Netty做HTTP server

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一、简介

1、用netty作为通信框架

2、集成spring mvc来处理http请求

二、Server端

1、server接收端
正常启动netty server即可。netty的启动会阻塞后续的执行，所以单独建一个SingleThreadExecutor来执行start，这样不会阻塞主线程，也可以直接对线程池进行控制。

netty接受到请求后转发给HttpServerHandler处理

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private void startBootstrap() throws Exception {
    EventLoopGroup bossGroup = new NioEventLoopGroup();
    EventLoopGroup workerGroup = new NioEventLoopGroup();
    try {
        ServerBootstrap bootstrap = new ServerBootstrap();
        bootstrap.group(bossGroup, workerGroup);
        bootstrap.channel(NioServerSocketChannel.class);
        bootstrap.childHandler(new ServletChannelInitializer());
        bootstrap.option(ChannelOption.SO_BACKLOG, 128);
        bootstrap.childOption(ChannelOption.SO_KEEPALIVE, true);

        String[] addressArray = StringUtil.split(httpAddress, ":");
        String ip = addressArray[0];
        int port = Integer.parseInt(addressArray[1]);
        ChannelFuture future = bootstrap.bind(ip, port).sync();
        LOGGER.info("HTTP srver started on ip:" + ip + ", port :" + port);
        future.channel().closeFuture().sync();
    } finally {
        workerGroup.shutdownGracefully();
        bossGroup.shutdownGracefully();
    }
}
@Override
public void initChannel(SocketChannel ch) {
     ch.pipeline().addLast("decoder", new HttpRequestDecoder());
     ch.pipeline().addLast("aggregator", new HttpObjectAggregator(65536));
     ch.pipeline().addLast("encoder", new HttpResponseEncoder());
     ch.pipeline().addLast("chunkedWriter", new ChunkedWriteHandler());
     ch.pipeline().addLast("httpServerHandler", new HttpServerHandler(dispatcherServlet));
}

HttpServerHandler收到FullHttpRequest后，转换成spring的MockHttpServletRequest(必须是ServletRequest，才可以做后续的解析和转发)

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MockHttpServletRequest servletRequest = createServletRequest(request);
MockHttpServletResponse servletResponse = new MockHttpServletResponse();

this.servlet.service(servletRequest, servletResponse);  //自定义servlet处理request和response

HttpResponseStatus status = HttpResponseStatus.valueOf(servletResponse.getStatus());
DefaultFullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, status,
        Unpooled.wrappedBuffer(servletResponse.getContentAsByteArray()));

for (String name : servletResponse.getHeaderNames()) {
    for (Object value : servletResponse.getHeaderValues(name)) {
        response.headers().add(name, value);
    }
}
ChannelFuture writeFuture = ctx.write(response);
writeFuture.addListener(ChannelFutureListener.CLOSE);

Spring配置好扫描路径，在Controller的类和方法中加入SpringMVC的相应注解，

通过this.servlet.service(servletRequest, servletResponse)将request转发至自定义的dispatcher，处理request后，便能正常转发至Controller中执行。