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集群规划:
首先要有三台服务器节点,可以是用vmware软件来生成虚拟服务器。命名为: hadoop102、hadoop103和hadoop104,在这三个节点上部署Zookeeper。解压安装
配置zoo.cfg文件
#######################cluster########################## server.2=hadoop102:2888:3888 server.3=hadoop103:2888:3888 server.4=hadoop104:2888:3888
(1)在/opt/module/zookeeper-3.4.10/zkData目录下创建一个myid的文件 touch myid 添加myid文件,注意一定要在linux里面创建,在notepad++里面很可能乱码 (2)编辑myid文件 vi myid 在文件中添加与server对应的编号:如2 (3)拷贝配置好的zookeeper到其他机器上 scp -r zookeeper-3.4.10/ root@hadoop103.atguigu.com:/opt/app/ scp -r zookeeper-3.4.10/ root@hadoop104.atguigu.com:/opt/app/ 并分别修改myid文件中内容为3、4 (4)分别启动zookeeper [root@hadoop102 zookeeper-3.4.10]# bin/zkServer.sh start [root@hadoop103 zookeeper-3.4.10]# bin/zkServer.sh start [root@hadoop104 zookeeper-3.4.10]# bin/zkServer.sh start (5)查看状态 [root@hadoop102 zookeeper-3.4.10]# bin/zkServer.sh status JMX enabled by default Using config: /opt/module/zookeeper-3.4.10/bin/../conf/zoo.cfg Mode: follower [root@hadoop103 zookeeper-3.4.10]# bin/zkServer.sh status JMX enabled by default Using config: /opt/module/zookeeper-3.4.10/bin/../conf/zoo.cfg Mode: leader [root@hadoop104 zookeeper-3.4.5]# bin/zkServer.sh status JMX enabled by default Using config: /opt/module/zookeeper-3.4.10/bin/../conf/zoo.cfg Mode: follower
命令基本语法 | 功能描述 |
---|---|
help | 显示所有操作命令 |
ls path [watch] | 使用 ls 命令来查看当前znode中所包含的内容 |
ls2 path [watch] | 查看当前节点数据并能看到更新次数等数据 |
create | 普通创建 ; - s 含有序列 ; -e 临时(重启或者超时消失) |
get path [watch] | 获得节点的值 |
set | 设置节点的具体值 |
stat | 查看节点状态 |
delete | 删除节点 |
rmr | 递归删除节点 |
[atguigu@hadoop103 zookeeper-3.4.10]$ bin/zkCli.sh
[zk: localhost:2181(CONNECTED) 1] help
[zk: localhost:2181(CONNECTED) 0] ls / [zookeeper]
[zk: localhost:2181(CONNECTED) 1] ls2 / [zookeeper] cZxid = 0x0 ctime = Thu Jan 01 08:00:00 CST 1970 mZxid = 0x0 mtime = Thu Jan 01 08:00:00 CST 1970 pZxid = 0x0 cversion = -1 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 0 numChildren = 1
[zk: localhost:2181(CONNECTED) 2] create /app1 "hello app1" Created /app1 [zk: localhost:2181(CONNECTED) 4] create /app1/server101 "192.168.1.101" Created /app1/server101
[zk: localhost:2181(CONNECTED) 6] get /app1 hello app1 cZxid = 0x20000000a ctime = Mon Jul 17 16:08:35 CST 2017 mZxid = 0x20000000a mtime = Mon Jul 17 16:08:35 CST 2017 pZxid = 0x20000000b cversion = 1 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 10 numChildren = 1 [zk: localhost:2181(CONNECTED) 8] get /app1/server101 192.168.1.101 cZxid = 0x20000000b ctime = Mon Jul 17 16:11:04 CST 2017 mZxid = 0x20000000b mtime = Mon Jul 17 16:11:04 CST 2017 pZxid = 0x20000000b cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 13 numChildren = 0
[zk: localhost:2181(CONNECTED) 9] create -e /app-emphemeral 8888 1)在当前客户端是能查看到的 [zk: localhost:2181(CONNECTED) 10] ls / [app1, app-emphemeral, zookeeper] 2)退出当前客户端然后再重启客户端 [zk: localhost:2181(CONNECTED) 12] quit [atguigu@hadoop104 zookeeper-3.4.10]$ bin/zkCli.sh 3)再次查看根目录下短暂节点已经删除 [zk: localhost:2181(CONNECTED) 0] ls / [app1, zookeeper]
1)先创建一个普通的根节点app2 [zk: localhost:2181(CONNECTED) 11] create /app2 "app2" 2)创建带序号的节点 [zk: localhost:2181(CONNECTED) 13] create -s /app2/aa 888 Created /app2/aa0000000000 [zk: localhost:2181(CONNECTED) 14] create -s /app2/bb 888 Created /app2/bb0000000001 [zk: localhost:2181(CONNECTED) 15] create -s /app2/cc 888 Created /app2/cc0000000002 如果原节点下有1个节点,则再排序时从1开始,以此类推。 [zk: localhost:2181(CONNECTED) 16] create -s /app1/aa 888 Created /app1/aa0000000001
[zk: localhost:2181(CONNECTED) 2] set /app1 999
1)在104主机上注册监听/app1节点数据变化 [zk: localhost:2181(CONNECTED) 26] get /app1 watch 2)在103主机上修改/app1节点的数据 [zk: localhost:2181(CONNECTED) 5] set /app1 777 3)观察104主机收到数据变化的监听 WATCHER:: WatchedEvent state:SyncConnected type:NodeDataChanged path:/app1
1)在104主机上注册监听/app1节点的子节点变化 [zk: localhost:2181(CONNECTED) 1] ls /app1 watch [aa0000000001, server101] 2)在103主机/app1节点上创建子节点 [zk: localhost:2181(CONNECTED) 6] create /app1/bb 666 Created /app1/bb 3)观察104主机收到子节点变化的监听 WATCHER:: WatchedEvent state:SyncConnected type:NodeChildrenChanged path:/app1
[zk: localhost:2181(CONNECTED) 4] delete /app1/bb
[zk: localhost:2181(CONNECTED) 7] rmr /app2
[zk: localhost:2181(CONNECTED) 12] stat /app1 cZxid = 0x20000000a ctime = Mon Jul 17 16:08:35 CST 2017 mZxid = 0x200000018 mtime = Mon Jul 17 16:54:38 CST 2017 pZxid = 0x20000001c cversion = 4 dataVersion = 2 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 3 numChildren = 2
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(); } } }); }
// 创建子节点 @Test public void create() throws Exception { // 数据的增删改查 // 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("/eclipse", "hello zk".getBytes(), Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT); }
// 获取子节点 @Test public void getChildren() throws Exception { Listchildren = zkClient.getChildren("/", true); for (String child : children) { System.out.println(child); } // 延时阻塞 Thread.sleep(Long.MAX_VALUE); }
// 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"); }
需求:某分布式系统中,主节点可以有多台,可以动态上下线,任意一台客户端都能实时感知到主节点服务器的上下线
需求分析
具体实现:
(0)先在集群上创建/servers节点
[zk: localhost:2181(CONNECTED) 10] create /servers "servers"Created /servers
(1)服务器端代码:
import java.io.IOException;import org.apache.zookeeper.CreateMode;import org.apache.zookeeper.WatchedEvent;import org.apache.zookeeper.Watcher;import org.apache.zookeeper.ZooKeeper;import org.apache.zookeeper.ZooDefs.Ids;public class DistributeServer { private static String connectString = "hadoop102:2181,hadoop103:2181,hadoop104:2181"; private static int sessionTimeout = 2000; private ZooKeeper zk = null; private String parentNode = "/servers"; // 创建到zk的客户端连接 public void getConnect() throws IOException{ zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() { @Override public void process(WatchedEvent event) { } }); } // 注册服务器 public void registServer(String hostname) throws Exception{ String create = zk.create(parentNode + "/server", hostname.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL); System.out.println(hostname +" is noline "+ create); } // 业务功能 public void business(String hostname) throws Exception{ System.out.println(hostname+" is working ..."); Thread.sleep(Long.MAX_VALUE); } public static void main(String[] args) throws Exception { // 获取zk连接 DistributeServer server = new DistributeServer(); server.getConnect(); // 利用zk连接注册服务器信息 server.registServer(args[0]); // 启动业务功能 server.business(args[0]); }}
(2)客户端代码
import java.io.IOException;import java.util.ArrayList;import java.util.List;import org.apache.zookeeper.WatchedEvent;import org.apache.zookeeper.Watcher;import org.apache.zookeeper.ZooKeeper;public class DistributeClient { private static String connectString = "hadoop102:2181,hadoop103:2181,hadoop104:2181"; private static int sessionTimeout = 2000; private ZooKeeper zk = null; private String parentNode = "/servers"; private volatile ArrayListserversList = new ArrayList<>(); // 创建到zk的客户端连接 public void getConnect() throws IOException { zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() { @Override public void process(WatchedEvent event) { // 再次启动监听 try { getServerList(); } catch (Exception e) { e.printStackTrace(); } } }); } // 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); ArrayList servers = new ArrayList<>(); for (String child : children) { byte[] data = zk.getData(parentNode + "/" + child, false, null); servers.add(new String(data)); } // 把servers赋值给成员serverList,已提供给各业务线程使用 serversList = servers; System.out.println(serversList); } // 业务功能 public void business() throws Exception { System.out.println("client is working ...");Thread.sleep(Long.MAX_VALUE); } public static void main(String[] args) throws Exception { // 获取zk连接 DistributeClient client = new DistributeClient(); client.getConnect(); // 获取servers的子节点信息,从中获取服务器信息列表 client.getServerList(); // 业务进程启动 client.business(); }}
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