Exchanger类的作用

Exchanger的功能可以使两个线程(重点: 只有两个线程)之间传输数据

• 重点是exchange()方法

• exchange()方法是阻塞执行的,可以设置超时时间 可调用不同的Api

  package com.f.fmodules.fuser.example.exchanger;	import java.util.concurrent.Exchanger;	public class ExchangerThread extends Thread{		private Exchanger
        
          exchanger;		private String threadName;		private String changeString;		ExchangerThread(String threadName, String changeString, Exchanger
         
           exchanger) {			super();			this.threadName = threadName;			this.changeString = changeString;			this.exchanger = exchanger;		}		@Override		public void run() {			try {				System.out.println("Thread[" + threadName + "]交换到消息：" + exchanger.exchange(changeString));			} catch (Exception e) {				e.printStackTrace();			}		}	}
         
        

  package com.f.fmodules.fuser.example.exchanger;	import java.util.concurrent.Exchanger;	public class ExchangerTest {		public static void main(String[] args) {			Exchanger
        
          exchanger = new Exchanger<>();			ExchangerThread t1 = new ExchangerThread("1","changString1", exchanger);			ExchangerThread t2 = new ExchangerThread("2","changString2", exchanger);			t1.start();			t2.start();		}	}
        

• 运行结果

  

• 例: 三个线程操作

  package com.f.fmodules.fuser.example.exchanger;	import java.util.concurrent.Exchanger;	public class ExchangerTest {		public static void main(String[] args) {			Exchanger
        
          exchanger = new Exchanger<>();			ExchangerThread t1 = new ExchangerThread("1","changString1", exchanger);			ExchangerThread t2 = new ExchangerThread("2","changString2", exchanger);			ExchangerThread t3 = new ExchangerThread("3","changString3", exchanger);			t1.start();			t2.start();			t3.start();		}	}
        

• 此时程序的运行结果是不确定的，多次运行可以发现，配对结果可能是Thread[2]和Thread[3]交换，也可能是Thread[1]和Thread[2]交换，而剩下的未得到配对的线程，则会被阻塞，永久等待，直到与之配对的线程到达位置，对于本程序，则只能强制将其停止

• 阻塞状态

  

• 可设置五秒超时时间

  System.out.println("Thread[" + threadName + "]交换到消息：" + exchanger.exchange(changeString, 5, TimeUnit.SECONDS));

• 运行结果