(原) 2.1 Zookeeper原生API使用
2016-06-23 22:23
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本文为原创文章,转载请注明出处,谢谢
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) } } }
常用方法列表:
String create(final String path, byte data[], List acl, CreateMode createMode) | 参数: 路径、 znode内容,ACL(访问控制列表)、 znode创建类型; 用途:创建znode节点 |
void delete(final String path, int version) | 参数: 路径、版本号;如果版本号与znode的版本号不一致,将无法删除,是一种乐观加锁机制;如果将版本号设置为-1,不会去检测版本,直接删除; 用途:删除节点 |
Stat exists(final String path, Watcher watcher) | 参数: 路径、Watcher(监视器);当这个znode节点被改变时,将会触发当前Watcher 用途:判断znode节点是否存在 |
Stat exists(String path, boolean watch) | 参数: 路径、并设置是否监控这个目录节点,这里的 watcher 是在创建 ZooKeeper 实例时指定的 watcher; 判断znode节点是否存在 |
Stat setData(final String path, byte data[], int version) | 参数: 路径、数据、版本号;如果为-1,跳过版本检查 用途:设置znode上的数据 |
byte[] getData(final String path, Watcher watcher, Stat stat) | 参数: 路径、监视器、数据版本等信息 用途:获取znode上的数据 |
List getChildren(final String path, Watcher watcher) | 参数: 路径、监视器;该方法有多个重载 用途:获取节点下的所有子节点 |
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