Zookeeper java api 主要有以下几个:
方法名称 | 描述 |
---|---|
String create(final String path, byte data[], List acl, CreateMode createMode) |
创建一个znode节点, 参数: 路径、 znode内容,ACL(访问控制列表)、 znode创建类型 |
void delete(final String path, int version) |
删除一个znode节点, 参数: 路径、版本号;如果版本号与znode的版本号不一致,将无法删除,是一种乐观加锁机制;如果将版本号设置为-1,不会去检测版本,直接删除; |
Stat exists(final String path, Watcher watcher) |
判断某个znode节点是否存在 参数: 路径、Watcher(监视器);当这个znode节点被改变时,将会触发当前Watcher |
Stat exists(String path, boolean watch) |
判断某个znode节点是否存在 参数: 路径、并设置是否监控这个目录节点,这里的 watcher 是在创建 ZooKeeper 实例时指定的 watcher |
Stat setData(final String path, byte data[], int version) |
设置某个znode上的数据 参数: 路径、数据、版本号;如果为-1,跳过版本检查 |
byte[] getData(final String path, Watcher watcher, Stat stat) |
获取某个znode上的数据 参数: 路径、监视器、数据版本等信息 |
List getChildren(final String path, Watcher watcher) |
获取某个节点下的所有子节点 参数: 路径、监视器;该方法有多个重载 |
package com.test.protobuf;import org.apache.zookeeper.*;import java.io.IOException;
import java.util.concurrent.CountDownLatch;/**
* Created by szekinwin on 2017/7/7.
*/
public class ZookeeperDemo { //zookeeper连接地址
private static final String CONNECT_ADDR="172.31.19.222:2181,172.31.19.223:2181,172.31.19.234:2181";
//超时时间
private static final int SESSION_TIMEOUT=2000;
//等待zookeeper连接成功,程序继续往下执行(zookeeper连接是异步连接)
private static final CountDownLatch countDownLatch = new CountDownLatch(1); public static void main (String [] args){
try {
ZooKeeper zooKeeper = new ZooKeeper(CONNECT_ADDR, SESSION_TIMEOUT, new Watcher() {
public void process(WatchedEvent event) {
Event.KeeperState state = event.getState();
Event.EventType type = event.getType();
if(Event.KeeperState.SyncConnected==state){
if(Event.EventType.None==type){
countDownLatch.countDown();
System.out.println("Zookeeper connect successfully!");
}
}
}
});
try {
countDownLatch.await();
try {
//创建节点 节点类型为PERSISTENT 永久型 EPHEMERAL临时节点,客户端session超时这类节点就会被自动删除
zooKeeper.create("/testRoot","testRoot".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
//创建子节点 zookeeper java api 不支持递归创建节点
zooKeeper.create("/testRoot/children","children".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
//获取节点值
byte [] msg=zooKeeper.getData("/testRoot/children",false,null);
System.out.println(new String(msg));
//修改节点值
zooKeeper.setData("/testRoot/children","testRoot Children".getBytes(),-1);
byte [] msg2=zooKeeper.getData("/testRoot/children",false,null);
System.out.println(new String(msg2));
//判断节点是否存在
System.out.println(zooKeeper.exists("/testRoot/children",false));
//删除节点
zooKeeper.delete("/testRoot/children",-1);
zooKeeper.close();
} catch (KeeperException e) {
e.printStackTrace();
}
} catch (InterruptedException e) {
e.printStackTrace();
}
} catch (IOException e) {
e.printStackTrace();
}
}}