多线程之案列（电影票）

1.使用的是synchronized 同步代码块

SellTicketDemo2

package com.dml.demo2;

public class SellTicketDemo2 {
    public static void main(String[] args) {
        SellTicket mt1 = new SellTicket();

        Thread th1 = new Thread(mt1,"窗口1");
        Thread th2 = new Thread(mt1,"窗口2");
        Thread th3 = new Thread(mt1,"窗口3");

        th1.start();
        th2.start();
        th3.start();
    }
}

SellTicket

package com.dml.demo2;

public class SellTicket implements Runnable{

    private int tickets = 100;
    private Object obj = new Object();
    @Override
    public void run() {
        while(true){
            synchronized (obj) {
                if(tickets > 0){
                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println( Thread.currentThread().getName()+"正在出售第" + (tickets--) + "张票");
                }
            }
        }
    }

}

2.使用synchronized同步方法

package com.dml.demo2;

public class SellTicket implements Runnable{

    private int tickets = 100;
    private Object obj = new Object();
    private int x = 0;
    @Override
    public void run() {
        while(true){
            if(x % 2 == 0){
                //同步方法的锁对象是this
                synchronized (this) {
                    if(tickets > 0){
                        try {
                            Thread.sleep(100);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                        System.out.println( Thread.currentThread().getName()+"正在出售第" + (tickets--) + "张票");
                    }
                }
            }else {
                sell();
            }
            x++;

        }
    }


    public synchronized void sell(){
        if(tickets > 0){
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println( Thread.currentThread().getName()+"正在出售第" + (tickets--) + "张票");
        }
    }
}

注意：同步方法的锁对象是this

3.使用静态的同步方法

package com.dml.demo2;

public class SellTicket implements Runnable{

    private static int tickets = 100;
    private Object obj = new Object();
    private int x = 0;
    @Override
    public void run() {
        while(true){
            if(x % 2 == 0){
                //静态同步方法的锁对象是类的字节码文件
                synchronized (SellTicket.class) {
                    if(tickets > 0){
                        try {
                            Thread.sleep(100);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                        System.out.println( Thread.currentThread().getName()+"正在出售第" + (tickets--) + "张票");
                    }
                }
            }else {
                sell();
            }
            x++;

        }
    }


    public static synchronized void sell(){
        if(tickets > 0){
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println( Thread.currentThread().getName()+"正在出售第" + (tickets--) + "张票");
        }
    }
}

注意：静态同步方法的锁对象是类的字节码文件，因为静态方法随类的加载而加载。

4.使用Lock锁方法

package com.dml.demo3;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

import sun.awt.windows.ThemeReader;

public class SellTicket implements Runnable{

    private int tickets = 100;
    private Lock lock = new ReentrantLock();
    @Override
    public void run() {
        while(true){
            try {
                //获取锁
                lock.lock();

                if(tickets > 0){
                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println(Thread.currentThread().getName() + "正在出售第" + tickets -- + "张票");
                } 
            }finally{
                //释放锁
                lock.unlock();
            }

        }
    }

}

注意：Lock需要自己释放锁