Java trere是使用带有锁的concurrentmap的更简单的方法吗？

我有一个要求，每个实体ID中的某些函数中都有锁

private final ConcurrentMap<Long, Lock> idLocks = Maps.newConcurrentMap();

public void doSmth(Long id){
    ReentrantLock newLock = new ReentrantLock();
    Lock lock = prLocks.putIfAbsent( id, newLock ); //returns null for first run for this id
    if (null == lock) { //have to do null checking 
        lock = newLock;
    }
    if (lock.tryLock()){
        try {
        //some code here
        } finally {
            lock.unlock();
        }
    }
}

private final ConcurrentMap idLocks=Maps.newConcurrentMap（）；
公共无效doSmth（长id）{
ReentrantLock newLock=新的ReentrantLock（）；
Lock Lock=prLocks.putIfAbsent（id，newLock）；//此id的第一次运行返回null
如果（null==lock）{//必须执行null检查
lock=newLock；
}
if（lock.tryLock（））{
试一试{
//这里有一些代码
}最后{
lock.unlock（）；
}
}
}

---

是否有方法运行

Lock Lock=returnExistingOrPutAndReturnNew（id，newLock）

要消除空检查？

否，ConcurrentMap中没有此类方法，但您可以使用：

似乎是的

private final LoadingCache<Long, Lock> idLocks = CacheBuilder.newBuilder()
       .build(
             new CacheLoader<Long, Lock>() {
                   public Lock load(Long id) throws AnyException {
                       return new ReentrantLock();
                   }
             });

public void doSmth(Long id){
     Lock lock = prLocks.get(id); //always return not-null Lock
     if (lock.tryLock()){
          try {
             //some code here
          } finally {
             lock.unlock();
          }
     }
 }

public void doSmth(Long id){
    Lock lock = prLocks.computeIfAbsent(id, key -> new ReentrantLock());
    if (lock.tryLock()){
        try {
            //some code here
        } finally {
            lock.unlock();
        }
    }
}