（1）多线程创建

创建多线程的方式

1. 继承Thread类并重写run()方法

2. 实现Runnable接口

3. 实现Callabe接口

4. 匿名内部类以及lambda表达式

5. 线程池

6. Spring异步方法

7. 定时器（java.util.Timer）

 

下面详细的介绍每种创建方式

1.继承Thread类并重写run()方法

public class CreatingThread01 extends Thread {

    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName()+ " is running");
    }

    public static void main(String[] args) {
        new CreatingThread01().start();
        new CreatingThread01().start();
    }
}

2.实现Runnable接口

public class CreatingThread02 implements Runnable {
    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName() + " is running");
    }

    public static void main(String[] args) {
        new Thread(new CreatingThread02()).start();
        new Thread(new CreatingThread02()).start();
    }
}

3.实现Callabe接口

public class CreatingThread03 implements Callable<Long> {
    @Override
    public Long call() throws Exception {
        TimeUnit.SECONDS.sleep(1);
        System.out.println(Thread.currentThread().getName()+ " is running");
        return Thread.currentThread().getId();
    }

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        FutureTask<Long> task = new FutureTask<>(new CreatingThread03());
        new Thread(task).start();
        System.out.println("等待完成任务");
        Long result = task.get();
        System.out.println("任务结果：" + result);
    }
}

4.匿名内部类

public class CreatingThread04 {
    public static void main(String[] args) {
        // Runnable匿名类，实现其run()方法
        new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println(Thread.currentThread().getName() + " is running");
            }
        }).start();

        // 同上，使用lambda表达式
        new Thread(() -> {
            System.out.println(Thread.currentThread().getName() + " is running");
        }).start();
    }
}

5.线程池

public class CreatingThread05 {
    public static void main(String[] args) {
        ExecutorService threadPool = Executors.newFixedThreadPool(5);
        for (int i = 0; i < 10; i++) {
            threadPool.execute(()-> System.out.println(Thread.currentThread().getName() + " is running"));
        }
    }
}

6.Spring异步方法

 

首先，springboot启动类加上@EnableAsync注解

 

@SpringBootApplication
@EnableAsync
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

然后方法加上@Async注解

@Service
public class CreatingThread06Service {

    @Async
    public void call() {
        System.out.println(Thread.currentThread().getName() + " is running");
    }
}

测试用例

@RunWith(SpringRunner.class)
@SpringBootTest(classes = Application.class)
public class CreatingThread06Test {
    @Autowired
    private CreatingThread06Service creatingThread06Service;

    @Test
    public void test() {
        creatingThread06Service.call();
        creatingThread06Service.call();
    }
}

7.定时器（java.util.Timer）

public class CreatingThread07 {
    public static void main(String[] args) {
        Timer timer = new Timer();
        // 每隔1秒执行一次
        timer.schedule(new TimerTask() {
            @Override
            public void run() {
                System.out.println(Thread.currentThread().getName() + " is running");
            }
        }, 0 , 1000);
    }
}