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netty之Netty请求响应同步通信

article 2024/10/4 14:30:42

前言

实现开发RPC框架的时候，需要选择socket的通信方式。而我们知道一般情况下socket通信类似与qq聊天，发过去消息，什么时候回复都可以。但是我们RPC框架通信，从感觉上类似http调用，需要在一定时间内返回，否则就会发生超时断开。这里我们选择netty作为我们的socket框架，采用future方式进行通信。
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public class MyClientHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object obj) throws Exception {
        Response msg = (Response) obj;
        String requestId = msg.getRequestId();
        SyncWriteFuture future = (SyncWriteFuture) SyncWriteMap.syncKey.get(requestId);
        if (future != null) {
            future.setResponse(msg);
        }
    }

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

}

public class SyncWrite {

    public Response writeAndSync(final Channel channel, final Request request, final long timeout) throws Exception {

        if (channel == null) {
            throw new NullPointerException("channel");
        }
        if (request == null) {
            throw new NullPointerException("request");
        }
        if (timeout <= 0) {
            throw new IllegalArgumentException("timeout <= 0");
        }

        String requestId = UUID.randomUUID().toString();
        request.setRequestId(requestId);

        WriteFuture<Response> future = new SyncWriteFuture(request.getRequestId());
        SyncWriteMap.syncKey.put(request.getRequestId(), future);

        Response response = doWriteAndSync(channel, request, timeout, future);

        SyncWriteMap.syncKey.remove(request.getRequestId());
        return response;
    }

    private Response doWriteAndSync(final Channel channel, final Request request, final long timeout, final WriteFuture<Response> writeFuture) throws Exception {

        channel.writeAndFlush(request).addListener(new ChannelFutureListener() {
            public void operationComplete(ChannelFuture future) throws Exception {
                writeFuture.setWriteResult(future.isSuccess());
                writeFuture.setCause(future.cause());
                //失败移除
                if (!writeFuture.isWriteSuccess()) {
                    SyncWriteMap.syncKey.remove(writeFuture.requestId());
                }
            }
        });

        Response response = writeFuture.get(timeout, TimeUnit.MILLISECONDS);
        if (response == null) {
            if (writeFuture.isTimeout()) {
                throw new TimeoutException();
            } else {
                // write exception
                throw new Exception(writeFuture.cause());
            }
        }
        return response;
    }

}

public class MyServerHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object obj) {
        Request msg = (Request) obj;
        //反馈
        Response request = new Response();
        request.setRequestId(msg.getRequestId());
        request.setParam(msg.getResult() + " 请求成功，反馈结果请接受处理｛公众号：关注明哥｝。");
        ctx.writeAndFlush(request);
        //释放
        ReferenceCountUtil.release(msg);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.flush();
    }

}

public class StartClient {

    private static ChannelFuture future;

    public static void main(String[] args) {
        System.out.println("hi 微信公众号：关注明哥");
        ClientSocket client = new ClientSocket();
        new Thread(client).start();

        while (true) {
            try {
                //获取future，线程有等待处理时间
                if (null == future) {
                    future = client.getFuture();
                    Thread.sleep(500);
                    continue;
                }
                //构建发送参数
                Request request = new Request();
                request.setResult("查询｛关注明哥｝用户信息");
                SyncWrite s = new SyncWrite();
                Response response = s.writeAndSync(future.channel(), request, 1000);
                System.out.println("调用结果：" + JSON.toJSON(response));
                Thread.sleep(1000);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

}


public class StartServer {

    public static void main(String[] args) {
        new Thread(new ServerSocket()).start();
        System.out.println("server start done. {关注明哥，获取源码}");
    }

}