目录
0. 相关文章链接
大数据基础知识点 文章汇总
1. IDEA环境搭建
在IDEA中创建一个Maven工程
其中pom依赖如下：
<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>
<dependency>
<groupId>org.apache.curator</groupId>
<artifactId>curator-framework</artifactId>
<version>4.3.0</version>
</dependency>
<dependency>
<groupId>org.apache.curator</groupId>
<artifactId>curator-recipes</artifactId>
<version>4.3.0</version>
</dependency>
<dependency>
<groupId>org.apache.curator</groupId>
<artifactId>curator-client</artifactId>
<version>4.3.0</version>
</dependency>
</dependencies>在resources下添加log4j.properties文件，具体内容如下：
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
创建对应的包名和类名
2. 创建 ZooKeeper 客户端
具体代码如下：
// 注意：逗号左右不能有空格
private String connectString = "yangshibiao:2181";
private int sessionTimeout = 2000;
private ZooKeeper zkClient;
@Before
public void init() throws IOException {
zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
@Override
public void process(WatchedEvent watchedEvent) {
// 收到事件通知后的回调函数（用户的业务逻辑）
System.out.println(watchedEvent.getType() + "--" + watchedEvent.getPath());
// 再次启动监听
try {
List<String> children = zkClient.getChildren("/", true);
for (String child : children) {
System.out.println("init==> "+child);
}
} catch (Exception e) {
e.printStackTrace();
}
}
});
}3. 创建子节点
具体代码如下：
// 创建子节点
@Test
public void create() throws KeeperException, InterruptedException {
// 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(
"/yangshibiao",
"ss.avi".getBytes(),
ZooDefs.Ids.OPEN_ACL_UNSAFE,
CreateMode.PERSISTENT
);
}4. 获取子节点并监听节点变化
具体代码如下：
// 获取子节点
@Test
public void getChildren() throws KeeperException, InterruptedException {
List<String> children = zkClient.getChildren("/", true);
for (String child : children) {
System.out.println("getChildren ==> " + child);
}
// 延时
Thread.sleep(Long.MAX_VALUE);
}当在idea中启动程序后会将 zookeeper 跟目录下对应的子节点打印出来
但此时通过 zookeeper 命令行在创建一个 子节点，然后观察IDEA命令行会发现会重新打印所有子节点
当通过 zookeeper 命令行删除一个子节点时，同样的会重新打印所有子节点
5. 判断 Znode 是否存在
具体代码如下：
// 判断 znode 是否存在
@Test
public void exist() throws KeeperException, InterruptedException {
Stat stat = zkClient.exists("/yangshibiao", false);
System.out.println(stat == null ? "not exist " : "exist");
}6. 上述操作代码汇总
package com.ouyang.zookeeper;
import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import org.junit.Before;
import org.junit.Test;
import java.io.IOException;
import java.util.List;
/**
* @ date: 2022/4/6
* @ author: yangshibiao
* @ desc: 项目描述
*/
public class ZookeeperClient {
// 注意：逗号左右不能有空格
private String connectString = "yangshibiao:2181";
private int sessionTimeout = 2000;
private ZooKeeper zkClient;
@Before
public void init() throws IOException {
zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
@Override
public void process(WatchedEvent watchedEvent) {
// 收到事件通知后的回调函数（用户的业务逻辑）
System.out.println(watchedEvent.getType() + "--" + watchedEvent.getPath());
// 再次启动监听
try {
List<String> children = zkClient.getChildren("/", true);
for (String child : children) {
System.out.println("init==> "+child);
}
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
// 创建子节点
@Test
public void create() throws KeeperException, InterruptedException {
// 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(
"/yangshibiao",
"ss.avi".getBytes(),
ZooDefs.Ids.OPEN_ACL_UNSAFE,
CreateMode.PERSISTENT
);
}
// 获取子节点
@Test
public void getChildren() throws KeeperException, InterruptedException {
List<String> children = zkClient.getChildren("/", true);
for (String child : children) {
System.out.println("getChildren ==> " + child);
}
// 延时
Thread.sleep(Long.MAX_VALUE);
}
// 判断 znode 是否存在
@Test
public void exist() throws KeeperException, InterruptedException {
Stat stat = zkClient.exists("/yangshibiao", false);
System.out.println(stat == null ? "not exist " : "exist");
}
}
7. 客户端向服务端写数据流程
7.1. 写流程之写入请求直接发送给Leader节点
7.2. 写流程之写入请求发送给follower节点
注：其他相关文章链接由此进（包括Zookeeper在内的各大数据组件相关博文） -> 大数据基础知识点 文章汇总