20200209 ZooKeeper 4. Zookeeper实战（开发重点）

其他 2020-02-09 17:01:28 阅读次数: 0

ZooKeeper 4. Zookeeper实战（开发重点）

4.1 分布式安装部署

  1. 新建文件夹/opt/zk_cluster

  2. 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/

  3. 在cluster1里新建文件夹zkData

  4. 在zkData文件夹下新建文件myid，内容为1

    echo 1 >> cluster1/zkData/myid

  5. 复制conf目录下的zoo_sample.cfg文件为zoo.cfg

    cp zoo_sample.cfg zoo.cfg

  6. 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

  7. 将cluster1复制为cluster2、cluster3

    cp -r cluster1/ cluster2
cp -r cluster1/ cluster3

  8. 将cluster2和cluster3中的zkData/myid内的内容修改为2、3

  9. 修改cluster2和cluster3中的zoo.cfg的内容

  10. 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

  1. 启动客户端

    ./zkCli.sh -server localhost:2187

  2. 显示所有操作命令

    help

  3. 查看当前znode中所包含的内容

    [zk: localhost:2181(CONNECTED) 0] ls /
[zookeeper]

  4. 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

  5. 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

  6. 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

  7. 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]

  8. 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。

  1. 修改节点数据值

    [zk: localhost:2181(CONNECTED) 6] set /sanguo/weiguo "simayi"

  2. 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
  1. 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
  1. 删除节点
[zk: localhost:2181(CONNECTED) 4] delete /sanguo/jin
  1. 递归删除节点
[zk: localhost:2181(CONNECTED) 15] rmr /sanguo/shuguo
  1. 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

  1. pom.xml

         <dependency>
         <groupId>org.apache.zookeeper</groupId>
         <artifactId>zookeeper</artifactId>
         <version>3.4.10</version>
     </dependency>

  2. 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

  1. 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。

  2. 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();
             }
         }
     });

 }
}

  3. 测试

    客户端随着服务端的启动、停止动态获得服务器信息。

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