java concurrent 之 semaphore
java.util.concurrent.Exchanger类表示一种会聚点，其中两个线程可以交换对象。 这是一个这个机制的例证
image
通过两种exchange（）方法之一来完成交换对象。 这是一个例子：
Exchanger exchanger = new Exchanger();
ExchangerRunnable exchangerRunnable1 =
new ExchangerRunnable(exchanger, "A");
ExchangerRunnable exchangerRunnable2 =
new ExchangerRunnable(exchanger, "B");
new Thread(exchangerRunnable1).start();
new Thread(exchangerRunnable2).start();
public class ExchangerRunnable implements Runnable{
Exchanger exchanger = null;
Object object = null;
public ExchangerRunnable(Exchanger exchanger, Object object) {
this.exchanger = exchanger;
this.object = object;
}
public void run() {
try {
Object previous = this.object;
this.object = this.exchanger.exchange(this.object);
System.out.println(
Thread.currentThread().getName() +
" exchanged " + previous + " for " + this.object
);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
输出
Thread-0 exchanged A for B
Thread-1 exchanged B for A
