Curator框架的使用

 

Curator框架使用鏈式編程風格，易讀性更強，使用工廠方法創建連接對象。

1.使用CuratorFrameworkFactory的兩個靜態工廠方法（參數不同）來實現

參數1：connectString，連接信息

參數2：RetryPolicy，重試連接策略，有四種實現

　　ExponentialBackoffRetry、RetryNTimes、RetryOneTimes、RetryUntilElapsed

參數3：sessionTimeoutMs會話超時時間，默認為60s

參數4：connectionTimeoutMs連接超時時間，默認為15s

注意：對於retryPolicy策略通過一個接口來讓用戶自定義實現

 

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 = "192.168.1.171:2181,192.168.1.172:2181,192.168.1.173:2181";
    /** session超時時間 */
    static final int SESSION_OUTTIME = 5000;//ms 
    
    public static void main(String[] args) throws Exception {
        
        //1 重試策略：初試時間為1s 重試10次
        RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 10);
        //2 通過工廠創建連接
        CuratorFramework cf = CuratorFrameworkFactory.builder()
                    .connectString(CONNECT_ADDR)
                    .sessionTimeoutMs(SESSION_OUTTIME)
                    .retryPolicy(retryPolicy)
//                    .namespace("super")
                    .build();
        //3 開啟連接
        cf.start();
        
//        System.out.println(States.CONNECTED);
//        System.out.println(cf.getState());
        
        // 新加、刪除
        /**
        //4 建立節點 指定節點類型（不加withMode默認為持久類型節點）、路徑、數據內容
        cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath("/super/c1","c1內容".getBytes());
        //5 刪除節點
        cf.delete().guaranteed().deletingChildrenIfNeeded().forPath("/super");
        */
        
        // 讀取、修改
        /**
        //創建節點
//        cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath("/super/c1","c1內容".getBytes());
//        cf.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath("/super/c2","c2內容".getBytes());
        //讀取節點
//        String ret1 = new String(cf.getData().forPath("/super/c2"));
//        System.out.println(ret1);
        //修改節點
//        cf.setData().forPath("/super/c2", "修改c2內容".getBytes());
//        String ret2 = new String(cf.getData().forPath("/super/c2"));
//        System.out.println(ret2);    
        */
        
        // 綁定回調函數
        /**
        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("線程為:" + Thread.currentThread().getName());
            }
        }, pool)
        .forPath("/super/c3","c3內容".getBytes());
        Thread.sleep(Integer.MAX_VALUE);
        */
        
        
        // 讀取子節點getChildren方法 和 判斷節點是否存在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");
        
    }
}