Skip to main content
 首页 » 编程设计

zk分布式锁-排它锁简单实现-优化版

2022年07月18日22lyj

package Lock;

import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;

import org.I0Itec.zkclient.IZkChildListener;
import org.I0Itec.zkclient.IZkDataListener;
import org.I0Itec.zkclient.ZkClient;

public class ImproveLock implements Lock{
private static String ZK_IP_PORT= "192.168.0.137:2181";
private static String LOCK_NODE = "/lock";
private ZkClient client = new ZkClient(ZK_IP_PORT);
private String currentNode = null; //当前节点
private String beforeNode = null; //前一个节点
private CountDownLatch cdl = null;

public ImproveLock(){
//创建持久节点
if(!client.exists(LOCK_NODE)){
client.createPersistent(LOCK_NODE);
}
}

@Override
public void lock() {
if(tryLock()){
return ;
}
waitForLock();
lock();
}

private void waitForLock(){
IZkDataListener listener = new IZkDataListener() {

@Override
public void handleDataDeleted(String dataPath) throws Exception {
if(cdl != null){
cdl.countDown();
}
}

@Override
public void handleDataChange(String dataPath, Object data) throws Exception {

}
};

client.subscribeDataChanges(beforeNode, listener);
if(client.exists(beforeNode)){
cdl = new CountDownLatch(1);
try {
cdl.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
client.unsubscribeDataChanges(beforeNode, listener);
}

@Override
public void lockInterruptibly() throws InterruptedException {

}
@Override
public boolean tryLock() {
if(currentNode == null || currentNode.length() == 0){
currentNode = client.createEphemeralSequential(LOCK_NODE + "/", "lock");
System.out.println("--------------:" + currentNode);
}
//获取所有的子节点
List<String> children = client.getChildren(LOCK_NODE);
//子节点排序
Collections.sort(children);
if(currentNode.equals(LOCK_NODE + "/" + children.get(0))){
return true;
}
//找当前节点的前一个节点
int index = Collections.binarySearch(children, currentNode.substring(6));
if(index > 0){
index = index - 1;
}
beforeNode = LOCK_NODE + "/" + children.get(index);
return false;
}
@Override
public boolean tryLock(long time, TimeUnit unit) throws InterruptedException {
return false;
}
@Override
public void unlock() {
client.delete(currentNode);
}
@Override
public Condition newCondition() {
return null;
}
}

---------------------test-----

package Lock;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.CountDownLatch;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class LockTest {
private static Logger LOG = LoggerFactory.getLogger(LockTest.class);
private static int count = 10;
private static CountDownLatch cdl = new CountDownLatch(count);
public static void main(String[] args) {
for(int i = 0; i < count;i++){
new Thread(new Order()).start();
LOG.error("开启");
cdl.countDown();
}
}

static class Order implements Runnable{
//private DistributeLock lock = new DistributeLock();
private ImproveLock lock = new ImproveLock();
@Override
public void run() {
try {
cdl.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
lock.lock();
String orderId = GenorderId.genOrderId();

System.out.println(orderId);
lock.unlock();
}

}

static class GenorderId{
private static int index = 0;
public static String genOrderId(){
SimpleDateFormat sdf = new SimpleDateFormat("yyyymmddhhmmss|SSS");
return sdf.format(new Date()) + ++index;
}
}

}


本文参考链接:https://www.cnblogs.com/maohuidong/p/8433611.html