一：Zookeeper使用

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? ? 1.客戶端腳本使用

? ? 主要命令如下：

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? ? ? ? 1）打開客戶端

./zkCli.sh --會默認連接本地2181端口 ./zkCli.sh -server ip:port --打開指定IP：port

? ? ? ? 2）添加節點

create [-s] [-e] path data create /zk_test 111 --創建根節點/下子節點 zk_test 值為111

? ? ? ? 3）修改節點值

set path data [version] set /zk_test 121 --修改/zk_test 值為121

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? 4）查看節點

ls path [watch] ls /zk_test --查看/zk_test的值 ls / --查看根節點下所有節點

? ? ? ? 5）刪除節點

delete path [version] delete /zk_test --刪除/zk_test節點

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? ? ? ? 注意：如果該節點下有子節點，則不能刪除該節點，需要先刪除子節點

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? ? 使用JavaAPI前提條件：本人使用zookeeper3.4.11，maven管理，pom.xml如下

<!-- https://mvnrepository.com/artifact/org.apache.zookeeper/zookeeper --><dependency><groupId>org.apache.zookeeper</groupId><artifactId>zookeeper</artifactId><version>3.4.11</version></dependency><dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.15</version> <exclusions> <exclusion> <groupId>javax.jms</groupId> <artifactId>jms</artifactId> </exclusion> <exclusion> <groupId>com.sun.jdmk</groupId> <artifactId>jmxtools</artifactId> </exclusion> <exclusion> <groupId>com.sun.jmx</groupId> <artifactId>jmxri</artifactId> </exclusion> </exclusions> </dependency>

? ?由于jmxtools相關jar包需要認證，就直接exclude，用戶也可以單獨下載之后放到m2

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? ? 2.創建ZooKeeper客戶端（JavaAPI）

? ? ? ? 構造方法如下：

ZooKeeper(java.lang.String connectString, int sessionTimeout, Watcher watcher)To create a ZooKeeper client object, the application needs to pass a connection string containing a comma separated list of host:port pairs, each corresponding to a ZooKeeper server.ZooKeeper(java.lang.String connectString, int sessionTimeout, Watcher watcher, boolean canBeReadOnly)To create a ZooKeeper client object, the application needs to pass a connection string containing a comma separated list of host:port pairs, each corresponding to a ZooKeeper server.ZooKeeper(java.lang.String connectString, int sessionTimeout, Watcher watcher, long sessionId, byte[] sessionPasswd)To create a ZooKeeper client object, the application needs to pass a connection string containing a comma separated list of host:port pairs, each corresponding to a ZooKeeper server.ZooKeeper(java.lang.String connectString, int sessionTimeout, Watcher watcher, long sessionId, byte[] sessionPasswd, boolean canBeReadOnly)To create a ZooKeeper client object, the application needs to pass a connection string containing a comma separated list of host:port pairs, each corresponding to a ZooKeeper server.

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? ? ? ? * Watch 是一個監控器，用于監控zookeeper狀態變化，當狀態變化時，會回調相關方法

? ? ? ? * sessionID和sessionPasswd 分別代表會話ID和會話秘鑰，這兩個參數能夠確定一個會話

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? ? ? ? 使用方式如下：（寫成簡單單例方式來用）

public class ZookeeperInstance {private static ZooKeeper zookeeper = null;public static final String CONNECT_STRING = "localhost:2181";public static final int SESSION_TIME_OUT = 5000;static CountDownLatch cdl = new CountDownLatch(1);public static ZooKeeper getInstance(){if(null == zookeeper){try {zookeeper = new ZooKeeper(CONNECT_STRING, SESSION_TIME_OUT, new ZookeeperWatcher());//由于zookeeper的創建是異步的，直接返回的并不是可用的zookeeper，狀態也是States.CONNECTING，真正連接成功后狀態變為CONNECTEDcdl.await();} catch (IOException e) {e.printStackTrace();} catch (InterruptedException e) {e.printStackTrace();}}return zookeeper;}//異步處理類，當狀態變化時，會回調process方法static class ZookeeperWatcher implements Watcher{@Overridepublic void process(WatchedEvent event) {System.out.println("receive watched event:" + event);if(KeeperState.SyncConnected == event.getState()){cdl.countDown();}}} }

?? ? ? 注意：zookeeper的創建是異步的，

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? ? 3.創建zookeeper節點（JavaAPI）

? ? ? ? 方法如下所示：

java.lang.String create(java.lang.String path, byte[] data, java.util.List<ACL> acl, CreateMode createMode)Create a node with the given path.void create(java.lang.String path, byte[] data, java.util.List<ACL> acl, CreateMode createMode, AsyncCallback.StringCallback cb, java.lang.Object ctx)The asynchronous version of create.

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? ? ? ? *?path 節點的路徑

? ? ? ? * data 節點的初始值

? ? ? ? * acl 節點的訪問控制權限設置 （用戶可使用ZooDefs.Ids下的值，可選項有?OPEN_ACL_UNSAFE，?CREATOR_ALL_ACL，?READ_ACL_UNSAFE）

? ? ? ? * createMode?節點的創建策略?（用戶可使用?CreateMode下的值，可選項有PERSISTENT ，PERSISTENT_SEQUENTIAL，?EPHEMERAL，EPHEMERAL_SEQUENTIAL?）

? ? ? ? ? ? PERSISTENT意味持久化節點，客戶端斷開連接后，節點依舊存在

? ? ? ? ? ? EPHEMERAL臨時節點，客戶端斷開連接后，節點就刪除

? ? ? ? ? ? SEQUENTIAL會在節點path后加上一個順序碼

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? ??? ???使用方式如下：

? ??? ? 1）同步創建
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//1.同步方式創建節點 //1.1 CreateMode.EPHEMERAL 臨時節點 在客戶端斷開的時候斷開連接 String path1 = zookeeper.create("/z_test_e", "111".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL); System.out.println(path1); String path2 = zookeeper.create("/z_test_e_s", "222".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL); System.out.println(path2);//1.2 CreateMode.PERSISTENT 持久化節點 String path3 = zookeeper.create("/z_test_p", "111".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); System.out.println(path3); String path4 = zookeeper.create("/z_test_p_s", "222".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT_SEQUENTIAL); System.out.println(path4);

? ? ???2）異步創建

//2.異步方式創建節點 zookeeper.create("/z_test_asyn_p_", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT, new StringCallbackImpl(), "i am context"); zookeeper.create("/z_test_asyn_p_s", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT_SEQUENTIAL, new StringCallbackImpl(), "i am context"); try {Thread.sleep(10000);//這個需要加上，因為創建節點是異步操作， } catch (InterruptedException e) {e.printStackTrace(); }static class StringCallbackImpl implements AsyncCallback.StringCallback{@Overridepublic void processResult(int rc, String path, Object ctx, String name) {System.out.println("create path result:" + rc + "," + path + "," + ctx + ",real name :" + name);} }

? ? ? ? 注意：由于此時的節點是異步創建，所以需要在最后的時候加上sleep，如果直接結束，節點有可能還沒創建成功

? ? ? ? processResult中的參數rc是響應碼（值可參考?org.apache.zookeeper.KeeperException.Code，0代表成功）

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? ? 4.修改zookeeper節點值（JavaAPI）

? ? ? ? 方法如下所示：

Stat setData(java.lang.String path, byte[] data, int version)Set the data for the node of the given path if such a node exists and the given version matches the version of the node (if the given version is -1, it matches any node's versions).void setData(java.lang.String path, byte[] data, int version, AsyncCallback.StatCallback cb, java.lang.Object ctx)The asynchronous version of setData.

?? ? ???使用方式如下：

Stat stat = zookeeper.setData("/z_test_p", "112211".getBytes(), 3); System.out.println("setData res:" + stat);zookeeper.setData("/z_test_p", "1111".getBytes(), 4, new AsyncCallback.StatCallback() {@Overridepublic void processResult(int rc, String path, Object ctx, Stat stat) {System.out.println("setData res:" + stat);} }, "setData");Thread.sleep(10000);

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注意：一定要設置正確的version，如果該version不存在，則會報錯；version=-1匹配節點所有的version

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? ? 5.查看子節點（JavaAPI）

? ? ? ? 方法如下所示：

java.util.List<java.lang.String> getChildren(java.lang.String path, boolean watch)Return the list of the children of the node of the given path.void getChildren(java.lang.String path, boolean watch, AsyncCallback.Children2Callback cb, java.lang.Object ctx)The asynchronous version of getChildren.void getChildren(java.lang.String path, boolean watch, AsyncCallback.ChildrenCallback cb, java.lang.Object ctx)The asynchronous version of getChildren.java.util.List<java.lang.String> getChildren(java.lang.String path, boolean watch, Stat stat)For the given znode path return the stat and children list.java.util.List<java.lang.String> getChildren(java.lang.String path, Watcher watcher)Return the list of the children of the node of the given path.void getChildren(java.lang.String path, Watcher watcher, AsyncCallback.Children2Callback cb, java.lang.Object ctx)The asynchronous version of getChildren.void getChildren(java.lang.String path, Watcher watcher, AsyncCallback.ChildrenCallback cb, java.lang.Object ctx)The asynchronous version of getChildren.java.util.List<java.lang.String> getChildren(java.lang.String path, Watcher watcher, Stat stat)For the given znode path return the stat and children list.

? ? ? ? 使用方式如下：

//同步 List<String> children = zookeeper.getChildren("/", true); System.out.println(Arrays.toString(children.toArray()));//異步 zookeeper.getChildren("/", true, new AsyncCallback.Children2Callback() {@Overridepublic void processResult(int rc, String path, Object ctx, List<String> children, Stat stat) {System.out.println("children:"+children);} }, "getChildren");Thread.sleep(10000);

?? ? ? 注意：用戶可自定義實現Children2Callback接口，用于監控當前節點的子節點變化，如有變化，會回調processResult方法

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? ??6.查看節點值（JavaAPI）

? ? ? ? 方法如下所示：

void getData(java.lang.String path, boolean watch, AsyncCallback.DataCallback cb, java.lang.Object ctx)The asynchronous version of getData.byte[] getData(java.lang.String path, boolean watch, Stat stat)Return the data and the stat of the node of the given path.void getData(java.lang.String path, Watcher watcher, AsyncCallback.DataCallback cb, java.lang.Object ctx)The asynchronous version of getData.byte[] getData(java.lang.String path, Watcher watcher, Stat stat)Return the data and the stat of the node of the given path.

? ? ? ? 使用方式如下所示：

//同步 byte[] data = zookeeper.getData("/z_test_p", true, new Stat()); System.out.println(new String(data));//異步 zookeeper.getData("/z_test_p", true, new AsyncCallback.DataCallback() {@Overridepublic void processResult(int rc, String path, Object ctx, byte[] data, Stat stat) {System.out.println("data:" + new String(data) + ",[" + stat +"]");} }, "getData");Thread.sleep(10000);

? ?? ? 注意：用戶可自定義實現DataCallback接口，用戶監控當前節點的值變化

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? ???7.刪除節點（JavaAPI）

? ? ? ? 方法如下所示：

void delete(java.lang.String path, int version)Delete the node with the given path.void delete(java.lang.String path, int version, AsyncCallback.VoidCallback cb, java.lang.Object ctx)The asynchronous version of delete.

? ? ? ? 使用方式如下

//直接刪除 zookeeper.delete("/z_test_asyn_p_", 0);//異步刪除 zookeeper.delete("/z_test_e", 0, new AsyncCallback.VoidCallback() {@Overridepublic void processResult(int rc, String path, Object ctx) {System.out.println("delete path result:" + rc + "," + path + "," + ctx );} }, "delete this path");Thread.sleep(10000);

? ? ? ? 注意：只允許刪除葉子節點，如果當前節點還有子節點，則無法刪除?

? ? 8.權限認證

? ? ? ? 添加權限方法如下：

void addAuthInfo(java.lang.String scheme, byte[] auth)Add the specified scheme:auth information to this connection.

? ? ? ? schema權限模式有：

? ? ? ? * ip （針對某個特定的IP）

? ? ? ? * digest （常用模式，形如 username:password）

? ? ? ? * world （開放模式，對所有用戶開放）

? ? ? ? * super （超級管理員模式，可以對任何節點進行操作）

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? ? ? ? 使用方式如下：

String path ="/act1"; CountDownLatch cdl = new CountDownLatch(1); try {//給當前zookeeper客戶端添加權限zookeeper.addAuthInfo("digest", "zhangsan:123".getBytes());//用戶注冊模式zookeeper.create(path, "data".getBytes(), Ids.CREATOR_ACL_UNSAFE, CreateMode.PERSISTENT, new AsyncCallback.StringCallback() {@Overridepublic void processResult(int rc, String path, Object ctx, String name) {System.out.println("create path result:" + rc + "," + path + "," + ctx + ",real name :" + name); cdl.countDown();}}, "createNode");cdl.await(); } ommit ...

? ? ? ? 這樣創建出的的節點/act1就除了zhangsan的其他普通用戶（admin除外）就無法進行訪問

? ??? ??注意：ACL需要是 CREATOR_ACL_UNSAFE，表示只有該創建者擁有增刪改查權限

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? ? ? ? 下面用其他客戶端訪問

//重新獲取客戶端，定義為其他用戶名密碼 ZooKeeper zookeeper1 = new ZooKeeper(ZookeeperInstance.CONNECT_STRING, ZookeeperInstance.SESSION_TIME_OUT, new ZookeeperWatcher()); zookeeper1.addAuthInfo("digest", "lisi:321".getBytes()); Thread.sleep(3000); //用其他賬戶來讀取/act數據 byte[] data = zookeeper1.getData(path, true, null); System.out.println(new String(data));

? ? ? ? 會報錯，KeeperErrorCode = NoAuth for /act1




參考：

從Paxos到Zookeeper? 分布式一致性原理與實踐（倪超）

zookeeper3.4.11 API

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