java操作zookeeper

文档

1. linux安装java -centos安装java -linux配置java环境变量
2. zookeeper单机安装
3. zookeeper集群安装
4. zookeeper客户端命令行操作、节点类型及监听器
5. zookeeper集群写数据原理
6. java操作zookeeper

依赖信息

<dependency><groupId>junit</groupId><artifactId>junit</artifactId><scope>test</scope>
</dependency>
<dependency><groupId>org.apache.logging.log4j</groupId><artifactId>log4j-core</artifactId><version>2.8.2</version>
</dependency>
<dependency><groupId>org.apache.zookeeper</groupId><artifactId>zookeeper</artifactId><version>3.5.7</version>
</dependency>

log4j配置文件

在resources下创建log4j.properties文件

log4j.rootLogger=INFO, stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d   %p  [%c]    -   %m%n
log4j.appender.logfile=org.apache.log4j.FileAppender
log4j.appender.logfile.File=target/spring.log
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d   %p  [%c]    -   %m%n

java操作zookeeper参考代码

• 包括连接zookeeper、创建节点、获取子节点列表、判断节点是否存在、监听等方法
• 注释中包含注意事项

package xin.yangshuai.zookeeper01.client;import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;import java.io.IOException;
import java.util.List;public class ZkClient {private ZooKeeper zkClient;// 注意：逗号左右不能有空格private String connectString = "192.168.145.132:2181,192.168.145.133:2181,192.168.145.134:2181";// 2000毫秒private int sessionTimeout = 2000;/*** 连接zookeeper** @throws IOException*/public void init() throws IOException {zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {@Overridepublic void process(WatchedEvent watchedEvent) {// 初始化时，会执行一次System.out.println(watchedEvent.getPath() + "-------------");try {// 注册一次，监听一次，如果想持续监听，可重新注册// getChildren()方法设置了监听，所以每次调用将重新注册监听getChildren();} catch (KeeperException | InterruptedException e) {e.printStackTrace();}}});}/*** 创建一个节点** @throws KeeperException* @throws InterruptedException*/public void create() throws KeeperException, InterruptedException {String node = zkClient.create("/client", "create-test".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);System.out.println("Created " + node);}/*** 获取子节点** @throws KeeperException* @throws InterruptedException*/public void getChildren() throws KeeperException, InterruptedException {// 参数watch设置为true，表示使用zkClient创建时的Watcher，并监听当前节点的子节点的增删变化List<String> children = zkClient.getChildren("/", true);for (String child : children) {System.out.println("children " + child);}}/*** 判断节点是否存在** @throws KeeperException* @throws InterruptedException*/public void exist() throws KeeperException, InterruptedException {Stat stat = zkClient.exists("/client", false);System.out.println(stat == null ? "not exist" : "exist");stat = zkClient.exists("/client1", false);System.out.println(stat == null ? "not exist" : "exist");}public static void main(String[] args) throws IOException, KeeperException, InterruptedException {ZkClient zkClient = new ZkClient();zkClient.init();zkClient.create();// getChildren()方法不用手动调用，zookeeper客户端初始化时，会调用监听器的process方法，可在该方法中调用getChildren()方法// zkClient.getChildren();zkClient.exist();// 保持运行状态，来观察监听器的动作Thread.sleep(Long.MAX_VALUE);// 可在命令行增删节点 / 的子节点，来触发监听器动作}
}

java中的zookeeper节点类型

持久无序号节点：CreateMode.PERSISTENT
持久有序号节点：CreateMode.PERSISTENT_SEQUENTIAL
临时无序号节点：CreateMode.EPHEMERAL
临时有序号节点：CreateMode.EPHEMERAL_SEQUENTIAL