public class IdMaker {

    private ZkClient client = null;
    private final String server;
    // zookeeper顺序节点的父节点
    private final String root;
    // 顺序节点的名称
    private final String nodeName;
    // 标识当前服务是否正在运行
    private volatile boolean running = false;
    private ExecutorService cleanExector = null;
    
    public enum RemoveMethod{
        NONE,IMMEDIATELY,DELAY
        
    }
    
    public IdMaker(String zkServer,String root,String nodeName){
        
        this.root = root;
        this.server = zkServer;
        this.nodeName = nodeName;
        
    }

    // 启动服务
    public void start() throws Exception {
        
        if (running)
            throw new Exception("server has stated...");
        running = true;
        
        init();
        
    }
    
    // 停止服务
    public void stop() throws Exception {
        
        if (!running)
            throw new Exception("server has stopped...");
        running = false;
        
        freeResource();
        
    }
    
    // 初始化服务资源
    private void init(){
        
        client = new ZkClient(server,5000,5000,new BytesPushThroughSerializer());
        cleanExector = Executors.newFixedThreadPool(10);
        try{
            client.createPersistent(root,true);
        }catch (ZkNodeExistsException e){
            //ignore;
        }
        
    }

    // 释放服务器资源
    private void freeResource(){

        // 释放线程池
        cleanExector.shutdown();
        try{
            cleanExector.awaitTermination(2, TimeUnit.SECONDS);
        }catch(InterruptedException e){
            e.printStackTrace();
        }finally{
            cleanExector = null;
        }
    
        if (client!=null){
            client.close();
            client=null;
            
        }
    }

    // 检测当前服务是否正在运行
    private void checkRunning() throws Exception {
        if (!running)
            throw new Exception("请先调用start");
        
    }

    // 从顺序节点名中提取我们要的ID值
    private String ExtractId(String str){
        int index = str.lastIndexOf(nodeName);
        if (index >= 0){
            index+=nodeName.length();
            return index <= str.length()?str.substring(index):"";
        }
        return str;
        
    }

    // 生成ID
    public String generateId(RemoveMethod removeMethod) throws Exception{
        checkRunning();

        // 构造顺序节点的完整路径
        final String fullNodePath = root.concat("/").concat(nodeName);
        // 创建持久化顺序节点
        final String ourPath = client.createPersistentSequential(fullNodePath, null);

        // 避免zookeeper的顺序节点暴增，直接删除掉刚创建的顺序节点
        if (removeMethod.equals(RemoveMethod.IMMEDIATELY)){ // 立即删除
            client.delete(ourPath);
        }else if (removeMethod.equals(RemoveMethod.DELAY)){ // 延迟删除
            cleanExector.execute(new Runnable() { // 用线程池执行删除，让generateId()方法尽快返回
                public void run() {
                    client.delete(ourPath);
                }
            });
            
        }
        //node-0000000000, node-0000000001
        return ExtractId(ourPath);
    }

}
public class TestIdMaker {

    public static void main(String[] args) throws Exception {
        
        IdMaker idMaker = new IdMaker("192.168.1.105:2181",
                "/NameService/IdGen", "ID");
        idMaker.start();

        try {
            for (int i = 0; i < 10; i++) {
                String id = idMaker.generateId(RemoveMethod.DELAY);
                System.out.println(id);
            }
        } finally {
            idMaker.stop();

        }
    }

}