亚洲精品m在线观看,丁香伊人,国产精品怕怕怕视频免费

一. 背景

最近的一個項目：我們的系統(tǒng)接收到上游系統(tǒng)的派單任務(wù)后，會推送到指定的門店的相關(guān)設(shè)備，并進(jìn)行相應(yīng)的業(yè)務(wù)處理。

二. Netty 的使用

在接收到派單任務(wù)之后，通過 Netty 推送到指定門店相關(guān)的設(shè)備。在我們的系統(tǒng)中 Netty 實現(xiàn)了消息推送、長連接以及心跳機(jī)制。

Netty + ZooKeeper 實現(xiàn)簡單的服務(wù)注冊與發(fā)現(xiàn)

2.1 Netty Server 端:

每個 Netty 服務(wù)端通過 ConcurrentHashMap 保存了客戶端的 clientId 以及它連接的 SocketChannel。

服務(wù)器端向客戶端發(fā)送消息時，只要獲取 clientId 對應(yīng)的 SocketChannel，往 SocketChannel 里寫入相應(yīng)的 message 即可。

EventLoopGroup boss = new NioEventLoopGroup(1);
  EventLoopGroup worker = new NioEventLoopGroup();
  ServerBootstrap bootstrap = new ServerBootstrap();
  bootstrap.group(boss, worker)
    .channel(NioServerSocketChannel.class)
    .option(ChannelOption.SO_BACKLOG, 128)
    .option(ChannelOption.TCP_NODELAY, true)
    .childOption(ChannelOption.SO_KEEPALIVE, true)
    .childHandler(new ChannelInitializer() {
     @Override
     protected void initChannel(Channel channel) throws Exception {
      ChannelPipeline p = channel.pipeline();
      p.addLast(new MessageEncoder());
      p.addLast(new MessageDecoder());
      p.addLast(new PushServerHandler());
     }
    });
  ChannelFuture future = bootstrap.bind(host,port).sync();
  if (future.isSuccess()) {
   logger.info("server start...");
  }

2.2 Netty Client 端:

客戶端用于接收服務(wù)端的消息，隨即進(jìn)行業(yè)務(wù)處理。客戶端還有心跳機(jī)制，它通過 IdleEvent 事件定時向服務(wù)端放送 Ping 消息以此來檢測 SocketChannel 是否中斷。

public PushClientBootstrap(String host, int port) throws InterruptedException {
  this.host = host;
  this.port = port;
  start(host,port);
 }
 private void start(String host, int port) throws InterruptedException {
  bootstrap = new Bootstrap();
  bootstrap.channel(NioSocketChannel.class)
    .option(ChannelOption.SO_KEEPALIVE, true)
    .group(workGroup)
    .remoteAddress(host, port)
    .handler(new ChannelInitializer(){
     @Override
     protected void initChannel(Channel channel) throws Exception {
      ChannelPipeline p = channel.pipeline();
      p.addLast(new IdleStateHandler(20, 10, 0)); // IdleStateHandler 用于檢測心跳
      p.addLast(new MessageDecoder());
      p.addLast(new MessageEncoder());
      p.addLast(new PushClientHandler());
     }
    });
  doConnect(port, host);
 }
 /**
  * 建立連接，并且可以實現(xiàn)自動重連.
  * @param port port.
  * @param host host.
  * @throws InterruptedException InterruptedException.
  */
 private void doConnect(int port, String host) throws InterruptedException {
  if (socketChannel != null && socketChannel.isActive()) {
   return;
  }
  final int portConnect = port;
  final String hostConnect = host;
  ChannelFuture future = bootstrap.connect(host, port);
  future.addListener(new ChannelFutureListener() {
   @Override
   public void operationComplete(ChannelFuture futureListener) throws Exception {
    if (futureListener.isSuccess()) {
     socketChannel = (SocketChannel) futureListener.channel();
     logger.info("Connect to server successfully!");
    } else {
     logger.info("Failed to connect to server, try connect after 10s");
     futureListener.channel().eventLoop().schedule(new Runnable() {
      @Override
      public void run() {
       try {
        doConnect(portConnect, hostConnect);
       } catch (InterruptedException e) {
        e.printStackTrace();
       }
      }
     }, 10, TimeUnit.SECONDS);
    }
   }
  }).sync();
 }

三. 借助 ZooKeeper 實現(xiàn)簡單的服務(wù)注冊與發(fā)現(xiàn)

3.1 服務(wù)注冊

服務(wù)注冊本質(zhì)上是為了解耦服務(wù)提供者和服務(wù)消費者。服務(wù)注冊是一個高可用強(qiáng)一致性的服務(wù)發(fā)現(xiàn)存儲倉庫，主要用來存儲服務(wù)的api和地址對應(yīng)關(guān)系。為了高可用，服務(wù)注冊中心一般為一個集群，并且能夠保證分布式一致性。目前常用的有 ZooKeeper、Etcd 等等。

在我們項目中采用了 ZooKeeper 實現(xiàn)服務(wù)注冊。

public class ServiceRegistry {
 private static final Logger logger = LoggerFactory.getLogger(ServiceRegistry.class);
 private CountDownLatch latch = new CountDownLatch(1);
 private String registryAddress;
 public ServiceRegistry(String registryAddress) {
  this.registryAddress = registryAddress;
 }
 public void register(String data) {
  if (data != null) {
   ZooKeeper zk = connectServer();
   if (zk != null) {
    createNode(zk, data);
   }
  }
 }
 /**
  * 連接 zookeeper 服務(wù)器
  * @return
  */
 private ZooKeeper connectServer() {
  ZooKeeper zk = null;
  try {
   zk = new ZooKeeper(registryAddress, Constants.ZK_SESSION_TIMEOUT, new Watcher() {
    @Override
    public void process(WatchedEvent event) {
     if (event.getState() == Event.KeeperState.SyncConnected) {
      latch.countDown();
     }
    }
   });
   latch.await();
  } catch (IOException | InterruptedException e) {
   logger.error("", e);
  }
  return zk;
 }
 /**
  * 創(chuàng)建節(jié)點
  * @param zk
  * @param data
  */
 private void createNode(ZooKeeper zk, String data) {
  try {
   byte[] bytes = data.getBytes();
   String path = zk.create(Constants.ZK_DATA_PATH, bytes, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
   logger.debug("create zookeeper node ({} => {})", path, data);
  } catch (KeeperException | InterruptedException e) {
   logger.error("", e);
  }
 }
}

有了服務(wù)注冊，在 Netty 服務(wù)端啟動之后，將 Netty 服務(wù)端的 ip 和 port 注冊到 ZooKeeper。

EventLoopGroup boss = new NioEventLoopGroup(1);
  EventLoopGroup worker = new NioEventLoopGroup();
  ServerBootstrap bootstrap = new ServerBootstrap();
  bootstrap.group(boss, worker)
    .channel(NioServerSocketChannel.class)
    .option(ChannelOption.SO_BACKLOG, 128)
    .option(ChannelOption.TCP_NODELAY, true)
    .childOption(ChannelOption.SO_KEEPALIVE, true)
    .childHandler(new ChannelInitializer() {
     @Override
     protected void initChannel(Channel channel) throws Exception {
      ChannelPipeline p = channel.pipeline();
      p.addLast(new MessageEncoder());
      p.addLast(new MessageDecoder());
      p.addLast(new PushServerHandler());
     }
    });
  ChannelFuture future = bootstrap.bind(host,port).sync();
  if (future.isSuccess()) {
   logger.info("server start...");
  }
  if (serviceRegistry != null) {
   serviceRegistry.register(host + ":" + port);
  }

3.2 服務(wù)發(fā)現(xiàn)

這里我們采用的是客戶端的服務(wù)發(fā)現(xiàn)，即服務(wù)發(fā)現(xiàn)機(jī)制由客戶端實現(xiàn)。

客戶端在和服務(wù)端建立連接之前，通過查詢注冊中心的方式來獲取服務(wù)端的地址。如果存在有多個 Netty 服務(wù)端的話，可以做服務(wù)的負(fù)載均衡。在我們的項目中只采用了簡單的隨機(jī)法進(jìn)行負(fù)載。

public class ServiceDiscovery {
 private static final Logger logger = LoggerFactory.getLogger(ServiceDiscovery.class);
 private CountDownLatch latch = new CountDownLatch(1);
 private volatile List<String> serviceAddressList = new ArrayList<>();
 private String registryAddress; // 注冊中心的地址
 public ServiceDiscovery(String registryAddress) {
  this.registryAddress = registryAddress;
  ZooKeeper zk = connectServer();
  if (zk != null) {
   watchNode(zk);
  }
 }
 /**
  * 通過服務(wù)發(fā)現(xiàn)，獲取服務(wù)提供方的地址
  * @return
  */
 public String discover() {
  String data = null;
  int size = serviceAddressList.size();
  if (size > 0) {
   if (size == 1) { //只有一個服務(wù)提供方
    data = serviceAddressList.get(0);
    logger.info("unique service address : {}", data);
   } else {   //使用隨機(jī)分配法。簡單的負(fù)載均衡法
    data = serviceAddressList.get(ThreadLocalRandom.current().nextInt(size));
    logger.info("choose an address : {}", data);
   }
  }
  return data;
 }
 /**
  * 連接 zookeeper
  * @return
  */
 private ZooKeeper connectServer() {
  ZooKeeper zk = null;
  try {
   zk = new ZooKeeper(registryAddress, Constants.ZK_SESSION_TIMEOUT, new Watcher() {
    @Override
    public void process(WatchedEvent event) {
     if (event.getState() == Watcher.Event.KeeperState.SyncConnected) {
      latch.countDown();
     }
    }
   });
   latch.await();
  } catch (IOException | InterruptedException e) {
   logger.error("", e);
  }
  return zk;
 }
 /**
  * 獲取服務(wù)地址列表
  * @param zk
  */
 private void watchNode(final ZooKeeper zk) {
  try {
   //獲取子節(jié)點列表
   List<String> nodeList = zk.getChildren(Constants.ZK_REGISTRY_PATH, new Watcher() {
    @Override
    public void process(WatchedEvent event) {
     if (event.getType() == Event.EventType.NodeChildrenChanged) {
      //發(fā)生子節(jié)點變化時再次調(diào)用此方法更新服務(wù)地址
      watchNode(zk);
     }
    }
   });
   List<String> dataList = new ArrayList<>();
   for (String node : nodeList) {
    byte[] bytes = zk.getData(Constants.ZK_REGISTRY_PATH + "/" + node, false, null);
    dataList.add(new String(bytes));
   }
   logger.debug("node data: {}", dataList);
   this.serviceAddressList = dataList;
  } catch (KeeperException | InterruptedException e) {
   logger.error("", e);
  }
 }
}

Netty 客戶端啟動之后，通過服務(wù)發(fā)現(xiàn)獲取 Netty 服務(wù)端的 ip 和 port。

/**
  * 支持通過服務(wù)發(fā)現(xiàn)來獲取 Socket 服務(wù)端的 host、port
  * @param discoveryAddress
  * @throws InterruptedException
  */
 public PushClientBootstrap(String discoveryAddress) throws InterruptedException {

  serviceDiscovery = new ServiceDiscovery(discoveryAddress);
  serverAddress = serviceDiscovery.discover();

  if (serverAddress!=null) {
   String[] array = serverAddress.split(":");
   if (array!=null && array.length==2) {

    String host = array[0];
    int port = Integer.parseInt(array[1]);

    start(host,port);
   }
  }
 }

四. 總結(jié)

服務(wù)注冊和發(fā)現(xiàn)一直是分布式的核心組件。本文介紹了借助 ZooKeeper 做注冊中心，如何實現(xiàn)一個簡單的服務(wù)注冊和發(fā)現(xiàn)。其實，注冊中心的選擇有很多，例如 Etcd、Eureka 等等。選擇符合我們業(yè)務(wù)需求的才是最重要的。

以上所述是小編給大家介紹的Netty + ZooKeeper 實現(xiàn)簡單的服務(wù)注冊與發(fā)現(xiàn),希望對大家有所幫助，如果大家有任何疑問請給我留言，小編會及時回復(fù)大家的。在此也非常感謝大家對服務(wù)器之家網(wǎng)站的支持！
如果你覺得本文對你有幫助，歡迎轉(zhuǎn)載，煩請注明出處，謝謝！