Create Zookeeper（五）.md

Author: MoRan1607

Zookeeper/Zookeeper（五）.md

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+Zookeeper实战
+---  
+### 1、IDEA环境搭建   
+1）创建一个Maven Module  
+2）添加pom文件  
+```xml
+<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>
+		<dependency>
+			<groupId>org.apache.zookeeper</groupId>
+			<artifactId>zookeeper</artifactId>
+			<version>3.5.7</version>
+		</dependency>
+</dependencies>
+```  
+3）拷贝log4j.properties文件到项目根目录   
+&emsp; 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。
+```xml
+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
+```
+### 2、初始化ZooKeeper客户端  
+```java
+public class Zookeeper {
+
+    private String connectString;
+    private int sessionTimeout;
+private ZooKeeper zkClient;
+
+    @Before   //获取客户端对象
+public void init() throws IOException {
+
+        connectString = "hadoop102:2181,hadoop103:2181,hadoop104:2181";
+        int sessionTimeout = 10000;
+        
+       //参数解读 1集群连接字符串  2连接超时时间 单位:毫秒  3当前客户端默认的监控器
+        zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
+            @Override
+            public void process(WatchedEvent event) {
+            }
+        });
+    }
+
+    @After //关闭客户端对象
+    public void close() throws InterruptedException {
+        zkClient.close();
+    }
+}
+```  
+### 3、获取子节点列表,不监听  
+```java
+@Test
+public void ls() throws IOException, KeeperException, InterruptedException {
+    //用客户端对象做各种操作
+    List<String> children = zkClient.getChildren("/", false);
+    System.out.println(children);
+}
+```  
+### 4、获取子节点列表,并监听  
+```java
+@Test
+public void lsAndWatch() throws KeeperException, InterruptedException {
+    List<String> children = zkClient.getChildren("/atguigu", new Watcher() {
+        @Override
+        public void process(WatchedEvent event) {
+            System.out.println(event);
+        }
+    });
+System.out.println(children);
+
+    //因为设置了监听,所以当前线程不能结束
+    Thread.sleep(Long.MAX_VALUE);
+}
+```   
+### 5、创建子节点  
+```java
+@Test
+public void create() throws KeeperException, InterruptedException {
+//参数解读 1节点路径  2节点存储的数据  
+//3节点的权限(使用Ids选个OPEN即可) 4节点类型 短暂 持久 短暂带序号 持久带序号
+     String path = zkClient.create("/atguigu", "shanguigu".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
+
+    //创建临时节点
+//String path = zkClient.create("/atguigu2", "shanguigu".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
+
+System.out.println(path);
+
+    //创建临时节点的话,需要线程阻塞
+    //Thread.sleep(10000);
+}
+```   
+### 6、判断Znode是否存在     
+```java
+@Test
+public void exist() throws Exception {
+
+	Stat stat = zkClient.exists("/atguigu", false);
+
+	System.out.println(stat == null ? "not exist" : "exist");
+}
+```   
+### 7、获取子节点存储的数据,不监听    
+```java
+@Test
+public void get() throws KeeperException, InterruptedException {
+    //判断节点是否存在
+    Stat stat = zkClient.exists("/atguigu", false);
+    if (stat == null) {
+        System.out.println("节点不存在...");
+        return;
+    }
+
+    byte[] data = zkClient.getData("/atguigu", false, stat);
+    System.out.println(new String(data));
+}
+```
+### 8、获取子节点存储的数据,并监听    
+```java
+@Test
+public void getAndWatch() throws KeeperException, InterruptedException {
+    //判断节点是否存在
+    Stat stat = zkClient.exists("/atguigu", false);
+    if (stat == null) {
+        System.out.println("节点不存在...");
+        return;
+    }
+
+    byte[] data = zkClient.getData("/atguigu", new Watcher() {
+        @Override
+        public void process(WatchedEvent event) {
+            System.out.println(event);
+        }
+    }, stat);
+    System.out.println(new String(data));
+    //线程阻塞
+    Thread.sleep(Long.MAX_VALUE);
+}
+```   
+### 9、设置节点的值   
+```java
+@Test
+public void set() throws KeeperException, InterruptedException {
+    //判断节点是否存在
+    Stat stat = zkClient.exists("/atguigu", false);
+    if (stat == null) {
+        System.out.println("节点不存在...");
+        return;
+    }
+    //参数解读 1节点路径 2节点的值 3版本号
+    zkClient.setData("/atguigu", "sgg".getBytes(), stat.getVersion());
+}
+```   
+### 10、删除空节点    
+```java
+@Test
+public void delete() throws KeeperException, InterruptedException {
+    //判断节点是否存在
+    Stat stat = zkClient.exists("/aaa", false);
+    if (stat == null) {
+        System.out.println("节点不存在...");
+        return;
+    }
+    zkClient.delete("/aaa", stat.getVersion());
+}
+```    
+### 11、删除非空节点,递归实现   
+```java
+//封装一个方法,方便递归调用
+public void deleteAll(String path, ZooKeeper zk) throws KeeperException, InterruptedException {
+    //判断节点是否存在
+    Stat stat = zkClient.exists(path, false);
+    if (stat == null) {
+        System.out.println("节点不存在...");
+        return;
+    }
+    //先获取当前传入节点下的所有子节点
+    List<String> children = zk.getChildren(path, false);
+    if (children.isEmpty()) {
+        //说明传入的节点没有子节点,可以直接删除
+        zk.delete(path, stat.getVersion());
+    } else {
+        //如果传入的节点有子节点,循环所有子节点
+        for (String child : children) {
+            //删除子节点,但是不知道子节点下面还有没有子节点,所以递归调用
+            deleteAll(path + "/" + child, zk);  
+        }
+        //删除完所有子节点以后,记得删除传入的节点
+        zk.delete(path, stat.getVersion());
+    }
+}
+//测试deleteAll
+@Test
+public void testDeleteAll() throws KeeperException, InterruptedException {
+    deleteAll("/atguigu",zkClient);
+}
+```