ZooKeeper 4. Zookeeper实战（开发重点）
4.1 分布式安装部署
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新建文件夹
/opt/zk_cluster -
将zookeeper压缩包加压到文件夹下，并重命名为cluster1
tar -zxvf apache-zookeeper-3.5.6-bin.tar.gz -C ./zk_cluster/ -
在cluster1里新建文件夹
zkData -
在zkData文件夹下新建文件myid，内容为1
echo 1 >> cluster1/zkData/myid -
复制conf目录下的zoo_sample.cfg文件为zoo.cfg
cp zoo_sample.cfg zoo.cfg -
修改zoo.cfg的内容
dataDir=/opt/zk_cluster/cluster1/zkData clientPort=2187 ###########Cluster################## server.1=192.168.181.128:12887:13887 server.2=192.168.181.128:12888:13888 server.3=192.168.181.128:12889:13889 -
将cluster1复制为cluster2、cluster3
cp -r cluster1/ cluster2 cp -r cluster1/ cluster3 -
将cluster2和cluster3中的zkData/myid内的内容修改为2、3
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修改cluster2和cluster3中的zoo.cfg的内容
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验证
启动三个ZooKeeper，查看状态
./cluster1/bin/zkServer.sh start ./cluster1/bin/zkServer.sh status[root@hwjsLinux zk_cluster]# ./cluster1/bin/zkServer.sh status /usr/bin/java ZooKeeper JMX enabled by default Using config: /opt/zk_cluster/cluster1/bin/../conf/zoo.cfg Client port found: 2187. Client address: localhost. Mode: follower
4.2 客户端命令行操作
| 命令 | 描述 |
|---|---|
| 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 |
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启动客户端
./zkCli.sh -server localhost:2187 -
显示所有操作命令
help -
查看当前znode中所包含的内容
[zk: localhost:2181(CONNECTED) 0] ls / [zookeeper] -
查看当前节点详细数据
[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 -
分别创建2个普通节点
[zk: localhost:2181(CONNECTED) 3] create /sanguo "jinlian" Created /sanguo [zk: localhost:2181(CONNECTED) 4] create /sanguo/shuguo "liubei" Created /sanguo/shuguo -
获得节点的值
[zk: localhost:2181(CONNECTED) 5] get /sanguo jinlian cZxid = 0x100000003 ctime = Wed Aug 29 00:03:23 CST 2018 mZxid = 0x100000003 mtime = Wed Aug 29 00:03:23 CST 2018 pZxid = 0x100000004 cversion = 1 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 7 numChildren = 1 [zk: localhost:2181(CONNECTED) 6] get /sanguo/shuguo liubei cZxid = 0x100000004 ctime = Wed Aug 29 00:04:35 CST 2018 mZxid = 0x100000004 mtime = Wed Aug 29 00:04:35 CST 2018 pZxid = 0x100000004 cversion = 0 dataVersion = 0 aclVersion = 0 ephemeralOwner = 0x0 dataLength = 6 numChildren = 0 -
创建短暂节点
[zk: localhost:2181(CONNECTED) 7] create -e /sanguo/wuguo "zhouyu" Created /sanguo/wuguo（1）在当前客户端是能查看到的
[zk: localhost:2181(CONNECTED) 3] ls /sanguo [wuguo, shuguo]（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 /sanguo [shuguo] -
创建带序号的节点
（1）先创建一个普通的根节点/sanguo/weiguo
[zk: localhost:2181(CONNECTED) 1] create /sanguo/weiguo "caocao"
Created /sanguo/weiguo
（2）创建带序号的节点
[zk: localhost:2181(CONNECTED) 2] create -s /sanguo/weiguo/xiaoqiao "jinlian"
Created /sanguo/weiguo/xiaoqiao0000000000
[zk: localhost:2181(CONNECTED) 3] create -s /sanguo/weiguo/daqiao "jinlian"
Created /sanguo/weiguo/daqiao0000000001
[zk: localhost:2181(CONNECTED) 4] create -s /sanguo/weiguo/diaocan "jinlian"
Created /sanguo/weiguo/diaocan0000000002
如果原来没有序号节点，序号从0开始依次递增。如果原节点下已有2个节点，则再排序时从2开始，以此类推。
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修改节点数据值
[zk: localhost:2181(CONNECTED) 6] set /sanguo/weiguo "simayi" -
节点的值变化监听
（1）在hadoop104主机上注册监听/sanguo节点数据变化
[zk: localhost:2181(CONNECTED) 26] [zk: localhost:2181(CONNECTED) 8] get /sanguo watch
（2）在hadoop103主机上修改/sanguo节点的数据
[zk: localhost:2181(CONNECTED) 1] set /sanguo "xisi"
（3）观察hadoop104主机收到数据变化的监听
WATCHER::
WatchedEvent state:SyncConnected type:NodeDataChanged path:/sanguo
- 节点的子节点变化监听（路径变化）
（1）在hadoop104主机上注册监听/sanguo节点的子节点变化
[zk: localhost:2181(CONNECTED) 1] ls /sanguo watch
[aa0000000001, server101]
（2）在hadoop103主机/sanguo节点上创建子节点
[zk: localhost:2181(CONNECTED) 2] create /sanguo/jin "simayi"
Created /sanguo/jin
（3）观察hadoop104主机收到子节点变化的监听
WATCHER::
WatchedEvent state:SyncConnected type:NodeChildrenChanged path:/sanguo
- 删除节点
[zk: localhost:2181(CONNECTED) 4] delete /sanguo/jin
- 递归删除节点
[zk: localhost:2181(CONNECTED) 15] rmr /sanguo/shuguo
- 查看节点状态
[zk: localhost:2181(CONNECTED) 17] stat /sanguo
cZxid = 0x100000003
ctime = Wed Aug 29 00:03:23 CST 2018
mZxid = 0x100000011
mtime = Wed Aug 29 00:21:23 CST 2018
pZxid = 0x100000014
cversion = 9
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 4
numChildren = 1
4.3 API应用
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pom.xml
<dependency> <groupId>org.apache.zookeeper</groupId> <artifactId>zookeeper</artifactId> <version>3.4.10</version> </dependency> -
测试代码
public class TestZookeeper { // private String connectString="hadoop102:2181,hadoop103:2181,hadoop104:2181"; private String connectString="192.168.181.128:2187,192.168.181.128:2188,192.168.181.128:2189"; 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 event) { System.out.println("---------start----------"); List<String> children; try { children = zkClient.getChildren("/", true); for (String child : children) { System.out.println(child); } System.out.println("---------end----------"); } catch (Exception e) { e.printStackTrace(); } } }); } // 1 创建节点 @Test public void createNode() throws KeeperException, InterruptedException{ String path = zkClient.create("/atguigu", "dahaigezuishuai".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); System.out.println(path); } // 2 获取子节点 并监控节点的变化 @Test public void getDataAndWatch() throws KeeperException, InterruptedException{ List<String> children = zkClient.getChildren("/", true); for (String child : children) { System.out.println(child); } Thread.sleep(Long.MAX_VALUE); } // 3 判断节点是否存在 @Test public void exist() throws KeeperException, InterruptedException{ Stat stat = zkClient.exists("/atguigu", false); System.out.println(stat==null? "not exist":"exist"); } }
4.4 监听服务器节点动态上下线案例
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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。
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具体实现
服务端代码
public class DistributeServer { public static void main(String[] args) throws Exception { String hostname = "test4"; DistributeServer server = new DistributeServer(); // 1 连接zookeeper集群 server.getConnect(); // 2 注册节点 server.regist(hostname); // 3 业务逻辑处理 server.business(); } private void business() throws InterruptedException { Thread.sleep(Long.MAX_VALUE); } private void regist(String hostname) throws KeeperException, InterruptedException { String path = zkClient.create("/servers/server", hostname.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL); System.out.println(hostname +" is online "); } // private String connectString = "hadoop102:2181,hadoop103:2181,hadoop104:2181"; private String connectString="192.168.181.128:2187,192.168.181.128:2188,192.168.181.128:2189"; private int sessionTimeout = 2000; private ZooKeeper zkClient; private void getConnect() throws IOException { zkClient = new ZooKeeper(connectString , sessionTimeout , new Watcher() { @Override public void process(WatchedEvent event) { // TODO Auto-generated method stub } }); } }客户端代码
public class DistributeClient { public static void main(String[] args) throws IOException, KeeperException, InterruptedException { DistributeClient client = new DistributeClient(); // 1 获取zookeeper集群连接 client.getConnect(); // 2 注册监听 client.getChlidren(); // 3 业务逻辑处理 client.business(); } private void business() throws InterruptedException { Thread.sleep(Long.MAX_VALUE); } private void getChlidren() throws KeeperException, InterruptedException { List<String> children = zkClient.getChildren("/servers", true); // 存储服务器节点主机名称集合 ArrayList<String> hosts = new ArrayList<>(); for (String child : children) { byte[] data = zkClient.getData("/servers/"+child, false, null); hosts.add(new String(data)); } // 将所有在线主机名称打印到控制台 System.out.println(hosts); } // private String connectString = "hadoop102:2181,hadoop103:2181,hadoop104:2181"; private String connectString="192.168.181.128:2187,192.168.181.128:2188,192.168.181.128:2189"; private int sessionTimeout = 2000; private ZooKeeper zkClient; private void getConnect() throws IOException { zkClient = new ZooKeeper(connectString , sessionTimeout , new Watcher() { @Override public void process(WatchedEvent event) { try { getChlidren(); } catch (KeeperException e) { e.printStackTrace(); } catch (InterruptedException e) { e.printStackTrace(); } } }); } } -
测试
客户端随着服务端的启动、停止动态获得服务器信息。