// 支持中斷的API
void lockInterruptibly() throws InterruptedException;
// 支持超時(shí)的API
boolean tryLock(long time, TimeUnit unit)  throws InterruptedException;
// 支持非阻塞獲取鎖的API
boolean tryLock();

//線程加入此條件變量的等待隊(duì)列；類似Object.wait()；使用時(shí)也要放到while循環(huán)體內(nèi)。
java.util.concurrent.locks.Condition#await()
java.util.concurrent.locks.Condition#awaitUninterruptibly()
java.util.concurrent.locks.Condition#awaitNanos()
java.util.concurrent.locks.Condition#await(long, java.util.concurrent.TimeUnit)
java.util.concurrent.locks.Condition#awaitUntil()
//激活此條件變量中的一個(gè)線程;類似Object.notify()
java.util.concurrent.locks.Condition#signal()
//激活此條件變量中的所有線程;類似Object.notifyAll()
java.util.concurrent.locks.Condition#signalAll()

class BoundedBuffer {
 final Lock lock = new ReentrantLock();
 final Condition notFull  = lock.newCondition();
 final Condition notEmpty = lock.newCondition();
 final Object[] items = new Object[100];
 int putptr, takeptr, count;
 public void put(Object x) throws InterruptedException {
   lock.lock();
   try {
     while (count == items.length)
       notFull.await();
     items[putptr] = x;
     if (++putptr == items.length) putptr = 0;
     ++count;
     notEmpty.signal();
   } finally {
     lock.unlock();
   }
 }
 public Object take() throws InterruptedException {
   lock.lock();
   try {
     while (count == 0)
       notEmpty.await();
     Object x = items[takeptr];
     if (++takeptr == items.length) takeptr = 0;
     --count;
     notFull.signal();
     return x;
   } finally {
     lock.unlock();
   }
 }
}

 Lock l = ...;
 l.lock();
 try {
   // access the resource protected by this lock
 } finally {
   l.unlock();
 }

 Lock lock = ...;
 if (lock.tryLock()) {
   try {
     // manipulate protected state
   } finally {
     lock.unlock();
   }
 } else {
   // perform alternative actions
 }

while (XXX)
    condition.await();

 l.lock();
 try {
    ...
    while (XXX)
      condition.await();
    ...
 } finally {
   l.unlock();
 }