聊聊Gateway集成Netty服務

作者：知了一笑 2023-02-28 08:55:33

開發前端

Netty是一個異步的，事件驅動的網絡應用框架，用以快速開發高可靠、高性能的網絡應用程序。

一、Netty簡介

Netty是一個異步的，事件驅動的網絡應用框架，用以快速開發高可靠、高性能的網絡應用程序。

傳輸服務：提供網絡傳輸能力的管理；

協議支持：支持常見的數據傳輸協議；

核心模塊：包括可擴展事件模型、通用的通信API、零拷貝字節緩沖；

二、Netty入門案例

1、服務端啟動

配置Netty服務器端程序，引導相關核心組件的加載；

public class NettyServer {

    public static void main(String[] args) {

        // EventLoop組，處理事件和IO
        EventLoopGroup parentGroup = new NioEventLoopGroup();
        EventLoopGroup childGroup = new NioEventLoopGroup();

        try {

            // 服務端啟動引導類
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(parentGroup, childGroup)
                    .channel(NioServerSocketChannel.class).childHandler(new ChannelInit());

            // 異步IO的結果
            ChannelFuture channelFuture = serverBootstrap.bind(8082).sync();
            channelFuture.channel().closeFuture().sync();

        } catch (Exception e){
            e.printStackTrace();
        } finally {
            parentGroup.shutdownGracefully();
            childGroup.shutdownGracefully();
        }
    }
}

2、通道初始化

ChannelInitializer特殊的通道處理器，提供一種簡單的方法，對注冊到EventLoop的通道進行初始化；比如此處設置的編碼解碼器，自定義處理器；

public class ChannelInit extends ChannelInitializer<SocketChannel> {

    @Override
    protected void initChannel(SocketChannel socketChannel) {

        // 獲取管道
        ChannelPipeline pipeline = socketChannel.pipeline();

        // Http編碼、解碼器
        pipeline.addLast("DefHttpServerCodec",new HttpServerCodec());

        // 添加自定義的handler
        pipeline.addLast("DefHttpHandler", new DefHandler());
    }
}

3、自定義處理器

處理對服務器端發起的訪問，通常包括請求解析，具體的邏輯執行，請求響應等過程；

public class DefHandler extends SimpleChannelInboundHandler<HttpObject> {

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, HttpObject message) throws Exception {

        if(message instanceof HttpRequest) {
            // 請求解析
            HttpRequest httpRequest = (HttpRequest) message;
            String uri = httpRequest.uri();
            String method = httpRequest.method().name();
            log.info("【HttpRequest-URI:"+uri+"】");
            log.info("【HttpRequest-method:"+method+"】");

            Iterator<Map.Entry<String,String>> iterator = httpRequest.headers().iteratorAsString();
            while (iterator.hasNext()){
                Map.Entry<String,String> entry = iterator.next();
                log.info("【Header-Key:"+entry.getKey()+";Header-Value:"+entry.getValue()+"】");
            }

            // 響應構建
            ByteBuf content = Unpooled.copiedBuffer("Netty服務", CharsetUtil.UTF_8);
            FullHttpResponse response = new DefaultFullHttpResponse
                                        (HttpVersion.HTTP_1_1, HttpResponseStatus.OK, content);
            response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/plain;charset=utf-8");
            response.headers().set(HttpHeaderNames.CONTENT_LENGTH, content.readableBytes());
            ctx.writeAndFlush(response);
        }
    }
}

4、測試請求

上面入門案例中，簡單的配置了一個Netty服務器端，啟動之后在瀏覽器中模擬訪問即可；

http://127.0.0.1:8082/?id=1&name=Spring

三、Gateway集成

1、依賴層級

項目中Gateway網關依賴的版本為2.2.5.RELEASE?，發現Netty依賴的版本為4.1.45.Final，是當下比較主流的版本；

<!-- 1、項目工程依賴 -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-gateway</artifactId>
    <version>2.2.5.RELEASE</version>
</dependency>

<!-- 2、starter-gateway依賴 -->
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-webflux</artifactId>
  <version>2.3.2.RELEASE</version>
</dependency>

<!-- 3、starter-webflux依賴 -->
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-reactor-netty</artifactId>
  <version>2.3.2.RELEASE</version>
</dependency>

2、自動化配置

在Gateway網關的自動化配置配置類中，提供了Netty配置的管理；

@AutoConfigureBefore({ HttpHandlerAutoConfiguration.class,WebFluxAutoConfiguration.class })
@ConditionalOnClass(DispatcherHandler.class)
public class GatewayAutoConfiguration {

    @Configuration(proxyBeanMethods = false)
    @ConditionalOnClass(HttpClient.class)
    protected static class NettyConfiguration {

        @Bean
        @ConditionalOnProperty(name = "spring.cloud.gateway.httpserver.wiretap")
        public NettyWebServerFactoryCustomizer nettyServerWiretapCustomizer(
                Environment environment, ServerProperties serverProperties) {
            return new NettyWebServerFactoryCustomizer(environment, serverProperties) {
                @Override
                public void customize(NettyReactiveWebServerFactory factory) {
                    factory.addServerCustomizers(httpServer -> httpServer.wiretap(true));
                    super.customize(factory);
                }
            };
        }
    }
}

四、配置加載

1、基礎配置

在工程的配置文件中，簡單做一些基礎性的設置；

server:
  port: 8081                  # 端口號
  netty:                      # Netty組件
    connection-timeout: 3000  # 連接超時

2、屬性配置類

在ServerProperties類中，并沒有提供很多顯式的Netty配置參數，更多信息需要參考工廠類；

@ConfigurationProperties(prefix = "server", ignoreUnknownFields = true)
public class ServerProperties {
    private Integer port;
    public static class Netty {
        private Duration connectionTimeout;
    }
}

3、配置加載分析

基于配置的屬性，定制化管理Netty服務的信息；

public class NettyWebServerFactoryCustomizer
        implements WebServerFactoryCustomizer<NettyReactiveWebServerFactory>{
    private final Environment environment;
    private final ServerProperties serverProperties;
    @Override
    public void customize(NettyReactiveWebServerFactory factory) {
        PropertyMapper propertyMapper = PropertyMapper.get().alwaysApplyingWhenNonNull();
        ServerProperties.Netty nettyProperties = this.serverProperties.getNetty();
        propertyMapper.from(nettyProperties::getConnectionTimeout).whenNonNull()
                .to((connectionTimeout) -> customizeConnectionTimeout(factory, connectionTimeout));
    }
}

NettyReactiveWeb服務工廠，基于上述入門案例，創建WebServer時，部分參數信息出自LoopResources接口；

public class NettyReactiveWebServerFactory extends AbstractReactiveWebServerFactory {

    private ReactorResourceFactory resourceFactory;

    @Override
    public WebServer getWebServer(HttpHandler httpHandler) {
        HttpServer httpServer = createHttpServer();
        ReactorHttpHandlerAdapter handlerAdapter = new ReactorHttpHandlerAdapter(httpHandler);
        NettyWebServer webServer = new NettyWebServer(httpServer, handlerAdapter, this.lifecycleTimeout);
        webServer.setRouteProviders(this.routeProviders);
        return webServer;
    }
    
    private HttpServer createHttpServer() {
  HttpServer server = HttpServer.create();
  if (this.resourceFactory != null) {
         LoopResources resources = this.resourceFactory.getLoopResources();
         server = server.tcpConfiguration(
           (tcpServer) -> tcpServer.runOn(resources).addressSupplier(this::getListenAddress));
        }
        return applyCustomizers(server);
 }
 
}

五、周期管理方法

1、控制類

Gateway項目中，Netty服務核心控制類，通過NettyReactiveWebServerFactory工廠類創建，對Netty生命周期的管理提供了一層包裝；

public class NettyWebServer implements WebServer {

    private final HttpServer httpServer;
    private final ReactorHttpHandlerAdapter handlerAdapter;

    /**
     * 啟動方法
     */
    @Override
    public void start() throws WebServerException {
        if (this.disposableServer == null) {
            this.disposableServer = startHttpServer();
            // 控制臺日志
            logger.info("Netty started on port(s): " + getPort());
            startDaemonAwaitThread(this.disposableServer);
        }
    }
    private DisposableServer startHttpServer() {
        HttpServer server = this.httpServer;
        if (this.routeProviders.isEmpty()) {
            server = server.handle(this.handlerAdapter);
        }
        return server.bindNow();
    }

    /**
     * 停止方法
     */
    @Override
    public void stop() throws WebServerException {
        if (this.disposableServer != null) {
            // 釋放資源
            if (this.lifecycleTimeout != null) {
                this.disposableServer.disposeNow(this.lifecycleTimeout);
            }
            else {
                this.disposableServer.disposeNow();
            }
            // 對象銷毀
            this.disposableServer = null;
        }
    }
}

2、管理類

Netty組件中抽象管理類，以安全的方式構建Http服務；

public abstract class HttpServer {

    public static HttpServer create() {
        return HttpServerBind.INSTANCE;
    }

    public final DisposableServer bindNow() {
        return bindNow(Duration.ofSeconds(45));
    }

    public final HttpServer handle(BiFunction<? super HttpServerRequest, ? super
            HttpServerResponse, ? extends Publisher<Void>> handler) {
        return new HttpServerHandle(this, handler);
    }
}

六、參考源碼

編程文檔：
https://gitee.com/cicadasmile/butte-java-note

應用倉庫：
https://gitee.com/cicadasmile/butte-flyer-parent

責任編輯：武曉燕來源：知了一笑