Java实现经典八锁问题

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下面将通过经典的8锁问题，认清锁原理

import java.util.concurrent.TimeUnit;


public class LockDemo1 {
    public static void main(String[] args) throws InterruptedException {
        Phone1 phone1 = new Phone1();
        new Thread(()->{
            phone1.sendEmail();
        },"A").start();
        TimeUnit.SECONDS.sleep(3);
        new Thread(()->{
            phone1.callPhone();
        },"B").start();
    }
}
class Phone1{
    public synchronized void sendEmail(){
        System.out.println("senEmail");
    }
    public synchronized  void callPhone(){
        System.out.println("callPhone");
    }
}

import java.util.concurrent.TimeUnit;


public class LockDemo2 {
    public static void main(String[] args) throws InterruptedException {
        Phone2 phone2 = new Phone2();
        new Thread(()->{
            try {
                phone2.sendEmail();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        },"A").start();
        TimeUnit.SECONDS.sleep(2); // 休眠2秒
        new Thread(()->{
            phone2.callPhone();
        },"B").start();
    }
}
class Phone2{
    public synchronized void sendEmail() throws InterruptedException {
        TimeUnit.SECONDS.sleep(3);
        System.out.println("sendEmail");
    }
    public synchronized void callPhone(){
        System.out.println("callPhone");
    }
}

import java.util.concurrent.TimeUnit;


public class LockDemo3 {
    public static void main(String[] args) throws InterruptedException {
        Phone3 phone3 = new Phone3();
        new Thread(()->{
            try {
                phone3.sendEmail();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        },"A").start();

        TimeUnit.SECONDS.sleep(2);
        new Thread(()->{
            phone3.callPhone();
        },"B").start();
    }
}
class Phone3{
    public synchronized void sendEmail() throws InterruptedException {
        TimeUnit.SECONDS.sleep(4);
        System.out.println("sendEmail");
    }

    // 没有synchronized 没有static 就是普通方式
    public void callPhone(){
        System.out.println("callPhone");
    }
}

import java.util.concurrent.TimeUnit;


public class LockDemo4 {
    public static void main(String[] args) throws InterruptedException {
        Phone4 phoneA = new Phone4();
        Phone4 phoneB = new Phone4();

        new Thread(()->{
            try {
                phoneA.sendEmail();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        },"A").start();

        TimeUnit.SECONDS.sleep(1);
        new Thread(()->{
            phoneB.callPhone();
        },"B").start();
    }
}
class Phone4{
    public synchronized void sendEmail() throws InterruptedException {
        TimeUnit.SECONDS.sleep(3);
        System.out.println("sendEmail");
    }
    public synchronized void callPhone(){
        System.out.println("callPhone");
    }
}

import java.util.concurrent.TimeUnit;


public class LockDemo5 {
    public static void main(String[] args) throws InterruptedException {
        Phone5 phone5 = new Phone5();
        new Thread(()->{
            try {
                phone5.sendEmail();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        },"A").start();

        TimeUnit.SECONDS.sleep(1);
        new Thread(()->{
            phone5.callPhone();
        },"B").start();
    }
}
class Phone5{
    public static synchronized void sendEmail() throws InterruptedException {
        TimeUnit.SECONDS.sleep(3);
        System.out.println("sendEmail");
    }

    public static synchronized void callPhone(){
        System.out.println("callPhone");
    }
}

import java.util.concurrent.TimeUnit;


public class LockDemo6 {
    public static void main(String[] args) throws InterruptedException {
        Phone6 phone6 = new Phone6();
        new Thread(()->{
            try {
                phone6.sendEmail();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        },"A").start();

        TimeUnit.SECONDS.sleep(1);
        new Thread(()->{
            phone6.callPhone();
        },"B").start();
    }
}
class Phone6{
    public static synchronized void sendEmail() throws InterruptedException {
        TimeUnit.SECONDS.sleep(3);
        System.out.println("sendEmail");
    }

    public synchronized void callPhone(){
        System.out.println("callPhone");
    }
}

import java.util.concurrent.TimeUnit;


public class LockDemo7 {
    public static void main(String[] args) throws InterruptedException {
        Phone7 phoneA = new Phone7();
        Phone7 phoneB = new Phone7();

        new Thread(()->{
            try {
                phoneA.sendEmail();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        },"A").start();

        TimeUnit.SECONDS.sleep(1);
        new Thread(()->{
            phoneB.callPhone();
        },"B").start();
    }
}
class Phone7{
    public static synchronized void sendEmail() throws InterruptedException {
        TimeUnit.SECONDS.sleep(3);
        System.out.println("sendEmail");
    }

    public static synchronized void callPhone(){
        System.out.println("callPhone");
    }
}

import java.util.concurrent.TimeUnit;


public class LockDemo8 {
    public static void main(String[] args) throws InterruptedException {
        Phone8 phoneA = new Phone8();
        Phone8 phoneB = new Phone8();

        new Thread(()->{
            try {
                phoneA.sendEmail();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        },"A").start();

        TimeUnit.SECONDS.sleep(1);
        new Thread(()->{
            phoneB.callPhone();
        },"B").start();
    }
}
class Phone8{
    public static synchronized void sendEmail() throws InterruptedException {
        TimeUnit.SECONDS.sleep(3);
        System.out.println("sendEmail");
    }

    public synchronized void callPhone(){
        System.out.println("callPhone");
    }
}

小结：

synchronized(Demo.class){

}
synchronized(this){

}

1、new this 调用的是这个对象，是一个具体的对象！
2、static class 唯一的一个模板！

在我们编写多线程程序得时候，只需要搞明白这个到底锁的是什么就不会出错了！