线程生命周期，创建方式以及如何实现同步和通信

线程的生命周期

利用继承的方式创建线程并实现同步

package com.vegeta;

/**
 * 继承方式创建线程，实现同步
 *
 * @author：qxz
 * @create 2020-04-02 10:45
 */
public class TestExtends {

    public static void main(String[] args) {
        Window window1 = new Window();
        window1.setName("窗口一");
        Window window2 = new Window();
        window2.setName("窗口二");
        Window window3 = new Window();
        window3.setName("窗口三");
        window1.start();
        window2.start();
        window3.start();
    }

}

class Window extends Thread {
    private static int ticket = 100;

    @Override
    public void run() {
        while (true) {
            synchronized (Window.class) {
                if (ticket > 0) {
                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println(Thread.currentThread().getName() + "卖出了第" + ticket + "号票");
                    ticket--;
                } else {
                    break;
                }
            }
        }
    }
}

利用实现Runnable接口创建多线程并实现同步

package com.vegeta;

/**
 * 利用实现Runnable接口方式创建多线程并实现同步
 *
 * @author：qxz
 * @create 2020-04-02 11:14
 */
public class TestRunnable {
    public static void main(String[] args) {
        WindowRunnable windowRunnable = new WindowRunnable();
        Thread window1 = new Thread(windowRunnable);
        window1.setName("窗口一");
        Thread window2 = new Thread(windowRunnable);
        window2.setName("窗口二");
        Thread window3 = new Thread(windowRunnable);
        window3.setName("窗口三");
        window1.start();
        window2.start();
        window3.start();
    }
}

class WindowRunnable implements Runnable{
    private int ticket = 100;

    public void run() {
        while (true) {
            synchronized (this) {
                if (ticket > 0) {
                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println(Thread.currentThread().getName() + "卖出了第" + ticket + "号票");
                    ticket--;
                } else {
                    break;
                }
            }
        }
    }
}

实现Callable接口创建多线程，Callable接口不适合这种场景，它是带返回值的

package com.vegeta;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;

/**
 * 实现Callable接口能获取返回值
 *
 * @author：qxz
 * @create 2020-04-02 11:32
 */
public class TestCallable {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        WindowCallable wc = new WindowCallable();
        FutureTask<Integer> futureTask1 = new FutureTask(wc);
        FutureTask<Integer> futureTask2 = new FutureTask(wc);
        FutureTask<Integer> futureTask3 = new FutureTask(wc);
        Thread window1 = new Thread(futureTask1);
        window1.setName("窗口一");
        Thread window2 = new Thread(futureTask2);
        window2.setName("窗口二");
        Thread window3 = new Thread(futureTask3);
        window3.setName("窗口三");
        window1.start();
        Integer i1 = futureTask1.get();
        System.out.println(i1);
        window2.start();
        Integer i2 = futureTask2.get();
        System.out.println(i2);
        window3.start();
        Integer i3 = futureTask3.get();
        System.out.println(i3);

        System.out.println(i1 + i2 + i3);
    }
}

class WindowCallable implements Callable<Integer>{

    public Integer call() throws Exception {
       return 1 + 2;
    }
}

利用线程池实现同步

package com.vegeta;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;

/**
 * 利用线程池 实现同步
 * 
 * @author：qxz
 * @create 2020-04-02 13:29
 */
public class TestPool {
    public static void main(String[] args) {
        ExecutorService executorService = Executors.newFixedThreadPool(10);
        ThreadPoolExecutor executor = (ThreadPoolExecutor) executorService;
        WindowPool windowPool = new WindowPool();
        executor.execute(windowPool);
        executor.execute(windowPool);
        executor.execute(windowPool);
        executor.shutdown();
    }
}

class WindowPool implements Runnable{
    private int ticket = 100;

    public void run() {
        while (true) {
            synchronized (this) {
                if (ticket > 0) {
                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println(Thread.currentThread().getName() + "卖出了第" + ticket + "号票");
                    ticket--;
                } else {
                    break;
                }
            }
        }
    }
}

线程交互

/**
 * 线程通信的例子：使用两个线程打印 1-100。线程1, 线程2 交替打印
 *
 * 涉及到的三个方法：
 * wait():一旦执行此方法，当前线程就进入阻塞状态，并释放同步监视器。
 * notify():一旦执行此方法，就会唤醒被wait的一个线程。如果有多个线程被wait，就唤醒优先级高的那个。
 * notifyAll():一旦执行此方法，就会唤醒所有被wait的线程。
 *
 * 说明：
 * 1.wait()，notify()，notifyAll()三个方法必须使用在同步代码块或同步方法中。
 * 2.wait()，notify()，notifyAll()三个方法的调用者必须是同步代码块或同步方法中的同步监视器。
 *    否则，会出现IllegalMonitorStateException异常
 * 3.wait()，notify()，notifyAll()三个方法是定义在java.lang.Object类中。
 *
 * 面试题：sleep() 和 wait()的异同？
 * 1.相同点：一旦执行方法，都可以使得当前的线程进入阻塞状态。
 * 2.不同点：1）两个方法声明的位置不同：Thread类中声明sleep() , Object类中声明wait()
 *          2）调用的要求不同：sleep()可以在任何需要的场景下调用。 wait()必须使用在同步代码块或同步方法中
 *          3）关于是否释放同步监视器：如果两个方法都使用在同步代码块或同步方法中，sleep()不会释放锁，wait()会释放锁。
 *
 * @author shkstart
 * @create 2019-02-15 下午 4:21
 */
public class CommunicationTest {
    public static void main(String[] args) {
        Number number = new Number();
        Thread t1 = new Thread(number);
        Thread t2 = new Thread(number);

        t1.setName("线程1");
        t2.setName("线程2");

        t1.start();
        t2.start();
    }
}

class Number implements Runnable{
    private int number = 1;

    public void run() {
        while(true){
            synchronized (this) {
                this.notify();
                if(number <= 100){
                    try {
                        Thread.sleep(10);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println(Thread.currentThread().getName() + ":" + number);
                    number++;
                    try {
                        //使得调用如下wait()方法的线程进入阻塞状态
                        this.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }else{
                    break;
                }
            }
        }
    }
}