上一篇发布了近期的面试总结-Mysql篇，最近在读《从Paxos到Zookeeper分布式一致性原理与实践》的电子书，从上面学到不少，因此将部分api演示从头演练一遍形成demo代码。
zookeeper初始化构造方法
package com.coderman.zookeeper.clusterdemo.version2;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import java.io.IOException;
import java.util.concurrent.CountDownLatch;
/**
* @description:
* @author: Fanchunshuai
* @time: 2020/2/10 15:51
*/
public class ZKConstructDemo implements Watcher {
private static StringBuffer buffer = new StringBuffer();
private static CountDownLatch countDownLatch = new CountDownLatch(1);
private static final int SESSION_TIMEOUT = 5000;
protected static ZooKeeper zooKeeper;
static {
buffer.append("192.168.1.224:2184,");
buffer.append("192.168.1.224:2181,");
buffer.append("192.168.1.224:2182,");
buffer.append("192.168.1.224:2183,");
buffer.append("192.168.1.224:2185");
}
public static void main(String[] args) {
try {
//第一种初始化接口
zooKeeper = new ZooKeeper(buffer.toString(), SESSION_TIMEOUT, new ZKConstructDemo());
//第二种初始化接口增加了两个参数，为了复用session会话和密码
zooKeeper = new ZooKeeper(buffer.toString(), SESSION_TIMEOUT, new ZKConstructDemo(),zooKeeper.getSessionId(),zooKeeper.getSessionPasswd());
System.out.println(zooKeeper.getState());
} catch (IOException e) {
e.printStackTrace();
}
try {
countDownLatch.await();
System.out.println("zookeeper session established...");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
@Override
public void process(WatchedEvent watchedEvent) {
System.out.println("received watch event = "+watchedEvent);
if(Event.KeeperState.SyncConnected == watchedEvent.getState()){
countDownLatch.countDown();
}
}
}
zookeeper创建API的接口方法
package com.coderman.zookeeper.clusterdemo.version2;
import org.apache.zookeeper.*;
import java.io.IOException;
import java.util.concurrent.CountDownLatch;
/**
* @description:
* @author: Fanchunshuai
* @time: 2020/2/10 16:47
*/
/**
* 节点创建API
* zookeeper的节点创建api有两个重载方法
* 一个是同步调用，一个是异步调用
* 创建节点的参数如下：
* path:需要创建节点的路径 如/zookeeper/config
* data[]:节点创建后的初始内容
* acl:节点的ACL策略，是List类型，已经通过ZooDefs.Ids类初始化好了
* createMode:创建节点的类型或者模式,是枚举类型，通过CreateMode枚举类初始化好了
* cb:回调函数
* ctx:传递一个上下文对象，在回调方法执行的时候使用
* <p>
* 需要注意的是：无论是同步接口还是异步接口，zookeeper都不支持递归创建，即无法在父节点不存在的情况下创建子节点。
* 如果节点已经存在，那么创建同名节点将会抛出NodeExitsException异常。
* <p>
* 同步调用演示
*/
public class ZKCreateAPIDemo implements Watcher {
private static StringBuffer buffer = new StringBuffer();
private static CountDownLatch countDownLatch = new CountDownLatch(1);
private static final int SESSION_TIMEOUT = 5000;
protected static ZooKeeper zooKeeper;
static {
buffer.append("192.168.1.224:2184,");
buffer.append("192.168.1.224:2181,");
buffer.append("192.168.1.224:2182,");
buffer.append("192.168.1.224:2183,");
buffer.append("192.168.1.224:2185");
}
public static void main(String[] args) {
//createSyncCall();
createAsyncCall();
}
@Override
public void process(WatchedEvent watchedEvent) {
if (Event.KeeperState.SyncConnected == watchedEvent.getState()) {
countDownLatch.countDown();
}
}
/**
* 同步调用演示
*/
private static void createSyncCall() {
try {
//第一种初始化接口
zooKeeper = new ZooKeeper(buffer.toString(), SESSION_TIMEOUT, new ZKConstructDemo());
//第二种初始化接口增加了两个参数，为了复用session会话和密码
zooKeeper = new ZooKeeper(buffer.toString(), SESSION_TIMEOUT, new ZKConstructDemo(), zooKeeper.getSessionId(), zooKeeper.getSessionPasswd());
String path = "/hadoop";
byte[] data = "hadooper".getBytes();
//1.创建一个临时节点
String response = zooKeeper.create(path, data, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
System.out.println("response = " + response);
String path2 = "/hadoop2";
byte[] data2 = "hadooper2".getBytes();
//2.创建一个临时顺序节点
String response2 = zooKeeper.create(path2, data2, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
System.out.println("response2 = " + response2);
//3.创建一个持久节点
String path3 = "/hadoop3";
byte[] data3 = "hadooper3".getBytes();
String response3 = zooKeeper.create(path3, data3, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
System.out.println("response3 = " + response3);
//4.创建一个持久顺序节点
String path4 = "/hadoop4";
byte[] data4 = "hadooper4".getBytes();
String response4 = zooKeeper.create(path4, data4, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT_SEQUENTIAL);
System.out.println("response4 = " + response3);
} catch (IOException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (KeeperException e) {
e.printStackTrace();
}
try {
countDownLatch.await();
System.out.println("zookeeper session established...");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* 异步调用演示
*/
private static void createAsyncCall() {
String path = "/hadoopsync";
byte[] data = "hadoopersync".getBytes();
try {
//第一种初始化接口
zooKeeper = new ZooKeeper(buffer.toString(), SESSION_TIMEOUT, new ZKConstructDemo());
//第二种初始化接口增加了两个参数，为了复用session会话和密码
zooKeeper = new ZooKeeper(buffer.toString(), SESSION_TIMEOUT, new ZKConstructDemo(), zooKeeper.getSessionId(), zooKeeper.getSessionPasswd());
} catch (IOException e) {
e.printStackTrace();
}
//1.创建一个临时节点
zooKeeper.create(path, data, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL,
new IStringCallBack(), "the context");
//1.创建一个临时节点
zooKeeper.create(path, data, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL,
new IStringCallBack(), "the context");
try {
Thread.sleep(10000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* 字符串回调接口，除了这种类型的回调接口之外
* 如ACLCallback，DataCallback等。
*/
static class IStringCallBack implements AsyncCallback.StringCallback {
/**
* @param rc 响应码 0:接口调用成功 -4:客户端和服务端链接已经断开
* -110:指定节点已经存在。-112:会话已过期
* @param path 接口调用时传入API的数据节点的路径参数值
* @param ctx 接口调用时传入API的ctx参数值
* @param name 实际在服务端创建的节点名
*/
@Override
public void processResult(int rc, String path, Object ctx, String name) {
System.out.println("create path result:["
+ rc + ", " + path + ", " + ctx + ", real path name :" + name);
}
}
}
