Java 创建线程的四种方式-蒲公英云

Java 创建线程的四种方式

你的名字 2020-06-14 10:09 1085阅读 0赞

继承Thread类

步骤

定义一个Thread类的子类，重写run方法，将相关逻辑实现，run()方法就是线程要执行的业务逻辑方法
创建自定义的线程子类对象

调用子类实例的star()方法来启动线程

public class MyThread extends Thread {

@Override
public void run() {
    System.out.println(Thread.currentThread().getName() + " run()方法正在执行...");
}

}

public class TheadTest {

public static void main(String[] args) {
    MyThread myThread = new MyThread();     
    myThread.start();
    System.out.println(Thread.currentThread().getName() + " main()方法执行结束");
}

}

运行结果

main main()方法执行结束
Thread-0 run()方法正在执行...

实现Runnable接口

步骤

定义Runnable接口实现类MyRunnable，并重写run()方法
创建MyRunnable实例myRunnable，以myRunnable作为target创建Thead对象，该Thread对象才是真正的线程对象

调用线程对象的start()方法

public class MyRunnable implements Runnable {

@Override
public void run() {
    System.out.println(Thread.currentThread().getName() + " run()方法执行中...");
}

}

public class RunnableTest {

public static void main(String[] args) {
    MyRunnable myRunnable = new MyRunnable();
    Thread thread = new Thread(myRunnable);
    thread.start();
    System.out.println(Thread.currentThread().getName() + " main()方法执行完成");
}

}

执行结果

main main()方法执行完成
Thread-0 run()方法执行中...

使用Callable和Future创建线程

步骤

创建实现Callable接口的类myCallable
以myCallable为参数创建FutureTask对象
将FutureTask作为参数创建Thread对象

调用线程对象的start()方法

public class MyCallable implements Callable {

@Override
public Integer call() {
    System.out.println(Thread.currentThread().getName() + " call()方法执行中...");
    return 1;
}

}

public class CallableTest {

public static void main(String[] args) {
    FutureTask<Integer> futureTask = new FutureTask<Integer>(new MyCallable());
    Thread thread = new Thread(futureTask);
    thread.start();
    try {
        Thread.sleep(1000);
        System.out.println("返回结果 " + futureTask.get());
    } catch (InterruptedException e) {
        e.printStackTrace();
    } catch (ExecutionException e) {
        e.printStackTrace();
    }
    System.out.println(Thread.currentThread().getName() + " main()方法执行完成");
}

}

执行结果

Thread-0 call()方法执行中...
返回结果 1
main main()方法执行完成

使用Executor框架创建线程池

Executors提供了一系列工厂方法用于创先线程池，返回的线程池都实现了ExecutorService接口。

主要有newFixedThreadPool，newCachedThreadPool，newSingleThreadExecutor，newScheduledThreadPool，后续详细介绍这四种线程池

public class MyRunnable implements Runnable {
    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName() + " run()方法执行中...");
    }
}
public class SingleThreadExecutorTest {
    public static void main(String[] args) {
        ExecutorService executorService = Executors.newSingleThreadExecutor();
        MyRunnable runnableTest = new MyRunnable();
        for (int i = 0; i < 5; i++) {
            executorService.execute(runnableTest);
        }
        System.out.println("线程任务开始执行");
        executorService.shutdown();
    }
}

执行结果

线程任务开始执行
pool-1-thread-1 is running...
pool-1-thread-1 is running...
pool-1-thread-1 is running...
pool-1-thread-1 is running...
pool-1-thread-1 is running...