zookeepercurator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：
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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]新闻名称：zookeepercurator基本使用
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