Java NIO - Condition

Condition用来实现对应Object的wati，notify，notifyAll三个方法。

在Condition中用await()替换wait()，用signal()替换notify() ，用signalAll()替换notifyAll()，传统线程之间的通讯Condition都可以实现。如下列子，我们实现一个读写操作，分为读写线程。

package chp3.condition;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class BufferThread {
final Lock lock = new ReentrantLock();// 锁
final Condition notFull = lock.newCondition();// 写线程条件
final Condition notEmpty = lock.newCondition();// 读线程条件
final Object[] items = new Object[10];// 缓存队列
int putptr/* 写索引 */, takeptr/* 读索引 */, count/* 队列中存在的数据个数 */;
public void put(Object x) throws InterruptedException {
lock.lock();
try {
while (count == items.length) {
notFull.await();// 阻塞写线程
}
System.out.println("写入操作: index =  " + putptr + " value = " + x);
items[putptr++] = x;
if (putptr == items.length)
putptr = 0;// 如果写索引写到队列的最后一个位置了，那么置为0
++count;// 个数++
notEmpty.signal();// 唤醒读线程
} finally {
lock.unlock();
}
}
public Object take() throws InterruptedException {
lock.lock();
try {
while (count == 0)
// 如果队列为空
notEmpty.await();// 阻塞读线程
Object x = items[takeptr];// 取值
System.out.println("读取操作: index =" + takeptr + " vale = " + x);
if (++takeptr == items.length)
takeptr = 0;// 如果读索引读到队列的最后一个位置了，那么置为0
--count;// 个数--
notFull.signal();// 唤醒写线程
return x;
} finally {
lock.unlock();
}
}
public static void main(String[] args) {
final BufferThread bt = new BufferThread();
Thread t1 = new Thread(new Runnable() {
@Override
public void run() {
for (int i = 0; i < 250; i++)
try {
bt.put(i);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
Thread t2 = new Thread(new Runnable() {
@Override
public void run() {
for (int i = 0; i < 230; i++)
try {
bt.take();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
t1.start();
t2.start();
}
}

参考：http://blog.csdn.net/ghsau/article/details/7481142