Java併發核心-exchanger

Exchanger類的做用

Exchanger的功能能夠使兩個線程(重點: 只有兩個線程)之間傳輸數據

• 重點是exchange()方法

• exchange()方法是阻塞執行的,能夠設置超時時間 可調用不一樣的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 + "]交換到消息：" + 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();
  		}
  
  	}

• 運行結果
  

• 例: 三個線程操做

  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();
  		}
  
  	}

• 此時程序的運行結果是不肯定的，屢次運行能夠發現，配對結果多是Thread[2]和Thread[3]交換，也多是Thread[1]和Thread[2]交換，而剩下的未獲得配對的線程，則會被阻塞，永久等待，直到與之配對的線程到達位置，對於本程序，則只能強制將其中止

• 阻塞狀態
  

• 可設置五秒超時時間

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

• 運行結果