Java多线程

继承Thread类

1.继承Thread类

2.重写run()方法

3.调用star方法

public class TestThread1 extends Thread{


    
    @Override
    public void run() {
        for(int i=0;i<200;i++){
            System.out.println("bbbbbbbb");
        }
    }

    public static void main(String[] args) {
        TestThread1 thread=new TestThread1();
        thread.start();

        for (int i=0;i<200;i++){
            System.out.println("aaaaaaaaaaa");
        }
    }
}

实现Runnable接口

1.实现Runnable接口，重写run方法

2.创建当前类的对象

3.创建Thread类对象，使用Runnable接口构造方法

4.调用start方法

public class TestThread3  implements Runnable{
    @Override

    
    public void run() {
        for(int i=0;i<200;i++){
            System.out.println("bbbbbbbb");
        }
    }

    public static void main(String[] args) {
        TestThread3 thread3 = new TestThread3();
        new Thread(thread3).start();

        for (int i=0;i<200;i++){
            System.out.println("aaaaaaaaaaa");
        }
    }
}

好处：可以多个线程公用一个对象

实列：模拟抢票软件

public class TestThread4 implements Runnable{

    private int ticketname=10;
    @Override
    public void run() {
        while(true){
            if(ticketname<=0) break;
            try {
                Thread.sleep(200);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName()+"抢到了第"+ticketname--+"张票");
        }
    }

    public static void main(String[] args) {
        TestThread4 thread4 = new TestThread4();

        new Thread(thread4,"张三").start();
        new Thread(thread4,"李四").start();
        new Thread(thread4,"王五").start();
    }
}

实现Callable接口

1.重写call方法

2.打开服务和线程池

3.将Callable接口扔进线程池

4.关闭服务

实列：多线程同时下载网络图片

public class TestCallable implements Callable {

    private String name;
    private String url;

    public TestCallable(String url, String name) {
        this.name = name;
        this.url = url;
    }

    @Override
    public Boolean call() throws Exception {
        Webloader load =new Webloader();
        load.WebDownloader(name,url);
        System.out.println(Thread.currentThread().getName()+"下载完成了");
        return true;
    }

    public static void main(String[] args) {
        TestCallable t1= new TestCallable("https://img0.baidu.com/it/u=53211142,3579082837&fm=26&fmt=auto","白熊.jpg");
        TestCallable t2= new TestCallable("https://img2.baidu.com/it/u=1868254201,2187725343&fm=26&fmt=auto","棕熊.jpg");
        TestCallable t3= new TestCallable("https://img1.baidu.com/it/u=1615031516,635347996&fm=26&fmt=auto","胖达.jpg");

        ExecutorService ser = Executors.newFixedThreadPool(3);

        Future r1 = ser.submit(t1);
        Future r2 = ser.submit(t2);
        Future r3 = ser.submit(t3);

        ser.shutdown();
    }
}

class Webloader{
    public void WebDownloader(String name,String url){
        try {
            FileUtils.copyURLToFile(new URL(url),new File(name));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

好处：有返回值