(原) 2.3 Curator使用

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Curator使用

1、jar包引入，演示版本为2.6.0，非maven项目，可以下载jar包导入到项目中

       <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-framework</artifactId>
            <version>2.6.0</version>
        </dependency>

        <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-recipes</artifactId>
            <version>2.6.0</version>
        </dependency> 

2、RetryPolicy：重试机制

• ExponentialBackoffRetry：每次重试会增加重试时间baseSleepTimeMs
  • ExponentialBackoffRetry(int baseSleepTimeMs, int maxRetries)
  • ExponentialBackoffRetry(int baseSleepTimeMs, int maxRetries, int maxSleepMs)
    • baseSleepTimeMs：基本重试时间差
    • maxRetries：最大重试次数
    • maxSleepMs：最大重试时间
• RetryNTimes
  
  • RetryNTimes(int n, int sleepMsBetweenRetries)
    
    • n:重试次数
    • sleepMsBetweenRetries：每次重试间隔时间
• RetryUntilElapsed
  • RetryUntilElapsed(int maxElapsedTimeMs, int sleepMsBetweenRetries)
    
    • maxElapsedTimeMs：最大重试时间
    • sleepMsBetweenRetries：每次重试间隔时间
• BoundedExponentialBackoffRetry、RetryOneTime、SleepingRetry

3、创建Zookeeper连接

• 传统方式

　  示例：CuratorFramework curatorFramework = CuratorFrameworkFactory.newClient("192.168.117.128:2181",5000,5000,retryPolicy);

　  API：　　

newClient(java.lang.String connectString, org.apache.curator.RetryPolicy retryPolicy)

newClient(java.lang.String connectString, int sessionTimeoutMs, int connectionTimeoutMs, org.apache.curator.RetryPolicy retryPolicy)

• • connectString:Zookeeper服务器地址
  • retryPolicy：自定义重试机制
  • sessionTimeoutMs:session超时时间
  • connectionTimeoutMs：连接超时时间
• 链式方式　

curatorFramework = CuratorFrameworkFactory.builder()
                                .connectString("192.168.117.128:2181")
                                //.authorization() 设置访问权限 设置方法同原生API
                                .sessionTimeoutMs(5000).connectionTimeoutMs(5000)
                                .retryPolicy(retryPolicy).build();

• 代码示例

    public void createSession() {
        //RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000,3);//基本重试间隔时间，重试次数(每次重试时间加长)
        //RetryPolicy retryPolicy = new RetryNTimes(5,1000);//重试次数，重试间隔时间
        RetryPolicy retryPolicy = new RetryUntilElapsed(5000,1000);//重试时间，重试间隔时间
        //curatorFramework = CuratorFrameworkFactory.newClient("192.168.117.128:2181",5000,5000,retryPolicy);
        curatorFramework = CuratorFrameworkFactory.builder()
                                .connectString("192.168.117.128:2181")
                                //.authorization() 设置访问权限 设置方法同原生API
                                .sessionTimeoutMs(5000).connectionTimeoutMs(5000)
                                .retryPolicy(retryPolicy).build();
        curatorFramework.start();
    }

4、创建节点

public void createNode() throws Exception {
        createSession();
        String path = curatorFramework.create()
                .creatingParentsIfNeeded()//如果父节点没有自动创建
                //.withACL()设置权限  权限创建同原生API
                .withMode(CreateMode.PERSISTENT)//节点类型
                .forPath("/note_curator/02", "02".getBytes());
        System.out.println("path:"+path);
    }

节点类型、权限设置详见2.1Zookeeper原生API使用

5、节点删除

  public void del() throws Exception {
        createSession();
        curatorFramework.delete()
                .guaranteed()//保证机制，出错后后台删除 直到删除成功
                .deletingChildrenIfNeeded()//删除当前节点下的所有节点，再删除自身
                .forPath("/note_curator");
    }

6、获取子节点

public void getChildren() throws Exception {
        createSession();
        List<String> children = curatorFramework.getChildren().forPath("/note_curator");
        System.out.println(children);

    }

7、获取节点信息

public void getData() throws Exception {
        createSession();
        Stat stat = new Stat();
        byte[] u = curatorFramework.getData().storingStatIn(stat).forPath("/note_curator");
        System.out.println(new String(u));
        System.out.println(stat);
    }

8、设置节点信息

public void setData() throws Exception {
        createSession();
        curatorFramework.setData()
                //.withVersion(1) 设置版本号 乐观锁概念
                .forPath("/note_curator/01", "shengke0815".getBytes());
    }

9、是否存在节点

public void exists() throws Exception {
        createSession();
        Stat s = curatorFramework.checkExists().forPath("/note_curator");
        System.out.println(s);
    }

10、设置节点信息回调

 ExecutorService executorService = Executors.newFixedThreadPool(5);//线程池
    @Test
    public void setDataAsync() throws Exception {
        createSession();
        curatorFramework.setData().inBackground(new BackgroundCallback() {//设置节点信息时回调方法
            @Override
            public void processResult(CuratorFramework curatorFramework, CuratorEvent curatorEvent) throws Exception {

                System.out.println(curatorFramework.getZookeeperClient());
                System.out.println(curatorEvent.getResultCode());
                System.out.println(curatorEvent.getPath());
                System.out.println(curatorEvent.getContext());
            }
        },"shangxiawen",executorService).forPath("/note_curator","sksujer0815".getBytes());
        Thread.sleep(Integer.MAX_VALUE);
    }

API:

inBackground(org.apache.curator.framework.api.BackgroundCallback backgroundCallback, java.lang.Object o, java.util.concurrent.Executor executor);

• • backgroundCallback：自定义BackgroundCallback

  •   o：上下文信息，回调方法中curatorEvent.getContext()可获取此信息
  •   executor：线程池

11、监听节点改变事件

public void nodeListen() throws Exception {
        createSession();
        final NodeCache cache = new NodeCache(curatorFramework,"/note_curator");
        cache.start();
        cache.getListenable().addListener(new NodeCacheListener() {
            @Override
            public void nodeChanged() throws Exception {
                System.out.println(new String(cache.getCurrentData().getData()));
                System.out.println(cache.getCurrentData().getPath());
            }
        });

        Thread.sleep(Integer.MAX_VALUE);

    }

12、监听子节点列表改变事件

public void nodeClildrenListen() throws Exception {
        createSession();
        final PathChildrenCache cache = new PathChildrenCache(curatorFramework,"/note_curator",true);
        cache.start();
        cache.getListenable().addListener(new PathChildrenCacheListener() {
            @Override
            public void childEvent(CuratorFramework curatorFramework, PathChildrenCacheEvent pathChildrenCacheEvent) throws Exception {
                switch (pathChildrenCacheEvent.getType()){
                    case CHILD_ADDED:
                        System.out.println("add children");
                        System.out.println(new String(pathChildrenCacheEvent.getData().getData()));
                        System.out.println(new String(pathChildrenCacheEvent.getData().getPath()));
                        break;
                    case CHILD_REMOVED:
                        System.out.println("remove children");
                        System.out.println(new String(pathChildrenCacheEvent.getData().getData()));
                        System.out.println(new String(pathChildrenCacheEvent.getData().getPath()));
                        break;
                    case CHILD_UPDATED:
                        System.out.println("update children");
                        System.out.println(new String(pathChildrenCacheEvent.getData().getData()));
                        System.out.println(new String(pathChildrenCacheEvent.getData().getPath()));
                        break;
                }
            }
        });

        Thread.sleep(Integer.MAX_VALUE);

    }

下一节：3.1 Zookeeper应用 - Master选举