Zookeeper API for JAVA实战与应用

1.创建一个Maven工程

2.添加pom文件

    <dependencies>

        <dependency>

            <groupId>junit</groupId>

            <artifactId>junit</artifactId>

            <version>RELEASE</version>

        </dependency>

        <dependency>

            <groupId>org.apache.logging.log4j</groupId>

            <artifactId>log4j-core</artifactId>

            <version>2.8.2</version>

        </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.zookeeper/zookeeper -->

        <dependency>

            <groupId>org.apache.zookeeper</groupId>

            <artifactId>zookeeper</artifactId>

            <version>3.4.10</version>

        </dependency>

    </dependencies>

3.拷贝log4j.properties文件到项目根目录

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

4.创建ZooKeeper客户端

private static String connectString = "hadoop102:2181,hadoop103:2181,hadoop104:2181";
    private static int sessionTimeout = 2000;
    private ZooKeeper zkClient = null;

    @Before
    public void init() throws Exception {

    zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            @Override
            public void process(WatchedEvent event) {
                // 收到事件通知后的回调函数（用户的业务逻辑）
                System.out.println(event.getType() + "--" + event.getPath());

                // 再次启动监听
                try {
                    zkClient.getChildren("/", true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

5.创建子节点

@Test
    public void create() throws Exception {
        // 数据的增删改查
        // 参数1：要创建的节点的路径； 参数2：节点数据 ； 参数3：节点权限 ；参数4：节点的类型
        String nodeCreated = zkClient.create("/eclipse", "hello zk".getBytes(), Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);
    }

6.获取子节点并监听

@Test
    public void getChildren() throws Exception {
        List<String> children = zkClient.getChildren("/", true);
        for (String child : children) {
            System.out.println(child);
        }
        // 延时阻塞
        Thread.sleep(Long.MAX_VALUE);
    }

7.判断znode是否存在

@Test
    public void exist() throws Exception {
        Stat stat = zkClient.exists("/eclipse", false);

        System.out.println(stat == null ? "not exist" : "exist");
    }