ZooKeeper【客户端的API操作、写数据流程】

<dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <version>2.18.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.zookeeper</groupId>
            <artifactId>zookeeper</artifactId>
            <version>3.5.7</version>
        </dependency>
    </dependencies>

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

 @Before
    public void init() throws IOException {
        zkClient = new ZooKeeper(connectString, sessionTimeOut, new Watcher() {
            //process方法可以为空 在这里设置的监听并不是监听一次就关闭而是一直监听            
            @Override
            public void process(WatchedEvent watchedEvent) {
                System.out.println("----------init------------");
                List<String> children = null;
                try {
                    children = zkClient.getChildren("/sanguo", true);
                } catch (KeeperException | InterruptedException e) {
                    e.printStackTrace();
                }
                for (String child : children) {
                    System.out.println(child);
                }
            }
        });
    }

@Test
    public void create() throws InterruptedException, KeeperException {
        //创建节点并返回节点路径/sanguo/wuguo
        String Znode = zkClient.create("/sanguo/wuguo", "liubei".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
        System.out.println("Znode : "+Znode);
    }

 @Test
    public void getChildren() throws InterruptedException, KeeperException {
        System.out.println("--------------------");
        /**设置watcher为true之后就会自动执行init方法中watcher的重写的process方法
        * 如果process方法为空，则这里只会监听一次就关闭监听
        **/
        List<String> children = zkClient.getChildren("/sanguo", true);
        /**这个for循环只会被执行一次 真正的监听在初始化ZooKeeper对象中重写Wather的process方法里
        *一旦监听的节点有变化，就会从process方法输出监听到的变化结果
        **/    
        for (String child : children) {
            System.out.println(child);
        }
        //延时程序 作用就是让客户端一直开启 以方便返回监听到的变化结果
        Thread.sleep(Long.MAX_VALUE);
    }

@Test
    public void exits() throws InterruptedException, KeeperException {
        //返回节点状态 参数1是节点 参数2是是否开启监听
        Stat stat = zkClient.exists("/sanguo", false);
        System.out.println(stat==null?"not exist":"exit");
    }