Java並發：線程間數據傳遞和交換

轉自：https://www.cnblogs.com/java-zzl/p/9741288.html

一、通過SynchronousQueue方式實現線程間數據傳遞：

　　線程A與線程B共同持有一個SynchronousQueue的引用，線程B調用take方法，阻塞以等待； 線程A運行后計算出結果，將結果put到queue中;

public class SynchronousQueueTest {
    public static void main(String[] args) throws InterruptedException {

        SynchronousQueue<Integer> queue = new SynchronousQueue<Integer>();
        //線程A putThread
        Thread putThread = new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("put thread start");
                try {
                    Thread.sleep(3000);
                    System.out.println("put thread put對象");
                    queue.put(1);
                } catch (InterruptedException e) {
                }
                System.out.println("put thread end");
            }
        });
        //線程B takeThread
        Thread takeThread = new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("take thread start");
                try {
                    System.out.println("take thread 等待put對象");
                    System.out.println("take from putThread: " + queue.take());
                } catch (InterruptedException e) {
                }
                System.out.println("take thread end");
            }
        });

        putThread.start();
        takeThread.start();
    }
}

 二、線程Exchanger工具類實現線程間的數據交換：

　　當一個線程到達exchange調用點時，如果它的伙伴線程此前已經調用了此方法，那么它的伙伴會被調度喚醒並與之進行對象交換，然后各自返回。如果它的伙伴還沒到達交換點，那么當前線程將會被掛起，直至伙伴線程到達——完成交換正常返回；或者當前線程被中斷——拋出中斷異常；又或者是等候超時——拋出超時異常。

public class ExchangerTest {

    public static void main(String[] args) {
        ExecutorService service = Executors.newCachedThreadPool();
        final Exchanger exchanger = new Exchanger();
        service.execute(new Runnable(){
            public void run() {
                try {                
                    String data1 = "thread-1-data";
                    System.out.println("線程" + Thread.currentThread().getName() +"正在把數據" + data1 +"換出去");
                    Thread.sleep((long)(Math.random()*10000));
                    String data2 = (String)exchanger.exchange(data1);
                    System.out.println("線程" + Thread.currentThread().getName() + "換回的數據為" + data2);
                }catch(Exception e){
                    
                }
            }    
        });
        service.execute(new Runnable(){
            public void run() {
                try {                
                    String data1 = "thread-2-data";
                    System.out.println("線程" + Thread.currentThread().getName() + "正在把數據" + data1 +"換出去");
                    Thread.sleep((long)(Math.random()*10000));                    
                    String data2 = (String)exchanger.exchange(data1);
                    System.out.println("線程" + Thread.currentThread().getName() + "換回的數據為" + data2);
                }catch(Exception e){
                    
                }                
            }    
        });        
    }
}