简介
Curator是Netflix开源的一套ZooKeeper客户端框架. Netflix在使用ZooKeeper的过程中发现ZooKeeper自带的客户端太底层, 应用方在使用的时候需要自己处理很多事情, 于是在它的基础上包装了一下, 提供了一套更好用的客户端框架。
1、zookekeeper基本功能
连接zookeeper,对节点进行crud、回调函数、判断节点是否存在
package bjsxt.curator.base; import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors; import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.api.BackgroundCallback;
import org.apache.curator.framework.api.CuratorEvent;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.ZooKeeper.States;
import org.apache.zookeeper.data.Stat; public class CuratorBase { /** zookeeper地址 */
static final String CONNECT_ADDR = "192.168.0.4:2181,192.168.0.9:2181,192.168.0.6:2181";
/** session超时时间 */
static final int SESSION_OUTTIME = 5000;//ms public static void main(String[] args) throws Exception { //1 重试策略:初试时间为1s 重试10次
RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 10);
//2 通过工厂创建连接
CuratorFramework cf = CuratorFrameworkFactory.builder()
.connectString(CONNECT_ADDR)
.sessionTimeoutMs(SESSION_OUTTIME)
.retryPolicy(retryPolicy)
// .namespace("super")
.build();
//3 开启连接
cf.start(); System.out.println(States.CONNECTED);
System.out.println(cf.getState()); // 新加、删除 //4 建立节点 指定节点类型(不加withMode默认为持久类型节点)、路径、数据内容
//cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath("/super/c1","c1内容".getBytes());
//5 删除节点
// cf.delete().guaranteed().deletingChildrenIfNeeded().forPath("/super"); // 读取、修改 //创建节点
/* cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath("/super/c1","c1内容".getBytes());
cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath("/super/c2","c2内容".getBytes());
//读取节点
String ret1 = new String(cf.getData().forPath("/super/c2"));
System.out.println("修改前c2节点====="+ret1);
//修改节点
cf.setData().forPath("/super/c2", "修改c2内容".getBytes());
String ret2 = new String(cf.getData().forPath("/super/c2"));
System.out.println("修改后c2节点====="+ret2);*/ // 绑定回调函数 ExecutorService pool = Executors.newCachedThreadPool();
cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT)
.inBackground(new BackgroundCallback() {
@Override
public void processResult(CuratorFramework cf, CuratorEvent ce) throws Exception {
System.out.println("code:" + ce.getResultCode());
System.out.println("type:" + ce.getType());
System.out.println("线程为:" + Thread.currentThread().getName());
}
}, pool)
.forPath("/super/c3","c3内容".getBytes());
Thread.sleep(Integer.MAX_VALUE); // 读取子节点getChildren方法 和 判断节点是否存在checkExists方法
/**
List<String> list = cf.getChildren().forPath("/super");
for(String p : list){
System.out.println(p);
} Stat stat = cf.checkExists().forPath("/super/c3");
System.out.println(stat); Thread.sleep(2000);
cf.delete().guaranteed().deletingChildrenIfNeeded().forPath("/super");
*/ //cf.delete().guaranteed().deletingChildrenIfNeeded().forPath("/super");
cf.close();
}
}
2、watcher方式一(监听当前节点发生变更)
package bjsxt.curator.watcher; import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.framework.recipes.cache.NodeCache;
import org.apache.curator.framework.recipes.cache.NodeCacheListener;
import org.apache.curator.retry.ExponentialBackoffRetry; public class CuratorWatcher1 { /** zookeeper地址 */
static final String CONNECT_ADDR = "192.168.0.4:2181,192.168.0.9:2181,192.168.0.6:2181";
/** session超时时间 */
static final int SESSION_OUTTIME = 5000;//ms public static void main(String[] args) throws Exception { //1 重试策略:初试时间为1s 重试10次
RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 10);
//2 通过工厂创建连接
CuratorFramework cf = CuratorFrameworkFactory.builder()
.connectString(CONNECT_ADDR)
.sessionTimeoutMs(SESSION_OUTTIME)
.retryPolicy(retryPolicy)
.build(); //3 建立连接
cf.start(); //4 建立一个cache缓存
final NodeCache cache = new NodeCache(cf, "/super", false);
cache.start(true);
cache.getListenable().addListener(new NodeCacheListener() {
/**
* <B>方法名称:</B>nodeChanged<BR>
* <B>概要说明:</B>触发事件为创建节点和更新节点,在删除节点的时候并不触发此操作。<BR>
* @see org.apache.curator.framework.recipes.cache.NodeCacheListener#nodeChanged()
*/
@Override
public void nodeChanged() throws Exception {
System.out.println("监听节点路径=====" + cache.getCurrentData().getPath());
System.out.println("数据=====" + new String(cache.getCurrentData().getData()));
System.out.println("状态=====" + cache.getCurrentData().getStat());
System.out.println("---------------------------------------");
}
}); Thread.sleep(1000);
cf.create().forPath("/super", "123".getBytes()); Thread.sleep(1000);
cf.setData().forPath("/super", "456".getBytes()); Thread.sleep(1000);
cf.delete().forPath("/super"); Thread.sleep(Integer.MAX_VALUE); }
}
3、watcher方式二(监听当前节点的子节点发生变更)
package bjsxt.curator.watcher; import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.cache.PathChildrenCache;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheListener;
import org.apache.curator.framework.recipes.cache.PathChildrenCache.StartMode;
import org.apache.curator.retry.ExponentialBackoffRetry; public class CuratorWatcher2 { /** zookeeper地址 */
static final String CONNECT_ADDR = "192.168.0.4:2181,192.168.0.9:2181,192.168.0.6:2181";
/** session超时时间 */
static final int SESSION_OUTTIME = 5000;//ms public static void main(String[] args) throws Exception { //1 重试策略:初试时间为1s 重试10次
RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 10);
//2 通过工厂创建连接
CuratorFramework cf = CuratorFrameworkFactory.builder()
.connectString(CONNECT_ADDR)
.sessionTimeoutMs(SESSION_OUTTIME)
.retryPolicy(retryPolicy)
.build(); //3 建立连接
cf.start(); //4 建立一个PathChildrenCache缓存,第三个参数为是否接受节点数据内容 如果为false则不接受
PathChildrenCache cache = new PathChildrenCache(cf, "/super", true);
//5 在初始化的时候就进行缓存监听
cache.start(StartMode.POST_INITIALIZED_EVENT);
cache.getListenable().addListener(new PathChildrenCacheListener() {
/**
* <B>方法名称:</B>监听子节点变更<BR>
* <B>概要说明:</B>新建、修改、删除<BR>
* @see org.apache.curator.framework.recipes.cache.PathChildrenCacheListener#childEvent(org.apache.curator.framework.CuratorFramework, org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent)
*/
@Override
public void childEvent(CuratorFramework cf, PathChildrenCacheEvent event) throws Exception {
switch (event.getType()) {
case CHILD_ADDED:
System.out.println("新增子节点 =====" + event.getData().getPath());
break;
case CHILD_UPDATED:
System.out.println("修改子节点=====" + event.getData().getPath());
break;
case CHILD_REMOVED:
System.out.println("删除子节点=====" + event.getData().getPath());
break;
default:
break;
}
}
}); //创建本身节点不发生变化
cf.create().forPath("/super", "init".getBytes()); //添加子节点
Thread.sleep(1000);
cf.create().forPath("/super/c1", "c1内容".getBytes());
Thread.sleep(1000);
cf.create().forPath("/super/c2", "c2内容".getBytes()); //修改子节点
Thread.sleep(1000);
cf.setData().forPath("/super/c1", "c1更新内容".getBytes()); //删除子节点
Thread.sleep(1000);
cf.delete().forPath("/super/c2"); //删除本身节点
Thread.sleep(1000);
cf.delete().deletingChildrenIfNeeded().forPath("/super"); Thread.sleep(Integer.MAX_VALUE); }
}