你作为一个Java领域的专家,请完成以下任务:zookeeper实现分布式锁
时间: 2023-11-28 13:51:15 浏览: 28
好的,下面是使用Zookeeper实现分布式锁的Java代码:
```java
import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.CountDownLatch;
public class DistributedLock {
private ZooKeeper zk;
private String lockPath;
private String lockName;
private String lockNode;
private CountDownLatch latch = new CountDownLatch(1);
public DistributedLock(String zkServer, String lockPath, String lockName) throws Exception {
this.lockPath = lockPath;
this.lockName = lockName;
this.zk = new ZooKeeper(zkServer, 3000, new Watcher() {
@Override
public void process(WatchedEvent event) {
if (event.getType() == Event.EventType.None) {
if (event.getState() == Event.KeeperState.SyncConnected) {
latch.countDown();
}
}
}
});
latch.await();
Stat stat = zk.exists(lockPath, false);
if (stat == null) {
zk.create(lockPath, "".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}
}
public void lock() throws Exception {
lockNode = zk.create(lockPath + "/" + lockName + "-", "".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
while (true) {
List<String> nodes = zk.getChildren(lockPath, false);
Collections.sort(nodes);
int index = nodes.indexOf(lockNode.substring(lockNode.lastIndexOf("/") + 1));
if (index == 0) {
return;
} else {
String watchNode = nodes.get(index - 1);
Stat stat = zk.exists(lockPath + "/" + watchNode, new Watcher() {
@Override
public void process(WatchedEvent event) {
synchronized (this) {
notifyAll();
}
}
});
if (stat != null) {
synchronized (this) {
wait();
}
}
}
}
}
public void unlock() throws Exception {
zk.delete(lockNode, -1);
}
}
```
使用方法如下:
```java
public static void main(String[] args) throws Exception {
String zkServer = "localhost:2181";
String lockPath = "/mylock";
String lockName = "test";
DistributedLock lock = new DistributedLock(zkServer, lockPath, lockName);
lock.lock();
try {
// do something
} finally {
lock.unlock();
}
}
```
上面的代码使用了ZooKeeper的临时顺序节点实现了分布式锁。当多个进程需要获取锁时,它们会在ZooKeeper上创建临时顺序节点,并按照节点名称的顺序进行排序。排在最前面的那个进程获得锁,其他进程则需要等待前面的进程释放锁。释放锁时,进程会删除自己创建的临时节点。这种方式可以保证只有一个进程获得锁,其他进程都在等待。