轉載自https://www.cnblogs.com/zhangjunqing/p/7823626.html

基礎知識：http://www.cnblogs.com/LiZhiW/p/4931577.html

專案路徑：https://gitee.com/zhangjunqing/spring-boot

1 可重入讀寫鎖示例程式碼如下（lock.acquire加幾個，就必須使用幾個lock.release()釋放）：

package com.topsec.lock;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.locks.InterProcessMutex;
import org.apache.curator.retry.ExponentialBackoffRetry;

/**
 * 測試可重入鎖（可以多次獲得鎖不會被阻塞，釋放時也需釋放多把鎖）
 * @author 76524
 *
 */
public class SharedReentrantLock1  implements Runnable{
    private InterProcessMutex lock;//可重入鎖實現類
    private String lockPAth = "/lock/shareLock";
    private int i;
    private String clientName;
    //zookeeper叢集地址
    public static final String ZOOKEEPERSTRING = "192.168.99.129:2181,192.168.99.153:2181,192.168.99.171:2181";
    
    public SharedReentrantLock1(CuratorFramework client,String clientName) {
        lock = new InterProcessMutex(client, lockPAth);
        this.clientName = clientName;
    }
    
    public void run() {
        try {
            Thread.sleep((new java.util.Random().nextInt(2000)));
            lock.acquire();  //增加第一把鎖
            if(lock.isAcquiredInThisProcess()) {
                System.out.println(clientName + " 獲得鎖");
                i++;
            }
            lock.acquire();  //增加第二把鎖
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            try {
                
                System.out.println(clientName+"釋放第一把鎖");
                lock.release();
                System.out.println(clientName+"釋放第二把鎖");
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        
    }
    
    public static void main(String[] args) {
        CuratorFramework client = CuratorFrameworkFactory.newClient(ZOOKEEPERSTRING, new ExponentialBackoffRetry(1000, 3));
        client.start();
        //啟動100個執行緒進行測試
        for(int i = 0;i<100;i++) {
            SharedReentrantLock1 sharedReentrantLock = new SharedReentrantLock1(client, "第"+i+"個客戶端：");
            Thread thread = new Thread(sharedReentrantLock);
            thread.start();
        }
    }
    
}
 

package com.topsec.lock;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.locks.InterProcessSemaphoreMutex;
import org.apache.curator.retry.ExponentialBackoffRetry;
/**
 * 測試不可重入鎖（只能獲得一次鎖，使用完後釋放）
 * @author 76524
 *
 */
public class SharedNOReentrantLock   implements Runnable{
    private InterProcessSemaphoreMutex lock;//不可重入鎖
    private String lockPAth = "/lock/shareLock";
    private int i;
    private String clientName;
    //zookeeper叢集地址
    public static final String ZOOKEEPERSTRING = "192.168.99.129:2181,192.168.99.153:2181,192.168.99.171:2181";
    
    public SharedNOReentrantLock(CuratorFramework client,String clientName) {
        lock = new InterProcessSemaphoreMutex(client, lockPAth);
        this.clientName = clientName;
    }
    
    public void run() {
        try {
            Thread.sleep((new java.util.Random().nextInt(2000)));
            lock.acquire();  //增加第一把鎖
            if(lock.isAcquiredInThisProcess()) {
                System.out.println(clientName + " 獲得鎖");
                i++;
            }
            lock.acquire();  //增加第二把鎖這個鎖相當於不起作用
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            try {
//                lock.release();
                System.out.println(clientName+"釋放第一把鎖");
                lock.release();
                System.out.println(clientName+"釋放第二把鎖");
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        
    }
    
    public static void main(String[] args) {
        CuratorFramework client = CuratorFrameworkFactory.newClient(ZOOKEEPERSTRING, new ExponentialBackoffRetry(1000, 3));
        client.start();
        for(int i = 0;i<100;i++) {
            SharedReentrantLock2 sharedReentrantLock = new SharedReentrantLock2(client, "第"+i+"個客戶端：");
            Thread thread = new Thread(sharedReentrantLock);
            thread.start();
        }
    }
    
}
 

ps:最後的基於訊號量的不可重入鎖，看其構造方法其實maxLeases的值設定為1，這樣每次只能有一個獲取到鎖，其他等待其釋放lease後才能獲取到鎖。