dubbo-router

1、引入 jar 包

     
         org.apache.curator
         curator-recipes
         4.2.0
     
     
         org.apache.dubbo
         dubbo
     

2、新建工具类 ZookeeperClients

public class ZookeeperClients {

    private final CuratorFramework client;

    private static ZookeeperClients INSTANCE;

    static {
        RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000,3);
        CuratorFramework client = CuratorFrameworkFactory.newClient("101.132.167.18:2181",retryPolicy);
        INSTANCE = new ZookeeperClients(client);
    }

    private ZookeeperClients(CuratorFramework client){
        this.client = client;
    }

    public static CuratorFramework client(){
        return INSTANCE.client;
    }
}

3、新建 ReadyRestartInstances

public class ReadyRestartInstances implements PathChildrenCacheListener {

    private static final Logger LOGGER = LoggerFactory.getLogger(ReadyRestartInstances.class);

    private static final String LISTEN_PATHS = "/lagou/dubbo/restart/instances";

    private final CuratorFramework zkClient;

    // 当节点变化时，给这个集合赋值，重启机器的信息列表
    private volatile Set restartInstance = new HashSet<>();

    private ReadyRestartInstances(CuratorFramework zkClient){
        this.zkClient = zkClient;
    }

    public static ReadyRestartInstances create(){
        final CuratorFramework zookeeperClient = ZookeeperClients.client();
        try{

            // 检查监听路径是否存在
            final Stat stat = zookeeperClient.checkExists().forPath(LISTEN_PATHS);
            // 如果监听路径不存在，则创建
            if(stat == null){
                zookeeperClient.create().creatingParentsIfNeeded().forPath(LISTEN_PATHS);
            }
        }catch (Exception e){
            e.printStackTrace();
            LOGGER.error("确保基础路径存在");
        }
        final ReadyRestartInstances instances = new ReadyRestartInstances(zookeeperClient);
        // 创建一个 NodeCache
        PathChildrenCache nodeCache = new PathChildrenCache(zookeeperClient,LISTEN_PATHS,false);
        // 给节点缓存对象加入监听
        nodeCache.getListenable().addListener(instances);
        try{
            nodeCache.start();
        }catch (Exception e){
            e.printStackTrace();
            LOGGER.error("启动监听失败");
        }
        return instances;
    }
    /** 返回应用名 和 主机拼接后的字符串 **/
    private String buildApplicationAndInstanceString(String applicationName,String host){
        return applicationName + "_" + host;
    }
    /** 增加重启实例的配置信息方法 **/
    public void addRestartingInstance(String applicationName,String host) throws Exception{
        zkClient.create().creatingParentsIfNeeded().forPath(LISTEN_PATHS + "/" + buildApplicationAndInstanceString(applicationName,host));
    }

    /** 删除重启实例的配置信息方法 **/
    public void deleteRestartingInstance(String applicationName,String host) throws Exception{
        zkClient.delete().forPath(LISTEN_PATHS + "/" + buildApplicationAndInstanceString(applicationName,host));
    }

    /** 判断节点信息是否存在于 restartInstances **/
    public boolean hasRestartingInstance(String applicationName,String host){
        return restartInstance.contains(buildApplicationAndInstanceString(applicationName,host));
    }

    @Override
    public void childEvent(CuratorFramework curatorFramework, PathChildrenCacheEvent pathChildrenCacheEvent) throws Exception {
        // 查询出监听路径下所有的目录配置信息
        final List restartingInstances = zkClient.getChildren().forPath(LISTEN_PATHS);
        // 给 restartInstances;
        if(CollectionUtils.isEmpty(restartingInstances)){
            this.restartInstance = Collections.emptySet();
        }else{
            this.restartInstance = new HashSet<>(restartingInstances);
        }
    }
}