前言：利用netty异步事件驱动的网络通信模型，来实现rpc通信

一、大致目录结构：

二、两个端：服务端（发布），客户端（订阅消费），上代码：

1.服务端（发布）：

RPCServer：

代码：

public class RpcServer {


    private Map<String, Object> registryMap = new HashMap<>();
    private List<String> classCache = new ArrayList<>();

    // 1.实现发布；实现方式：
    // 1.1查找指定目录下的所有接口，放入一个集合中
    // 1.2遍历所有接口，放入一个map中存放接口路径及接口名称
    // 1.3发送方法相关信息


    public void publish(String providerPackage) throws Exception {

        getProviderClass(providerPackage);
        doRegister();

        NioEventLoopGroup parentGroup = new NioEventLoopGroup();
        NioEventLoopGroup childGroup = new NioEventLoopGroup();

        try {

            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(parentGroup, childGroup)
                    .option(ChannelOption.SO_BACKLOG, 1024)
                    .childOption(ChannelOption.SO_KEEPALIVE, true)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            ChannelPipeline pipeline = socketChannel.pipeline();
                            pipeline.addLast(new ObjectEncoder());
                            pipeline.addLast(new ObjectDecoder(Integer.MAX_VALUE, ClassResolvers.cacheDisabled(null)));
                            pipeline.addLast(new RpcServerHandler(registryMap));
                        }
                    });

            ChannelFuture future = serverBootstrap.bind(9999).sync();
            System.out.println("服务端监听9999端口，启动成功。。。");
            future.channel().closeFuture().sync();

        } catch (Exception e) {
            e.printStackTrace();
        } finally {

            parentGroup.shutdownGracefully();
            childGroup.shutdownGracefully();
        }
    }

    private void doRegister() throws Exception {

        if (classCache.size() > 0) {
            for (String className :classCache){

                Class<?> clazz = Class.forName(className);
                String interfaceName = clazz.getInterfaces()[0].getName();
                registryMap.put(interfaceName, clazz.newInstance());
            }
        }


    }


    /**
     * 获取当前目录下的所有接口，汇总到一个集合中
     * @param providerPackage
     */
    private void getProviderClass(String providerPackage) {

        URL resource =         this.getClass().getClassLoader().getResource(providerPackage.replaceAll("\\.", "/"));

        File file = null;
        if (resource != null) {
            file = new File(resource.getFile());
        }

        if (file != null) {
            for (File f : Objects.requireNonNull(file.listFiles())) {
                if (f.isDirectory()) {
                    getProviderClass(providerPackage + "." + f.getName());
                } else if (f.getName().endsWith(".class")) {
                    String fileName = f.getName().replace(".class", "").trim();
                    classCache.add(providerPackage + "." + fileName);
                }
            }
        }
    }


}

服务端处理器：用于处理消费端发送过来的接口数据

代码：

public class RpcServerHandler extends ChannelInboundHandlerAdapter {

    private Map<String, Object> registryMap;

    public RpcServerHandler(Map<String, Object> registryMap) {
        this.registryMap = registryMap;
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

        System.out.println("rpc-server收到客户端消息：" + msg);

        if (msg instanceof InvokeMessage) {
            InvokeMessage method = (InvokeMessage) msg;
            Object result = "rpc-server端没有该方法";

            // 判断是否存在该方法
            if (registryMap.containsKey(method.getClassName())) {
                Object provider = registryMap.get(method.getClassName());
                result = provider.getClass()
                        .getMethod(method.getMethodName(), method.getParamTypes())
                        .invoke(provider, method.getParamValues());
            }
            // 把方法返回结果，发给订阅者
            ctx.channel().writeAndFlush(result);
            ctx.close();
        }

    }


    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

接口的实现类：这里的接口是客户端的接口Api

代码：

public class SsenServiceApiImpl implements SsenServiceApi {

    @Override
    public String hellRpc(String name) {
        return name + "实现类方法";
    }
}

2.客户端：（订阅消费）

这里采用JDK原生的基于接口的动态代理f发

public class RpcProxy {


    // JDK基于接口的动态代理，用于创建代理对象
    public static <T> T create(Class<?> clazz) {
        return (T) Proxy.newProxyInstance(clazz.getClassLoader(),
                new Class[]{clazz},
                new InvocationHandler() {
                    @Override
                    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                        if (Object.class.equals(method.getDeclaringClass())) {
                            return method.invoke(proxy, method, args);
                        }

                        // 通过netty将接口信息发送给提供者，获取指定方法
                        return RpcInvoke(clazz, method, args);
                    }
                });
    }

    private static Object RpcInvoke(Class<?> clazz, Method method, Object[] args) {
        NioEventLoopGroup eventGroup = new NioEventLoopGroup();

        RpcClientHandler rpcClientHandler = new RpcClientHandler();

        try {

            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(eventGroup)
                    .channel(NioSocketChannel.class)
                    .option(ChannelOption.TCP_NODELAY, true)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            ChannelPipeline pipeline = socketChannel.pipeline();
                            pipeline.addLast(new ObjectEncoder());
                            pipeline.addLast(new ObjectDecoder(Integer.MAX_VALUE,
                                    ClassResolvers.cacheDisabled(null)));
                            pipeline.addLast(rpcClientHandler);
                        }
                    });

            // 绑定指定服务地址
            ChannelFuture future = bootstrap.connect("localhost", 9999).sync();

            // 指定接口信息发送给提供者
            InvokeMessage invokeMessage = new InvokeMessage();
            invokeMessage.setClassName(clazz.getName());
            invokeMessage.setMethodName(method.getName());
            invokeMessage.setParamTypes(method.getParameterTypes());
            invokeMessage.setParamValues(args);
            future.channel().writeAndFlush(invokeMessage).sync();

            future.channel().closeFuture().sync();

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            eventGroup.shutdownGracefully();
        }
        return rpcClientHandler.getResult();
    }

}