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LockSupport

原理

贴一个之前的笔记，字迹比拟潦草zz 有空的时候这里会补上阐明

实现1

import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.LockSupport;class Main{    static Thread a = null, b=null;    public static void main(String[] args){        a = new Thread(new Runnable() {            @Override            public void run() {                for(int i = 1;i<=99;i+=2){                    System.out.println(i);                    LockSupport.unpark(b);                    LockSupport.park();                }            }        });        b = new Thread(new Runnable() {            @Override            public void run() {                for(int i = 2;i<=100;i+=2){                    LockSupport.park();                    System.out.println(i);                    LockSupport.unpark(a);                }            }        });        a.start();        b.start();    }}

实现2

import java.util.concurrent.atomic.AtomicInteger;import java.util.concurrent.locks.LockSupport;public class Main {    static AtomicInteger num = new AtomicInteger(1);    public static void main(String[] args) throws InterruptedException {        Print p1 = new Print();        Print p2 = new Print();        Thread t1 = new Thread(p1); //t1对应p1工作 但p1工作的线程挂在t2上不便t1唤醒它        Thread t2 = new Thread(p2);        t1.setName("thread-cc-1");        t2.setName("thread-cc-2");        p1.setT(t2);//给p1的Thread设置为t2不便t1唤醒它        p2.setT(t1);        t1.start();        t2.start();        // 唤醒线程t1打印奇数，线程1打印奇数，线程2打印偶数        LockSupport.unpark(t1);    }    static class Print implements Runnable {        private volatile Thread t;        @Override        public void run() {            while (true) {                // 进入之后立刻阻塞                LockSupport.park();                if (num.get() > 100) {                    LockSupport.unpark(t);                    return;                }                System.out.println(Thread.currentThread().getName() + " : " + num.getAndIncrement());        // 这里的t实际上是与currentThread不同的另一个线程        // 因而实现了 奇数唤醒偶数线程，偶数唤醒奇数线程                LockSupport.unpark(t);            }        }        public void setT(Thread t) {            this.t = t;        }    }}

点评：可拓展性实现2绝对较差一些(实现3个线程交替打印etc)

Synchronized + wait/notify实现

public class Main{    public static void main(String[] args){        MyPrint print = new MyPrint();        Thread thread1 = new Thread(print,"A");        Thread thread2 = new Thread(print,"B");        thread1.start();        thread2.start();    }}class MyPrint implements Runnable{    int i = 1;    @Override    public void run() {        while (true){            synchronized (this){                this.notify();//在这里唤醒的目标是为保障拿到锁的线程只有一个                // 不会立刻开释锁 退出代码块才会开释锁                if (i <= 100){                    System.out.println(Thread.currentThread().getName()+" "+i++);                }else {                    return;                }                try {                    this.wait();//打印过数据的线程期待 必须等到没打印过数字的拿到锁了能力唤醒                } catch (InterruptedException e) {                    e.printStackTrace();                }            }        }    }}