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[ASP.net教程](原) 2.1 Zookeeper原生API使用


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Zookeeper原生API使用

1、jar包引入,演示版本为3.4.6,非maven项目,可以下载jar包导入到项目中

  

<dependency>      <groupId>org.apache.zookeeper</groupId>      <artifactId>zookeeper</artifactId>      <version>3.4.6</version></dependency>

 

2、创建zookeeper连接

  ZooKeeper(java.lang.String connectString, int sessionTimeout, org.apache.zookeeper.Watcher watcher) 

    • connectString:zookeeper服务地址,例如“192.168.117.128:2181”
    • sessionTimeout :超时时间,单位为毫秒
    • watcher:实现org.apache.zookeeper.Watcher接口的实现类,需实现process(WatchedEvent watchedEvent) 方法

  ZooKeeper zooKeeper = new ZooKeeper("192.168.117.128:2181",5000, new MyWatcher());

示例代码:

import org.apache.zookeeper.WatchedEvent;import org.apache.zookeeper.Watcher;import org.apache.zookeeper.ZooKeeper;import java.io.IOException;/** * * zookeeper连接 */public class CreateSession implements Watcher{  private static ZooKeeper zooKeeper;  @Override  public void process(WatchedEvent watchedEvent) {    if(watchedEvent.getState().equals(Event.KeeperState.SyncConnected)) {      doBus();    }    System.out.println("接收内容:"+watchedEvent.toString());  }  private void doBus() {    System.out.println("做业务!");  }  public static void main(String[] args) {    try {      zooKeeper = new ZooKeeper("192.168.117.128:2181",5000, new CreateSession());      System.out.println(zooKeeper.getState());      Thread.sleep(5000);    } catch (IOException e) {      e.printStackTrace();    } catch (InterruptedException e) {      e.printStackTrace();    }  }}

  ps:此处没有新创建新的java类实现Watcher,而是直接在本类中实现Watcher接口并重写process方法

 

3、同步创建

  create(java.lang.String path, byte[] data, java.util.List<org.apache.zookeeper.data.ACL> acl, org.apache.zookeeper.CreateMode createMode)

    • path:创建节点路径,需保证父节点已存在
    • data:节点数据
    • acl:权限列表
      • 提供默认的权限OPEN_ACL_UNSAFE、CREATOR_ALL_ACL、READ_ACL_UNSAFE
        • OPEN_ACL_UNSAFE:完全开放
        • CREATOR_ALL_ACL:创建该znode的连接拥有所有权限
        • READ_ACL_UNSAFE:所有的客户端都可读
      • 自定义权限  
        ACL aclIp = new ACL(ZooDefs.Perms.READ,new Id("ip","127.0.0.1"));        ACL aclDigest = new ACL(ZooDefs.Perms.READ| ZooDefs.Perms.WRITE,            new Id("digest", DigestAuthenticationProvider.generateDigest("id:pass")));

      • session设置权限 
        zk.addAuthInfo("digest", "id:pass".getBytes());  
    • createMode:节点类型
      • PERSISTENT:持久化节点
      • PERSISTENT_SEQUENTIAL:持久化有序节点
      • EPHEMERAL:临时节点(连接断开自动删除)
      • EPHEMERAL_SEQUENTIAL:临时有序节点(连接断开自动删除)

示例代码:  

import org.apache.zookeeper.*;import org.apache.zookeeper.data.ACL;import org.apache.zookeeper.data.Id;import org.apache.zookeeper.server.auth.DigestAuthenticationProvider;import java.io.IOException;import java.security.NoSuchAlgorithmException;/** * 创建节点(同步) * Created by scot on 2016/6/8. */public class CreateSessionSync implements Watcher{  private static ZooKeeper zooKeeper;  @Override  public void process(WatchedEvent watchedEvent) {    if(watchedEvent.getState().equals(Event.KeeperState.SyncConnected)) {      doBus();    }    System.out.println("接收内容:"+watchedEvent.toString());  }  private void doBus() {    try {      if(null != zooKeeper.exists("/note_scot/note_scot_a",false)) {        System.out.println("/note_scot/note_scot_a 节点已存在");        return;      }      String path = zooKeeper.create("/note_scot/note_scot_a","aa".getBytes(),          ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);      /*权限相关      try {        ACL aclIp = new ACL(ZooDefs.Perms.READ,new Id("ip","127.0.0.1"));        ACL aclDigest = new ACL(ZooDefs.Perms.READ| ZooDefs.Perms.WRITE,            new Id("digest", DigestAuthenticationProvider.generateDigest("id:pass")));        zooKeeper.addAuthInfo("digest", "id:pass".getBytes());       } catch (NoSuchAlgorithmException e) {        e.printStackTrace();      }*/      System.out.println("zookeeper return:" + path);    } catch (KeeperException e) {      e.printStackTrace();    } catch (InterruptedException e) {      e.printStackTrace();    }  }  public static void main(String[] args) {    try {      zooKeeper = new ZooKeeper("192.168.117.128:2181",5000, new CreateSessionSync());      System.out.println(zooKeeper.getState());      Thread.sleep(5000);    } catch (IOException e) {      e.printStackTrace();    } catch (InterruptedException e) {      e.printStackTrace();    }  }}

 

4、异步创建

  create(java.lang.String path, byte[] data, java.util.List<org.apache.zookeeper.data.ACL> acl,

      org.apache.zookeeper.CreateMode createMode, org.apache.zookeeper.AsyncCallback.StringCallback cb, java.lang.Object ctx) 

    • StringCallback cb:回调接口,执行创建操作后,结果以及数据发送到此接口的实现类中
    • Object ctx:自定义回调数据,在回调实现类可以获取此数据

示例代码:

import org.apache.zookeeper.*;import java.io.IOException;/** * 创建节点(异步) * Created by scot on 2016/6/8. */public class CreateSessionASync implements Watcher{  private static ZooKeeper zooKeeper;  @Override  public void process(WatchedEvent watchedEvent) {    if(watchedEvent.getState().equals(Event.KeeperState.SyncConnected)) {      doBus();    }    System.out.println("接收内容:"+watchedEvent.toString());  }  private void doBus() {      zooKeeper.create("/note_scot/note_scot_b","aa".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE,          CreateMode.PERSISTENT_SEQUENTIAL,new IStringCallBack(),"testAsync");  }  public static void main(String[] args) {    try {      zooKeeper = new ZooKeeper("192.168.117.128:2181",5000, new CreateSessionASync());      System.out.println(zooKeeper.getState());      Thread.sleep(5000);    } catch (IOException e) {      e.printStackTrace();    } catch (InterruptedException e) {      e.printStackTrace();    }  }  static class IStringCallBack implements AsyncCallback.StringCallback {    @Override    public void processResult(int i, String s, Object o, String s2) {      System.out.println("i="+i);//创建成功返回0      System.out.println("s="+s);//自定义节点名称      System.out.println("o="+o);//自定义回调数据      System.out.println("s2="+s2);//最终节点名称(顺序节点最终名称与自定义名称不同)    }  }}