JAVA线程的高级同步[5]

    public Semaphore(long permits, boolean fair);

    public void acquire( ) throws InterruptedException;

    public void acquireUninterruptibly( );

    public void acquire(long permits) throws InterruptedException;

    public void acquireUninterruptibly(long permits);

    public boolean tryAcquire( );

    public boolean tryAcquire(long timeout, TimeUnit unit);

    public boolean tryAcquire(long permits);