java线程学习1

java实现多线程有三种方式：继承Thread类，重写run方法，启动使用start；实现runnable接口，重写run方法；实现callable接口，重写call方法（可以有返回值，也可以抛出异常）

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1.多线程实现文件下载   利用FileUtils.copyURLtoFile（）

package threadStudy;

import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;

import org.apache.commons.io.FileUtils;

public class WebDownload {

    public void download(String url,String dest) {
        try {
            FileUtils.copyURLToFile(new URL(url), new File(dest));
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            System.out.println("url is error!");
        }
    }
}

package threadStudy;

public class ThreadDownload extends Thread{
    
    String url;
    String dest;

    public ThreadDownload(String url,String dest) {
        this.url = url;
        this.dest = dest;
    }
    
    @Override
    public void run() {
        new WebDownload().download(url, dest);
        System.out.println(dest);
    }
    
    public static void main(String[] args) {
        ThreadDownload t1 = new ThreadDownload("http://pic-bucket.ws.126.net/photo/0001/2019-06-06/EH0TSVI400AP0001NOS.jpg", "linzhiling.jpg");
        ThreadDownload t2 = new ThreadDownload("http://pic-bucket.ws.126.net/photo/0001/2019-06-06/EH0TSVI500AP0001NOS.jpg", "linzhiling2.jpg");
        ThreadDownload t3 = new ThreadDownload("http://pic-bucket.ws.126.net/photo/0001/2019-06-05/EGTO1O6800AN0001NOS.jpg", "rocket.jpg");
        ThreadDownload t4 = new ThreadDownload("http://pic-bucket.ws.126.net/photo/0001/2019-06-05/EGTLGCTO00AN0001NOS.jpg", "rocket2.jpg");
        
        t1.start();
        t2.start();
        t3.start();
        t4.start();
    
    }

}

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模拟抢票（同步问题以后解决）

package threadStudy;

public class Tickets implements Runnable {

    /**
     * 使用runnable 实现线程 有利于共享资源
     */

    private int ticketNumber = 100;

    @Override
    public void run() {
        while (true) {
            if (ticketNumber <= 0) {
                break;
            } else {
                try {
                    Thread.sleep(100);  //模拟线程同步问题
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                System.out.println(Thread.currentThread().getName() + "----->" + ticketNumber--);
            }
        }
    }

    public static void main(String[] args) {
        Tickets t = new Tickets();
        System.out.println(Thread.currentThread().getName());
        new Thread(t,"黄牛一").start();
        new Thread(t,"黄牛二").start();
        new Thread(t,"黄牛三").start();
    }
}