Curator框架的使用

Curator框架使用链式编程风格，易读性更强，使用工厂方法创建连接对象。

1.使用CuratorFrameworkFactory的两个静态工厂方法（参数不同）来实现

参数1：connectString，连接信息

参数2：RetryPolicy，重试连接策略，有四种实现

　　ExponentialBackoffRetry、RetryNTimes、RetryOneTimes、RetryUntilElapsed

参数3：sessionTimeoutMs会话超时时间，默认为60s

参数4：connectionTimeoutMs连接超时时间，默认为15s

注意：对于retryPolicy策略通过一个接口来让用户自定义实现

import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.api.BackgroundCallback;
import org.apache.curator.framework.api.CuratorEvent;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.ZooKeeper.States;
import org.apache.zookeeper.data.Stat;

public class CuratorBase {
    
    /** zookeeper地址 */
    static final String CONNECT_ADDR = "192.168.1.171:2181,192.168.1.172:2181,192.168.1.173:2181";
    /** session超时时间 */
    static final int SESSION_OUTTIME = 5000;//ms 
    
    public static void main(String[] args) throws Exception {
        
        //1 重试策略：初试时间为1s 重试10次
        RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 10);
        //2 通过工厂创建连接
        CuratorFramework cf = CuratorFrameworkFactory.builder()
                    .connectString(CONNECT_ADDR)
                    .sessionTimeoutMs(SESSION_OUTTIME)
                    .retryPolicy(retryPolicy)
//                    .namespace("super")
                    .build();
        //3 开启连接
        cf.start();
        
//        System.out.println(States.CONNECTED);
//        System.out.println(cf.getState());
        
        // 新加、删除
        /**
        //4 建立节点 指定节点类型（不加withMode默认为持久类型节点）、路径、数据内容
        cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath("/super/c1","c1内容".getBytes());
        //5 删除节点
        cf.delete().guaranteed().deletingChildrenIfNeeded().forPath("/super");
        */
        
        // 读取、修改
        /**
        //创建节点
//        cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath("/super/c1","c1内容".getBytes());
//        cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath("/super/c2","c2内容".getBytes());
        //读取节点
//        String ret1 = new String(cf.getData().forPath("/super/c2"));
//        System.out.println(ret1);
        //修改节点
//        cf.setData().forPath("/super/c2", "修改c2内容".getBytes());
//        String ret2 = new String(cf.getData().forPath("/super/c2"));
//        System.out.println(ret2);    
        */
        
        // 绑定回调函数
        /**
        ExecutorService pool = Executors.newCachedThreadPool();
        cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT)
        .inBackground(new BackgroundCallback() {
            @Override
            public void processResult(CuratorFramework cf, CuratorEvent ce) throws Exception {
                System.out.println("code:" + ce.getResultCode());
                System.out.println("type:" + ce.getType());
                System.out.println("线程为:" + Thread.currentThread().getName());
            }
        }, pool)
        .forPath("/super/c3","c3内容".getBytes());
        Thread.sleep(Integer.MAX_VALUE);
        */
        
        
        // 读取子节点getChildren方法 和 判断节点是否存在checkExists方法
        /**
        List<String> list = cf.getChildren().forPath("/super");
        for(String p : list){
            System.out.println(p);
        }
        
        Stat stat = cf.checkExists().forPath("/super/c3");
        System.out.println(stat);
        
        Thread.sleep(2000);
        cf.delete().guaranteed().deletingChildrenIfNeeded().forPath("/super");
        */
        
        
        //cf.delete().guaranteed().deletingChildrenIfNeeded().forPath("/super");
        
    }
}