zookeeper curator 基本使用

下面，我们将通过一个简单的示例演示curator最基本的crud功能：

maven依赖：

          org.apache.zookeeper      zookeeper      3.4.12              org.apache.curator      curator-recipes      2.12.0                    junit          junit          4.12          test        

测试类：

package per.ym.zookeeper;import java.util.List;import org.apache.curator.RetryPolicy;import org.apache.curator.framework.CuratorFramework;import org.apache.curator.framework.CuratorFrameworkFactory;import org.apache.curator.retry.BoundedExponentialBackoffRetry;import org.apache.curator.retry.ExponentialBackoffRetry;import org.apache.curator.retry.RetryForever;import org.apache.curator.retry.RetryNTimes;import org.apache.curator.retry.RetryOneTime;import org.apache.curator.retry.RetryUntilElapsed;import org.apache.zookeeper.data.Stat;import org.junit.After;import org.junit.Before;import org.junit.Test;public class CuratorBasicAPI {    private CuratorFramework client;    private String connectString = "192.168.61.131:2184";    private int sessionTimeoutMs = 60000;    private int connectionTimeoutMs = 60000;    private String path = "/test";    private String rootPath = "/";    private byte[] data = "data".getBytes();    private byte[] newData = "newData".getBytes();    private int baseSleepTimeMs = 1000;    private int maxRetries = 3;    @Before    public void connect() {        //baseSleepTimeMs：基础睡眠时间；maxRetries：最大重试次数；maxSleepMs：两次重试之间最大睡眠时间        //其睡眠时间计算公式为：sleepMs = baseSleepTimeMs * Math.max(1, random.nextInt(1 << (retryCount + 1)));        RetryPolicy retryPolicy1 = new ExponentialBackoffRetry(baseSleepTimeMs, maxRetries);        //ExponentialBackoffRetry的子类，重写了父类的getSleepTimeMs方法        //其睡眠时间计算公式为：Math.min(maxSleepTimeMs, super.getSleepTimeMs(retryCount, elapsedTimeMs));        RetryPolicy retryPolicy2 = new BoundedExponentialBackoffRetry(baseSleepTimeMs, 50000, maxRetries);        //最大重试3次，每次相隔时间为5000毫秒        RetryPolicy retryPolicy3 = new RetryNTimes(3, 5000);        //只重试一次，RetryNTimes的子类，就是将次数指定为1        RetryPolicy retryPolicy4 = new RetryOneTime(3000);        //一直重试，重试间隔为3000毫秒        RetryPolicy retryPolicy5 = new RetryForever(3000);        //最大重试时间为20000毫秒，若超过就不重试了，每次间隔3000毫秒        RetryPolicy retryPolicy6 = new RetryUntilElapsed(20000, 3000);        //client = CuratorFrameworkFactory.newClient(connectString, sessionTimeoutMs, connectionTimeoutMs, retryPolicy);        //流式        client = CuratorFrameworkFactory.builder()                        .connectString(connectString) //服务器列表，格式host1:port1,host2:port2,…                        .sessionTimeoutMs(sessionTimeoutMs) //会话超时时间，单位毫秒，默认60000ms                        .connectionTimeoutMs(connectionTimeoutMs) //连接创建超时时间，单位毫秒，默认60000ms                        .retryPolicy(retryPolicy1)                        .build();        //启动        client.start();    }    @Test    public void showBasicAPI() throws Exception {        exist();        create();        exist();        getData();        setData();        getData();        getChildren();        delete();        getChildren();    }    @After    public void close() {        //关闭连接        client.close();    }    private void create() throws Exception {        //创建一个节点        //client.create().forPath(path);        //创建一个节点附带数据        client.create().forPath(path, data);        System.out.println("创建节点：" + path);        //创建一个临时节点，默认不指定是持久的，另外还有持久带序列和临时带序列PERSISTENT_SEQUENTIAL、EPHEMERAL_SEQUENTIAL        //client.create().withMode(CreateMode.EPHEMERAL).forPath(path);        //如果没有父目录则一起创建        //client.create().creatingParentsIfNeeded().forPath(path);        //后天模式，还可以传入自定义CallBack和线程池        //client.create().inBackground().forPath(path);        //带权限的        //List aclList = new ArrayList();        //acls.add(new ACL(Perms.ALL, new Id("digest", "520:1314")));        //client.create().withACL(aclList).forPath(path);        //当然你也这可这样        //client.create().creatingParentsIfNeeded().withMode(CreateMode.EPHEMERAL).withACL(aclList).inBackground().forPath(path, data);    }    private void exist() throws Exception {        Stat stat = client.checkExists().forPath(path);        if (stat == null) {            System.out.println("节点" + path + "不存在。");        } else {            System.out.println("节点" + path + "存在。");        }    }    private void getData() throws Exception {        byte[] byteData = client.getData().forPath(path);        //client.getData().inBackground().forPath(path);        //Stat stat = new Stat();        //client.getData().storingStatIn(stat).forPath("path");        System.out.println("节点" + path + "的数据为：" + new String(byteData));    }    private void setData() throws Exception {        client.setData().forPath(path, newData);        System.out.println("设置节点" + path + "数据为：" + new String(newData));        //client.setData().inBackground().forPath(path, newData);        //指定版本，若版本错误将抛出异常bad version        //client.setData().withVersion(520).forPath(path,newData);    }    private void delete() throws Exception {        client.delete().forPath(path);        System.out.println("删除节点：" + path);        //client.delete().withVersion(1314).forPath(path);        //只要会话有效将一直尝试删除，直到删除成功        //client.delete().guaranteed().forPath(path);        //同        //client.delete().deletingChildrenIfNeeded().forPath(path);        //client.delete().inBackground().forPath(path);        //client.delete().guaranteed().deletingChildrenIfNeeded().withVersion(1314).inBackground().forPath(path);    }    private void getChildren() throws Exception {        List names = client.getChildren().forPath(rootPath);        System.out.println("根目录下有节点：" + names);        //client.getChildren().inBackground().forPath(rootPath);    }}

运行结果：节点/test不存在。创建节点：/test节点/test存在。节点/test的数据为：data设置节点/test数据为：newData节点/test的数据为：newData根目录下有节点：[zookeeper, test]删除节点：/test根目录下有节点：[zookeeper]