Curator基本操作

1 Maven导入

• 官网：Apache Curator –
• API文档：Overview (Apache Curator 5.2.1-SNAPSHOT API)

<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-framework</artifactId>
    <version>5.1.0</version>
</dependency>
<dependency>
    <groupId>org.apache.curator</groupId>
    <artifactId>curator-recipes</artifactId>
    <version>5.1.0</version>
</dependency>

2 基本操作

2.1 连接客户端

//3000为超时时间（单位：毫秒），10为最大重试次数
RetryPolicy retryPolicy = new ExponentialBackoffRetry(3000, 10);

//-------------------第一种方式------------------------
//参数1：服务端地址+端口号，参数2：会话超时时间，参数3：连接超时时间
CuratorFramework client = CuratorFrameworkFactory.newClient("192.168.170.148:2181", 
               60 * 1000, 15 * 1000, retryPolicy);

//-------------------第二种方式------------------------
CuratorFramework client = CuratorFrameworkFactory.builder()
                .connectString("192.168.170.148:2181")
                .sessionTimeoutMs(60 * 1000)
                .connectionTimeoutMs(15 * 1000)
                .retryPolicy(retryPolicy).build();

//开启连接
client.start();

2.2 创建节点

//1、基本创建：默认存储当前客户端的ip地址
String path = curatorFramework.create().forPath("/app3");
System.out.println(path);

//2、创建临时节点
String path2 = curatorFramework.create().withMode(CreateMode.EPHEMERAL).forPath("/app4");
System.out.println(path2);

//3、创建多级节点
String path3 = curatorFramework.create().creatingParentsIfNeeded().forPath("/app5/p1");
System.out.println(path3);

2.3 查询节点

//1、查询数据：get
byte[] data = curatorFramework.getData().forPath("/app1");
System.out.println(new String(data));

//2、查询子节点：ls
List<String> list = curatorFramework.getChildren().forPath("/");
System.out.println(list);

//3、查询节点状态信息：ls -s
Stat stat = new Stat();
curatorFramework.getData().storingStatIn(stat).forPath("/app1");
System.out.println(stat);

2.4 修改节点

//1、修改节点数据（基本修改）
curatorFramework.setData().forPath("/app1", "333".getBytes(StandardCharsets.UTF_8));

//2、根据版本号修改
Stat stat1 = new Stat();
curatorFramework.getData().storingStatIn(stat1).forPath("/app1");
curatorFramework.setData().withVersion(stat1.getVersion()).forPath("/app1", "itcast".getBytes(StandardCharsets.UTF_8));

2.5 删除节点

//1、删除单个节点
curatorFramework.delete().forPath("/app1");

//2、删除带有子节点的节点
curatorFramework.delete().deletingChildrenIfNeeded().forPath("/app1");

//3、必须成功地删除，删除不成功会持续重试
curatorFramework.delete().guaranteed().forPath("/app1");

//4、删除后回调
curatorFramework.delete().inBackground((curatorFramework1, curatorEvent) -> {
    System.out.println(curatorFramework1);
    System.out.println(curatorEvent);
}).forPath("/app1");

2.6 监听节点

2.6.1 监听单个节点

CuratorCache curatorCache = CuratorCache.build(client, "/test1");
curatorCache.listenable().addListener((type, childData, childData1) -> {
    System.out.println("--------------------------");
    //变化类型
    System.out.println(type);
    System.out.println("--------------------------");
    //变化前节点
    System.out.println(childData);
    System.out.println(new String(childData.getData()));
    System.out.println("--------------------------");
    //变化后节点
    System.out.println(childData1);
    System.out.println(new String(childData1.getData()));
    System.out.println("--------------------------");
});
curatorCache.start();

2.6.2 监听所有子节点

CuratorCache curatorCache = CuratorCache.build(client, "/test1");
CuratorCacheListener curatorCacheListener = CuratorCacheListener
	.builder()
	.forPathChildrenCache("/test1", client, (curatorFramework, pathChildrenCacheEvent) -> {
        System.out.println("子节点变化了~");
        //监听子节点的数据变更，并且拿到变更后的数据
        //1.获取类型
        PathChildrenCacheEvent.Type type = pathChildrenCacheEvent.getType();
        System.out.println(type);
        //2.判断类型是否是update
        if(type.equals(PathChildrenCacheEvent.Type.CHILD_UPDATED)){
            System.out.println("数据变了！！！");
            byte[] data = pathChildrenCacheEvent.getData().getData();
            System.out.println(new String(data));

        }
}).build();
curatorCache.listenable().addListener(curatorCacheListener);
curatorCache.start();

2.6.3 监听节点树

CuratorCache curatorCache = CuratorCache.build(client, "/");
CuratorCacheListener curatorCacheListener = CuratorCacheListener
    .builder()
    .forTreeCache(client, (curatorFramework, treeCacheEvent) -> {
        System.out.println("节点变化了");
        System.out.println(treeCacheEvent);
        System.out.println(new String(treeCacheEvent.getData().getData()));
    }).build();
curatorCache.listenable().addListener(curatorCacheListener);
curatorCache.start();

2.6.3 5.0以前版本

//----------------- 监听单个节点 -----------------------------------
//1. 创建NodeCache对象
final NodeCache nodeCache = new NodeCache(client,"/app1");
//2. 注册监听
nodeCache.getListenable().addListener(new NodeCacheListener() {
    @Override
    public void nodeChanged() throws Exception {
        System.out.println("节点变化了~");

        //获取修改节点后的数据
        byte[] data = nodeCache.getCurrentData().getData();
        System.out.println(new String(data));
    }
});
//3. 开启监听.如果设置为true，则开启监听是，加载缓冲数据
nodeCache.start(true);


//----------------- 监听子节点 -----------------------------------
//1.创建监听对象
PathChildrenCache pathChildrenCache = new PathChildrenCache(client,"/app2",true);
//2. 绑定监听器
pathChildrenCache.getListenable().addListener(new PathChildrenCacheListener() {
    @Override
    public void childEvent(CuratorFramework client, PathChildrenCacheEvent event)  {
        System.out.println("子节点变化了~");
        System.out.println(event);
        //监听子节点的数据变更，并且拿到变更后的数据
        //1.获取类型
        PathChildrenCacheEvent.Type type = event.getType();
        //2.判断类型是否是update
        if(type.equals(PathChildrenCacheEvent.Type.CHILD_UPDATED)){
            System.out.println("数据变了！！！");
            byte[] data = event.getData().getData();
            System.out.println(new String(data));

        }
    }
});
//3. 开启
pathChildrenCache.start();


//----------------- 监听节点树 -----------------------------------
//1. 创建监听器
TreeCache treeCache = new TreeCache(client,"/app2");
//2. 注册监听
treeCache.getListenable().addListener(new TreeCacheListener() {
    @Override
    public void childEvent(CuratorFramework client, TreeCacheEvent event) {
        System.out.println("节点变化了");
        System.out.println(event);
    }
});
//3. 开启
treeCache.start();