zookeeper生成序列號2種方式

依賴zookeeper服務生成分布式一致的序列號兩種方式

package zk.seq;

import com.github.zkclient.IZkChildListener;
import com.github.zkclient.ZkClient;
import org.apache.zookeeper.data.Stat;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
/**

Author : secondriver
*/
public class GenerateSeq {
//提前創建好存儲Seq的"/createSeq"結點 CreateMode.PERSISTENT
 public static final String SEQ_ZNODE = "/seq";
//提前創建好鎖對象的結點"/lock" CreateMode.PERSISTENT
 public static final String LOCK_ZNODE = "/lock";
public static void main(String[] args) {

 final ExecutorService service = Executors.newFixedThreadPool(20);

 for (int i = 0; i < 20; i++) {
     service.execute(new Task2("[Concurrent-" + i + "]"));
 }

 if (!service.isShutdown()) {
     try {
         service.shutdown();
         if (!service.awaitTermination(10, TimeUnit.SECONDS)) {
             service.shutdownNow();
         }
     } catch (InterruptedException e) {
         service.shutdownNow();
         System.out.println(e.getMessage());
     }
 }

}
public static class Task1 implements Runnable {

 private final String taskName;

 public Task1(String taskName) {
     this.taskName = taskName;
 }

 @Override
 public void run() {
     ZkClient zkClient = new ZkClient("192.168.88.153:2181", 3000, 1000);
     Stat stat = zkClient.writeData(SEQ_ZNODE, new byte[0], -1);
     int versionAsSeq = stat.getVersion();
     //versionAsSeq 最終的序列號
     System.out.println(taskName + " obtain seq=" + versionAsSeq);
     zkClient.close();
 }

}
//分布式鎖實現
 public static class Task2 implements Runnable, IZkChildListener {

 private final String taskName;

 private final ZkClient zkClient;

 private final String lockPrefix = "/loc";

 private final String selfZnode;

 public Task2(String taskName) {
     this.taskName = taskName;
     zkClient = new ZkClient("192.168.88.153:2181", 30000, 10000);
     selfZnode = zkClient.createEphemeralSequential(LOCK_ZNODE + lockPrefix, new byte[0]);
 }

 @Override
 public void run() {
     zkClient.subscribeChildChanges(LOCK_ZNODE, this);
     do {
     } while (zkClient.isConnected());
 }



    private void createSeq() {
        Stat stat = new Stat();
        byte[] oldData = zkClient.readData(LOCK_ZNODE, stat);
        byte[] newData = update(oldData);
        zkClient.writeData(LOCK_ZNODE, newData);
        //new String(newData) 最終的序列號
        System.out.println(taskName + selfZnode + " obtain seq=" + new String(newData));
    }

    private byte[] update(byte[] currentData) {
        String s = new String(currentData);
        int d = Integer.parseInt(s);
        d = d + 1;
        s = String.valueOf(d);
        return s.getBytes();
    }

    @Override
    public void handleChildChange(String parentPath, List<String> currentChildren) throws Exception {
        String[] childrensZnode = currentChildren.toArray(new String[currentChildren.size()]);
        Arrays.sort(childrensZnode);
        String minZnode = LOCK_ZNODE + "/" + childrensZnode[0];
        if (selfZnode.equals(minZnode)) {
            createSeq();
            zkClient.unsubscribeChildChanges(LOCK_ZNODE, this);
            zkClient.delete(selfZnode);
            zkClient.close();
        }
    }
}

}</pre>