHandler.Sharable;
25  import io.netty.channel.ChannelHandlerContext;
26  import io.netty.handler.codec.http2.DefaultHttp2DataFrame;
27  import io.netty.handler.codec.http2.DefaultHttp2Headers;
28  import io.netty.handler.codec.http2.DefaultHttp2HeadersFrame;
29  import io.netty.handler.codec.http2.Http2DataFrame;
30  import io.netty.handler.codec.http2.Http2Headers;
31  import io.netty.handler.codec.http2.Http2HeadersFrame;
32  import io.netty.util.CharsetUtil;
33  
34  /**
35   * A simple handler that responds with the message "Hello World!".
36   *
37   * <p>This example is making use of the "multiplexing" http2 API, where streams are mapped to child
38   * Channels. This API is very experimental and incomplete.
39   */
40  @Sharable
41  public class HelloWorldHttp2Handler extends ChannelDuplexHandler {
42  
43      static final ByteBuf RESPONSE_BYTES = unreleasableBuffer(copiedBuffer("Hello World", CharsetUtil.UTF_8));
44  
45      @Override
46      public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
47          super.exceptionCaught(ctx, cause);
48          cause.printStackTrace();
49          ctx.close();
50      }
51  
52      @Override
53      public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
54          if (msg instanceof Http2HeadersFrame) {
55              onHeadersRead(ctx, (Http2HeadersFrame) msg);
56          } else if (msg instanceof Http2DataFrame) {
57              onDataRead(ctx, (Http2DataFrame) msg);
58          } else {
59              super.channelRead(ctx, msg);
60          }
61      }
62  
63      @Override
64      public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
65          ctx.flush();
66      }
67  
68      /**
69       * If receive a frame with end-of-stream set, send a pre-canned response.
70       */
71      private static void onDataRead(ChannelHandlerContext ctx, Http2DataFrame data) throws Exception {
72          if (data.isEndStream()) {
73              sendResponse(ctx, data.content());
74          } else {
75              // We do not send back the response to the remote-peer, so we need to release it.
76              data.release();
77          }
78      }
79  
80      /**
81       * If receive a frame with end-of-stream set, send a pre-canned response.
82       */
83      private static void onHeadersRead(ChannelHandlerContext ctx, Http2HeadersFrame headers)
84              throws Exception {
85          if (headers.isEndStream()) {
86              ByteBuf content = ctx.alloc().buffer();
87              content.writeBytes(RESPONSE_BYTES.duplicate());
88              ByteBufUtil.writeAscii(content, " - via HTTP/2");
89              sendResponse(ctx, content);
90          }
91      }
92  
93      /**
94       * Sends a "Hello World" DATA frame to the client.
95       */
96      private static void sendResponse(ChannelHandlerContext ctx, ByteBuf payload) {
97          // Send a frame for the response status
98          Http2Headers headers = new DefaultHttp2Headers().status(OK.codeAsText());
99          ctx.write(new DefaultHttp2HeadersFrame(headers));
100         ctx.write(new DefaultHttp2DataFrame(payload, true));
101     }
102 }