实现线程安全的三种方式

一、Synchronized

1. 同步方法

public class MyThread extends Thread{
          
   
    private int ticket = 10000;

	//重写run()方法
    public void run(){
          
   
        while (ticket > 0){
          
   
            this.getTicket();
        }

    }
	//非静态的同步方法同步监视器为this（类的对象）
	//静态的同步方法同步监视器为类本身（MyThread.Class）
    public synchronized void  getTicket(){
          
   
            if (ticket > 0) {
          
   
                System.out.println(Thread.currentThread().getName() + "--got ticket with no." + ticket);
                ticket--;
            }
    }

    public static void main(String[] args) {
          
   
        MyThread myThread = new MyThread();
        Thread thread1 = new Thread(myThread);
        Thread thread2 = new Thread(myThread);
        Thread thread3 = new Thread(myThread);
        thread1.setName("用户1");
        thread2.setName("用户2");
        thread3.setName("用户3");
        //调用start()方法开启多线程执行
        thread1.start();
        thread2.start();
        thread3.start();
    }

1. 同步代码块

public class MyThread2 extends Thread {
          
   
    private int ticket = 10000;
    //重写run()方法
    public void run(){
          
   
        while (ticket > 0) {
          
   
            synchronized (this) {
          
   
                if (ticket > 0) {
          
   
                    System.out.println(Thread.currentThread().getName() + "--got ticket with no." + ticket);
                    ticket--;
                } else {
          
   
                    break;
                }
            }
        }

    }
    public static void main(String[] args) {
          
   
        MyThread2 myThread2 = new MyThread2();
        Thread thread1 = new Thread(myThread2);
        Thread thread2 = new Thread(myThread2);
        Thread thread3 = new Thread(myThread2);
        thread1.setName("用户1");
        thread2.setName("用户2");
        thread3.setName("用户3");
        //调用start()方法开启多线程执行
        thread1.start();
        thread2.start();
        thread3.start();
    }
}

二、手动Lock

public class MyThread3 implements Runnable {
          
   
    private int ticket = 100;
    //启用公平锁
    private ReentrantLock lock = new ReentrantLock(true);

    @Override
    public void run() {
          
   
        while (ticket > 0) {
          
   
            try {
          
   
            	//手动上锁
                lock.lock();
                if (ticket > 0) {
          
   
                    try {
          
   
                        Thread.sleep(10);
                    } catch (InterruptedException e) {
          
   
                        e.printStackTrace();
                    }
                    System.out.println(Thread.currentThread().getName() + "--got ticket with no." + ticket);
                    ticket--;
                } else {
          
   
                    break;
                }
            } finally {
          
   
            	//手动释放锁
                lock.unlock();
            }
        }
    }

    public static void main(String[] args) {
          
   
        MyThread3 myThread3 = new MyThread3();
        Thread thread1 = new Thread(myThread3);
        Thread thread2 = new Thread(myThread3);
        Thread thread3 = new Thread(myThread3);
        thread1.start();
        thread2.start();
        thread3.start();
    }
}