Curator入门教程1

 简介

Curator是Netflix开源的一套ZooKeeper客户端框架. Netflix在使用ZooKeeper的过程中发现ZooKeeper自带的客户端太底层, 应用方在使用的时候需要自己处理很多事情, 于是在它的基础上包装了一下, 提供了一套更好用的客户端框架。

1、zookekeeper基本功能

     连接zookeeper,对节点进行crud、回调函数、判断节点是否存在

package bjsxt.curator.base;

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 = "192.168.0.4:2181,192.168.0.9:2181,192.168.0.6:2181";
    /** 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("修改前c2节点====="+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("修改后c2节点====="+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");
        cf.close();
    }
}

2、watcher方式一（监听当前节点发生变更）

package bjsxt.curator.watcher;

import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;

import org.apache.curator.framework.recipes.cache.NodeCache;
import org.apache.curator.framework.recipes.cache.NodeCacheListener;
import org.apache.curator.retry.ExponentialBackoffRetry;

public class CuratorWatcher1 {

    /** zookeeper地址 */
    static final String CONNECT_ADDR = "192.168.0.4:2181,192.168.0.9:2181,192.168.0.6:2181";
    /** 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)
                    .build();

        //3 建立连接
        cf.start();

        //4 建立一个cache缓存
        final NodeCache cache = new NodeCache(cf, "/super", false);
        cache.start(true);
        cache.getListenable().addListener(new NodeCacheListener() {
            /**
             * <B>方法名称：</B>nodeChanged<BR>
             * <B>概要说明：</B>触发事件为创建节点和更新节点，在删除节点的时候并不触发此操作。<BR>
             * @see org.apache.curator.framework.recipes.cache.NodeCacheListener#nodeChanged()
             */
            @Override
            public void nodeChanged() throws Exception {
                System.out.println("监听节点路径=====" + cache.getCurrentData().getPath());
                System.out.println("数据=====" + new String(cache.getCurrentData().getData()));
                System.out.println("状态=====" + cache.getCurrentData().getStat());
                System.out.println("---------------------------------------");
            }
        });

        Thread.sleep(1000);
        cf.create().forPath("/super", "123".getBytes());

        Thread.sleep(1000);
        cf.setData().forPath("/super", "456".getBytes());

        Thread.sleep(1000);
        cf.delete().forPath("/super");

        Thread.sleep(Integer.MAX_VALUE);

    }
}

3、watcher方式二（监听当前节点的子节点发生变更）

package bjsxt.curator.watcher;

import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.cache.PathChildrenCache;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheListener;
import org.apache.curator.framework.recipes.cache.PathChildrenCache.StartMode;
import org.apache.curator.retry.ExponentialBackoffRetry;

public class CuratorWatcher2 {

    /** zookeeper地址 */
    static final String CONNECT_ADDR = "192.168.0.4:2181,192.168.0.9:2181,192.168.0.6:2181";
    /** 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)
                    .build();

        //3 建立连接
        cf.start();

        //4 建立一个PathChildrenCache缓存,第三个参数为是否接受节点数据内容 如果为false则不接受
        PathChildrenCache cache = new PathChildrenCache(cf, "/super", true);
        //5 在初始化的时候就进行缓存监听
        cache.start(StartMode.POST_INITIALIZED_EVENT);
        cache.getListenable().addListener(new PathChildrenCacheListener() {
            /**
             * <B>方法名称：</B>监听子节点变更<BR>
             * <B>概要说明：</B>新建、修改、删除<BR>
             * @see org.apache.curator.framework.recipes.cache.PathChildrenCacheListener#childEvent(org.apache.curator.framework.CuratorFramework, org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent)
             */
            @Override
            public void childEvent(CuratorFramework cf, PathChildrenCacheEvent event) throws Exception {
                switch (event.getType()) {
                case CHILD_ADDED:
                    System.out.println("新增子节点 =====" + event.getData().getPath());
                    break;
                case CHILD_UPDATED:
                    System.out.println("修改子节点=====" + event.getData().getPath());
                    break;
                case CHILD_REMOVED:
                    System.out.println("删除子节点=====" + event.getData().getPath());
                    break;
                default:
                    break;
                }
            }
        });

        //创建本身节点不发生变化
        cf.create().forPath("/super", "init".getBytes());

        //添加子节点
        Thread.sleep(1000);
        cf.create().forPath("/super/c1", "c1内容".getBytes());
        Thread.sleep(1000);
        cf.create().forPath("/super/c2", "c2内容".getBytes());

        //修改子节点
        Thread.sleep(1000);
        cf.setData().forPath("/super/c1", "c1更新内容".getBytes());

        //删除子节点
        Thread.sleep(1000);
        cf.delete().forPath("/super/c2");        

        //删除本身节点
        Thread.sleep(1000);
        cf.delete().deletingChildrenIfNeeded().forPath("/super");

        Thread.sleep(Integer.MAX_VALUE);

    }
}