Java并发核心-exchanger

Exchanger类的做用

Exchanger的功能能够使两个线程(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,能够设置超时时间 可调用不一样的Api

  package com.f.fmodules.fuser.example.exchanger;
  
  	import java.util.concurrent.Exchanger;
  
  	public class ExchangerThread extends Thread{
  
  		private Exchanger<String> exchanger;
  		private String threadName;
  		private String changeString;
  
  
  		ExchangerThread(String threadName, String changeString, Exchanger<String> 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<String> 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: 三个线程操做

  package com.f.fmodules.fuser.example.exchanger;
  
  	import java.util.concurrent.Exchanger;
  
  	public class ExchangerTest {
  
  		public static void main(String[] args) {
  			Exchanger<String> 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肯定的，屡次运行能够发现，配对结果多是Thread[2]和Thread[3]交换，也多是Thread[1]和Thread[2]交换，而剩下的未获得配对的线程，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，则只能强制将其中止

• 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