Java 创建线程的四种方式

你的名字 2020-06-14 10:09 960阅读 0赞

## 继承Thread类 ##

步骤

1.  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
2.  创建自定义的线程子类对象
3.  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

1.  定义Runnable接口实现类MyRunnable，并重写run()方法
2.  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**
3.  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

1.  创建实现Callable接口的类myCallable
2.  以myCallable为参数创建FutureTask对象
3.  将FutureTask作为参数创建Thread对象
4.  调用线程对象的start()方法

public class MyCallable implements Callable<Integer> {
    
        @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 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...