zookeeper

启动zk客户端

>.\zkCli.cmd

指定host和port：

>zkCli.cmd -server localhost:2191

 

connect

格式：

connect host:port

例子：

connect localhost 2181

 

acl

ACLs是由scheme:expression和perms组成的(scheme:expression, perms)，其中scheme:expression是Ids。

Ids格式：

scheme:id

 

acl格式：scheme:id:perm

其中

scheme:id表示Ids

perm用于指定权限，支持CREATE、READ、WRITE、DELETE以及ADMIN：

CREATE: you can create a child node

READ: you can get data from a node and list its children.

WRITE: you can set data for a node

DELETE: you can delete a child node

 

ADMIN: you can set permissions

 

acl支持4种scheme：world、auth、digest以及ip：

world has a single id, anyone, that represents anyone.

auth doesn't use any id, represents any authenticated user.

digest uses a username:password string to generate MD5 hash which is then used as an ACL ID identity. Authentication is done by sending the username:password in clear text. When used in the ACL the expression will be the username:base64 encoded SHA1 password digest.

ip uses the client host IP as an ACL ID identity. The ACL expression is of the form addr/bits where the most significant bits of addr are matched against the most significant bits of the client host IP.

 

设置ACL

格式：

setAcl path acl

例子：

setAcl /test1 world:anyone:cdrw

 

获取ACL

格式：

getAcl path

例子：

getAcl /test1

'world,'anyone

: cdrwa

 

如果scheme指定world，id只能是anyone，表示任何人都有对应的权限。

例如：

create /test1 'test data'

 

getAcl /test1

'world,'anyone

: cdrwa

 

setAcl /test1 world:anyone:cdrw

 

getAcl /test1

'world,'anyone

: cdrw

 

由于上面已经收回了ADMIN: you can set permissions的权限，所以要是在设置acl话报Authentication is not valid : /test1的错误：

setAcl /test1 world:anyone:cdrw

Authentication is not valid : /test1

 

如果scheme指定auth，则不需要指定id，表示任何认证的用户都有对应的权限。

例如：

create /test2 'test data'

 

getAcl /test2

'world,'anyone

: cdrwa

 

在设置acl时，如果scheme指定auth，需要先通过addauth命令添加认证用户：

addauth digest user1:pwd1

setAcl /test2 auth::cdrwa

 

addauth digest user2:pwd2

setAcl /test2 auth::cdrwa

 

这样写没有报错，但不会生效：

setAcl /test2 auth:user3:pwd3:cdrwa

 

addauth digest user4:pwd4

setAcl /test2 auth::cdrwa

 

getAcl /test2

'digest,'user1:a9l5yfb9zl8WCXjVmi5/XOC0Ep4=

: cdrwa

这里的user1:a9l5yfb9zl8WCXjVmi5/XOC0Ep4=就是上面添加的认证用户user1:pwd1。

 

public interface Perms {
    int READ = 1 << 0;

    int WRITE = 1 << 1;

    int CREATE = 1 << 2;

    int DELETE = 1 << 3;

    int ADMIN = 1 << 4;

    int ALL = READ | WRITE | CREATE | DELETE | ADMIN;
}

 

public interface Ids {
    /**
     * This Id represents anyone.
     */
    public final Id ANYONE_ID_UNSAFE = new Id("world", "anyone");

    /**
     * This Id is only usable to set ACLs. It will get substituted with the
     * Id's the client authenticated with.
     */
    public final Id AUTH_IDS = new Id("auth", "");

    /**
     * This is a completely open ACL .
     */
    public final ArrayList<ACL> OPEN_ACL_UNSAFE = new ArrayList<ACL>(
	Collections.singletonList(new ACL(Perms.ALL, ANYONE_ID_UNSAFE)));

    /**
     * This ACL gives the creators authentication id's all permissions.
     */
    public final ArrayList<ACL> CREATOR_ALL_ACL = new ArrayList<ACL>(
	Collections.singletonList(new ACL(Perms.ALL, AUTH_IDS)));

    /**
     * This ACL gives the world the ability to read.
     */
    public final ArrayList<ACL> READ_ACL_UNSAFE = new ArrayList<ACL>(
	Collections
		.singletonList(new ACL(Perms.READ, ANYONE_ID_UNSAFE)));
}

 

 

import org.apache.zookeeper.*;
import org.apache.zookeeper.data.ACL;
import org.apache.zookeeper.data.Stat;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;

public class ZookeeperSession implements Watcher {

    private ZooKeeper zk;

    public boolean closed;

    public ZookeeperSession(String connectionString) throws ZookeeperException {
        try {
            zk = new ZooKeeper(connectionString, 3000, this);
        } catch (IOException e) {
            throw new ZookeeperException(e);
        }
    }

    public boolean exists(String path) throws ZookeeperException {
        return exists(path, false);
    }

    public boolean exists(String path, boolean watch) throws ZookeeperException {
        Stat stat = null;
        try {
            stat = zk.exists(path, watch);
        } catch (KeeperException e) {
            throw new ZookeeperException(e);
        } catch (InterruptedException e) {
            throw new ZookeeperException(e);
        }
        return stat != null;
    }

    public boolean exists(final String path, Watcher watcher) throws ZookeeperException {
        Stat stat = null;
        try {
            stat = zk.exists(path, watcher);
        } catch (KeeperException e) {
            throw new ZookeeperException(e);
        } catch (InterruptedException e) {
            throw new ZookeeperException(e);
        }
        return stat != null;
    }

    public void exists(String path, boolean watch, AsyncCallback.StatCallback cb, Object ctx) {
        zk.exists(path, watch, cb, ctx);
    }

    public void exists(final String path, Watcher watcher, AsyncCallback.StatCallback cb, Object ctx) {
        zk.exists(path, watcher, cb, ctx);
    }

    /**
     * The maximum allowable size of the data array is 1 MB (1,048,576 bytes).
     * Arrays larger than this will cause a KeeperExecption to be thrown.
     *
     * @param path
     * @param data
     * @return
     * @throws ZookeeperException
     */
    public String create(String path, byte data[]) throws ZookeeperException {
        return create(path, data, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
    }

    public String create(final String path, byte data[], List<ACL> acl, CreateMode createMode) throws ZookeeperException {
        try {
            return zk.create(path, data, acl, createMode);
        } catch (KeeperException e) {
            throw new ZookeeperException(e);
        } catch (InterruptedException e) {
            throw new ZookeeperException(e);
        }
    }

    /**
     * whether the session to zookeeper is opened or closed. if the
     * session is current closed, then the current session is close,
     * this is no question. but if the session current is not close,
     * this not indicates the session current is normal open state.
     * @return
     */
    public boolean isClose() {
        return false;
    }

    @Override
    public void process(WatchedEvent e) {
        Event.EventType type = e.getType();
        System.out.println("event Event(" + type + ") received.");

        Event.KeeperState state = e.getState();
        System.out.println("zk current state " + state + ", on Event(" + type + ")");
        if (type == Event.EventType.None) {
            switch (state) {
                case SyncConnected:
                    closed = false;
                    break;
                case Expired:
                    closed = true;
                    break;
            }
        }
    }
}

 

import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.data.ACL;

import java.util.List;

public class ZookeeperClient {

    private String connectionString;

    public ZookeeperClient(String connectionString) {
        this.connectionString = connectionString;
    }

    public ZookeeperSession getSession() throws ZookeeperException {
        return new ZookeeperSession(connectionString);
    }

    public boolean exists(String path) throws ZookeeperException {
        ZookeeperSession session = getSession();
        return session.exists(path);
    }

    public boolean exists(String path, boolean watch) throws ZookeeperException {
        ZookeeperSession session = getSession();
        return session.exists(path, watch);
    }

    public boolean exists(final String path, Watcher watcher) throws ZookeeperException {
        ZookeeperSession session = getSession();
        return session.exists(path, watcher);
    }

    public String create(String path, byte data[]) throws ZookeeperException {
        ZookeeperSession session = getSession();
        return session.create(path, data);
    }

    public String create(final String path, byte data[], List<ACL> acl, CreateMode createMode) throws ZookeeperException {
        ZookeeperSession session = getSession();
        return session.create(path, data, acl, createMode);
    }
}

 

1、zookeeper中的消息结构: https://lobin.iteye.com/blog/2384664

2、zookeeper快照（Snapshot）文件结构：https://lobin.iteye.com/blog/2384782

3、zookeeper事务日志文件结构：https://lobin.iteye.com/blog/2386346