zookeeper的简单使用

quit退出客户端

7、远程开启服务端

ssh 192.168.65.135 "source /etc/profile;/root/apps/zookeeper-3.4.5/bin/zkServer.sh start"

三、常用API

增删查改操作：

public class SimpleZkClient {

private static final String cOnnectString= "mini1:2181,mini2:2181,mini3:2181";
private static final int sessiOnTimeout= 2000;

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（应该是我们自己的事件处理逻辑）
System.out.println(event.getType() + "---" + event.getPath());
try {
zkClient.getChildren("/", true);
} catch (Exception e) {
}
}
});

}

/**
 * 数据的增删改查
 * 
 * @throws InterruptedException
 * @throws KeeperException
 */

// 创建数据节点到zk中
public void testCreate() throws KeeperException, InterruptedException {
// 参数1：要创建的节点的路径 参数2：节点大数据 参数3：节点的权限 参数4：节点的类型
String nodeCreated = zkClient.create("/eclipse", "hellozk".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
//上传的数据可以是任何类型，但都要转成byte[]
}

//判断znode是否存在
@Test
public void testExist() throws Exception{
Stat stat = zkClient.exists("/eclipse", false);
System.out.println(stat==null?"not exist":"exist");


}

// 获取子节点
@Test
public void getChildren() throws Exception {
List children = zkClient.getChildren("/", true);
for (String child : children) {
System.out.println(child);
}
Thread.sleep(Long.MAX_VALUE);
}

//获取znode的数据
@Test
public void getData() throws Exception {

byte[] data = zkClient.getData("/eclipse", false, null);
System.out.println(new String(data));

}

//删除znode
@Test
public void deleteZnode() throws Exception {

//参数2：指定要删除的版本，-1表示删除所有版本
zkClient.delete("/eclipse", -1);


}
//删除znode
@Test
public void setData() throws Exception {

zkClient.setData("/app1", "imissyou angelababy".getBytes(), -1);

byte[] data = zkClient.getData("/app1", false, null);
System.out.println(new String(data));
}
}

实现对分布式系统中服务器上下线的监控：

public class DistributedServer {
private static final String cOnnectString= "mini1:2181,mini2:2181,mini3:2181";
private static final int sessiOnTimeout= 2000;
private static final String parentNode = "/servers";

private ZooKeeper zk = null;

/**
 * 创建到zk的客户端连接
 * 
 * @throws Exception
 */
public void getConnect() throws Exception {

zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
@Override
public void process(WatchedEvent event) {
// 收到事件通知后的回调函数（应该是我们自己的事件处理逻辑）
System.out.println(event.getType() + "---" + event.getPath());
try {
zk.getChildren("/", true);
} catch (Exception e) {
}
}
});

}

/**
 * 向zk集群注册服务器信息
 * 
 * @param hostname
 * @throws Exception
 */
public void registerServer(String hostname) throws Exception {

String create = zk.create(parentNode + "/server", hostname.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
System.out.println(hostname + "is online.." + create);

}

/**
 * 业务功能
 * 
 * @throws InterruptedException
 */
public void handleBussiness(String hostname) throws InterruptedException {
System.out.println(hostname + "start working.....");
Thread.sleep(Long.MAX_VALUE);
}

public static void main(String[] args) throws Exception {

// 获取zk连接
DistributedServer server = new DistributedServer();
server.getConnect();

// 利用zk连接注册服务器信息
server.registerServer(args[0]);

// 启动业务功能
server.handleBussiness(args[0]);

}

}

public class DistributedClient {private static final String cOnnectString= "mini1:2181,mini2:2181,mini3:2181";private static final int sessiOnTimeout= 2000;private static final String parentNode = "/servers";// 注意:加volatile的意义何在？private volatile List serverList;private ZooKeeper zk = null;/** * 创建到zk的客户端连接 *  * @throws Exception */public void getConnect() throws Exception {zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() {@Overridepublic void process(WatchedEvent event) {// 收到事件通知后的回调函数（应该是我们自己的事件处理逻辑）try {//重新更新服务器列表，并且注册了监听getServerList();} catch (Exception e) {}}});}/** * 获取服务器信息列表 *  * @throws Exception */public void getServerList() throws Exception {// 获取服务器子节点信息，并且对父节点进行监听List children = zk.getChildren(parentNode, true);// 先创建一个局部的list来存服务器信息List servers = new ArrayList();for (String child : children) {// child只是子节点的节点名byte[] data = zk.getData(parentNode + "/" + child, false, null);servers.add(new String(data));}// 把servers赋值给成员变量serverList，已提供给各业务线程使用serverList = servers;//打印服务器列表System.out.println(serverList);}/** * 业务功能 *  * @throws InterruptedException */public void handleBussiness() throws InterruptedException {System.out.println("client start working.....");Thread.sleep(Long.MAX_VALUE);}public static void main(String[] args) throws Exception {// 获取zk连接DistributedClient client = new DistributedClient();client.getConnect();// 获取servers的子节点信息（并监听），从中获取服务器信息列表client.getServerList();// 业务线程启动client.handleBussiness();}}