同步模式之顺序控制

同步模式之顺序控制

固定运行顺序

比如,必须先打印1再打印2

wait&notify版

代码实现

@Slf4j(topic = "c.ControllerStepDemo")
public class ControllerStepDemo {
    static final Object lock = new Object();
    static boolean t2Runed = false;
    public static void main(String[] args) {
        Thread t1 = new Thread(()->{
            synchronized (lock){
                while (!t2Runed) {
                    try {
                        lock.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                log.debug("1");
            }
        },"t1");
        Thread t2 = new Thread(()->{
            synchronized (lock){
                log.debug("2");
                t2Runed = true;
                lock.notify();
            }
        },"t2");
        t1.start();
        t2.start();
    }
}

park&unpark

代码实现

public static void main(String[] args) {
    Thread t1 = new Thread(()->{
        LockSupport.park();
        log.debug("1");
    },"t1");
    t1.start();
    new Thread(()->{
        log.debug("2");
        LockSupport.unpark(t1);
    },"t2").start();
}

交替输出

线程1输出a5次,线程2输出b5次,线程3输出c5次。要求输出结果为abcabcabcabcabc

wait&notify

public class ControllerStepDemo2 {

    public static void main(String[] args) {
        WaitNotify waitNotify = new WaitNotify(1, 5);
        new Thread(()->{
            waitNotify.print("a",1,2);
        },"t1").start();
        new Thread(()->{
            waitNotify.print("b",2,3);
        },"t2").start();
        new Thread(()->{
            waitNotify.print("c",3,1);
        },"t3").start();
    }
}

class WaitNotify{
    //打印
    public void print(String str,int waitFlage,int nextFlage){
        for (int i = 0; i < loopNumber; i++) {
            synchronized (this){
                while (flage!=waitFlage){
                    try {
                        this.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                System.out.print(str);
                flage = nextFlage;
                this.notifyAll();
            }
        }
    }

    //等待标记
    private int flage;
    //循环次数
    private int loopNumber;

    public WaitNotify(int flage, int loopNumber) {
        this.flage = flage;
        this.loopNumber = loopNumber;
    }
}

await&sign

public class ControllerStepDemo2 {

    public static void main(String[] args) throws InterruptedException {
        AwaitSignal awaitSignal = new AwaitSignal(5);
        Condition a = awaitSignal.newCondition();
        Condition b = awaitSignal.newCondition();
        Condition c = awaitSignal.newCondition();
        new Thread(()->{
            awaitSignal.print("a",a,b);
        },"t1").start();
        new Thread(()->{
            awaitSignal.print("b",b,c);
        },"t2").start();
        new Thread(()->{
            awaitSignal.print("c",c,a);
        },"t3").start();
        Thread.sleep(1000);
        awaitSignal.lock();
        try {
            a.signal();
        }finally {
            awaitSignal.unlock();
        }
    }
}

class AwaitSignal extends ReentrantLock {

    private int loopNumber;

    public AwaitSignal(int loopNumber){
        this.loopNumber = loopNumber;
    }

    public void print(String str,Condition current,Condition next){
        for (int i = 0; i < loopNumber; i++) {
            lock();
            try {
                current.await();
                System.out.print(str);
                next.signal();
            } catch (InterruptedException e) {
                e.printStackTrace();
            } finally {
                unlock();
            }
        }
    }
}

park&unpark

public class ControllerStepDemo2 {
    static Thread t1;
    static Thread t2;
    static Thread t3;
    public static void main(String[] args) throws InterruptedException {
        ParkUnpark parkUnpark = new ParkUnpark(5);
        t1 = new Thread(()->{
            parkUnpark.print("a",t2);
        });
        t2 = new Thread(()->{
            parkUnpark.print("b",t3);
        });
        t3 = new Thread(()->{
            parkUnpark.print("c",t1);
        });
        t1.start();
        t2.start();
        t3.start();
        Thread.sleep(1000);
        LockSupport.unpark(t1);
    }
}

class ParkUnpark{
    public void print(String str,Thread next){
        for (int i = 0; i < 5; i++) {
            LockSupport.park();
            System.out.print(str);
            LockSupport.unpark(next);
        }
    }

    private int loopNumber;

    public ParkUnpark(int loopNumber){
        this.loopNumber = loopNumber;
    }
}

原文地址：https://blog.csdn.net/m0_75113406/article/details/143518507

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