Java实现多线程

Java实现多线程的方式有4种分别是继承Thread类，实现Runnable，Callable接口和通过线程池提交线程任务。其中实现Callable接口的方式可以获取返回值。

1. 继承Thread类

通过继承Thread类，重写run方法

public class ThreadExtends extends Thread {

    @Override
    public void run() {
        System.out.println("通过继承Thread类实现Java多线程,当前线程："
                +"["+Thread.currentThread().getName()+"]");
    }

    public static void main(String[] args) {
        System.out.println("当前线程："+"["+Thread.currentThread().getName()+"]");
        new ThreadExtends().start();
    }
}

2. 实现Runnable接口

通过实现Runnable接口

public class RunnableImpl implements Runnable {

    @Override
    public void run() {
        System.out.println("通过实现Runnable接口实现Java多线程,当前线程："
                + "[" + Thread.currentThread().getName() + "]");
    }

    public static void main(String[] args) {
        System.out.println("当前线程："+"["+Thread.currentThread().getName()+"]");
        new Thread(new RunnableImpl()).start();
    }
}

3. 实现Callable接口

通过实现Callable接口，使用FutureTask包装器实现Java的多线程。可以通过get方法获取返回值。

public class CallableImpl implements Callable<String> {

    @Override
    public String call() throws Exception {
        System.out.println("通过实现Callable接口实现Java多线程,当前线程："
                + "[" + Thread.currentThread().getName() + "]");
        return "通过实现Callable接口实现Java多线程";
    }

    public static void main(String[] args) {
        Callable<String> task = new CallableImpl();
        FutureTask<String> futureTask = new FutureTask<>(task);
        new Thread(futureTask).start();
        System.out.println("当前线程："+"["+Thread.currentThread().getName()+"]");
        try {
            String result = futureTask.get();
            System.out.println("result = " + result);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    }
}

4. 通过线程池创建多线程

使用线程池，提交任务，实现java多线程。

    public void threadPool() {
        ExecutorService service = Executors.newFixedThreadPool(4);
        //1. RunnableTask
        Runnable runTask = () ->
                System.out.println("当前线程：" + "[" +
                        Thread.currentThread().getName() + "]");
        service.submit(runTask);

        //2.CallableTask: 通过实现Callable接口创建的线程任务
        Callable<String> callTask = () -> {
            System.out.println("当前线程：" + "[" +
                    Thread.currentThread().getName() + "]");
            return Thread.currentThread().getName();
        };
        service.submit(callTask);

        //3. 通过FutureTask 封装器封装Callable实现类提交任务
        FutureTask<String> futureTask = new FutureTask<>(callTask);
        service.submit(futureTask);

        //4. 提交Thread任务
        service.submit(new Thread(runTask));
        service.shutdown();
    }