建站教程图解,制作相册音乐相册模板,微信机器人网站开发,网站空间是指什么ZooKeeper提供了多种功能#xff0c;包括分布式锁、配置管理、服务发现、领导选举等。
下面是一些常见的ZooKeeper功能及其在Java中的应用示例代码。
分布式锁
import org.apache.zookeeper.*;
import java.io.IOException;
import java.util.concurrent.CountDownLatch;pu…ZooKeeper提供了多种功能包括分布式锁、配置管理、服务发现、领导选举等。
下面是一些常见的ZooKeeper功能及其在Java中的应用示例代码。
分布式锁
import org.apache.zookeeper.*;
import java.io.IOException;
import java.util.concurrent.CountDownLatch;public class DistributedLock implements Watcher {private static final String ZOOKEEPER_ADDRESS localhost:2181;private static final int SESSION_TIMEOUT 5000;private static final String LOCK_PATH /distributed-lock;private ZooKeeper zooKeeper;private String currentLockPath;private CountDownLatch lockSignal;public DistributedLock() throws IOException, InterruptedException, KeeperException {// 创建ZooKeeper对象建立与ZooKeeper服务器的连接zooKeeper new ZooKeeper(ZOOKEEPER_ADDRESS, SESSION_TIMEOUT, this);lockSignal new CountDownLatch(1);// 确保锁的根节点存在ensurePathExists(LOCK_PATH);}public void lock() throws KeeperException, InterruptedException {// 创建临时顺序节点作为锁节点String lockNodePath zooKeeper.create(LOCK_PATH /lock-, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);while (true) {// 获取锁节点下的所有子节点ListString children zooKeeper.getChildren(LOCK_PATH, false);Collections.sort(children);// 获取当前锁节点在所有子节点中的位置int index children.indexOf(lockNodePath.substring(LOCK_PATH.length() 1));if (index 0) {// 如果当前锁节点是第一个节点则获取到了锁this.currentLockPath lockNodePath;return;} else {// 如果当前锁节点不是第一个节点则监听前一个节点的删除事件然后等待String previousLockPath LOCK_PATH / children.get(index - 1);zooKeeper.exists(previousLockPath, true);lockSignal.await();}}}public void unlock() throws KeeperException, InterruptedException {// 删除当前锁节点zooKeeper.delete(currentLockPath, -1);currentLockPath null;}private void ensurePathExists(String path) throws KeeperException, InterruptedException {// 确保路径存在如果不存在则创建持久节点if (zooKeeper.exists(path, false) null) {zooKeeper.create(path, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);}}Overridepublic void process(WatchedEvent watchedEvent) {if (watchedEvent.getType() Event.EventType.NodeDeleted watchedEvent.getPath().equals(currentLockPath)) {// 当前锁节点被删除时唤醒等待线程lockSignal.countDown();}}
}
配置管理
import org.apache.zookeeper.*;
import java.io.IOException;
import java.util.concurrent.CountDownLatch;public class ConfigManager implements Watcher {private static final String ZOOKEEPER_ADDRESS localhost:2181;private static final int SESSION_TIMEOUT 5000;private static final String CONFIG_PATH /config;private ZooKeeper zooKeeper;private CountDownLatch configSignal;private String currentConfig;public ConfigManager() throws IOException, InterruptedException, KeeperException {// 创建ZooKeeper对象建立与ZooKeeper服务器的连接zooKeeper new ZooKeeper(ZOOKEEPER_ADDRESS, SESSION_TIMEOUT, this);configSignal new CountDownLatch(1);// 确保配置节点存在ensurePathExists(CONFIG_PATH);}public String getConfig() throws KeeperException, InterruptedException {// 获取配置节点的数据并等待配置更新byte[] data zooKeeper.getData(CONFIG_PATH, true, null);configSignal.await();return new String(data);}private void ensurePathExists(String path) throws KeeperException, InterruptedException {// 确保路径存在如果不存在则创建持久节点if (zooKeeper.exists(path, false) null) {zooKeeper.create(path, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);}}Overridepublic void process(WatchedEvent watchedEvent) {if (watchedEvent.getType() Event.EventType.NodeDataChanged watchedEvent.getPath().equals(CONFIG_PATH)) {try {// 当配置节点数据发生变化时获取最新的配置数据并唤醒等待线程byte[] data zooKeeper.getData(CONFIG_PATH, true, null);currentConfig new String(data);configSignal.countDown();} catch (KeeperException | InterruptedException e) {e.printStackTrace();}}}
}
服务发现
import org.apache.zookeeper.*;
import java.io.IOException;
import java.util.List;
import java.util.concurrent.CountDownLatch;public class ServiceDiscovery implements Watcher {private static final String ZOOKEEPER_ADDRESS localhost:2181;private static final int SESSION_TIMEOUT 5000;private static final String SERVICE_PATH /services;private ZooKeeper zooKeeper;private CountDownLatch serviceSignal;private ListString currentServices;public ServiceDiscovery() throws IOException, InterruptedException, KeeperException {// 创建ZooKeeper对象建立与ZooKeeper服务器的连接zooKeeper new ZooKeeper(ZOOKEEPER_ADDRESS, SESSION_TIMEOUT, this);serviceSignal new CountDownLatch(1);// 确保服务节点存在ensurePathExists(SERVICE_PATH);}public ListString getServices() throws KeeperException, InterruptedException {// 获取服务节点的子节点列表并等待服务更新ListString children zooKeeper.getChildren(SERVICE_PATH, true);serviceSignal.await();return currentServices;}private void ensurePathExists(String path) throws KeeperException, InterruptedException {// 确保路径存在如果不存在则创建持久节点if (zooKeeper.exists(path, false) null) {zooKeeper.create(path, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);}}Overridepublic void process(WatchedEvent watchedEvent) {if (watchedEvent.getType() Event.EventType.NodeChildrenChanged watchedEvent.getPath().equals(SERVICE_PATH)) {try {// 当服务节点的子节点发生变化时获取最新的服务列表并唤醒等待线程ListString children zooKeeper.getChildren(SERVICE_PATH, true);currentServices children;serviceSignal.countDown();} catch (KeeperException | InterruptedException e) {e.printStackTrace();}}}
}
以上是对示例代码的详细注释希望能够帮助您理解代码的功能和使用方式。
