尚硅谷大数据技术之Zookeeper （新）第4章 Zookeeper实战（开发重点）
4.3 API应用
4.3.1 Eclipse环境搭建
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
需要在项目的src/main/resources目录下，新建一个文件，命名为“log4j.properties”，在文件中填入。
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
4.3.2 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(); } } }); } |
4.3.3 创建子节点
|
// 创建子节点 @Test public void create() throws Exception {
// 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("/atguigu", "jinlian".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); } |
4.3.4 获取子节点并监听节点变化
|
// 获取子节点 @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); } |
4.3.5 判断Znode是否存在
|
// 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"); } |
