Java多线程详解多线程龟兔赛跑实力及实现Callable接口

Posted 2021-12-03 轻狂书生han

抢票

 package com.xiancheng.demo01;

//多个线程透视操作同一个对象
//买火车票的例子

//发现问题：多个线程操作同一个资源的情况系啊，线程不安全，数据紊乱
public class TestThread4 implements Runnable{

    //票数
    private int ticketNums = 10;

    @Override
    public void run() {
        while (true){
            if (ticketNums<=0){
                break;
            }
            //模拟延时
            try {
                Thread.sleep(200);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            System.out.println(Thread.currentThread().getName()+"拿到了第"+ticketNums--+"张票");
        }
    }

    public static void main(String[] args) {

        TestThread4 ticket = new TestThread4();

        new Thread(ticket,"小明").start();
        new Thread(ticket,"老师").start();
        new Thread(ticket,"黄牛党").start();


    }

}

案例：龟兔赛跑

1.首先来个赛道距离，然后要离重点越来越近

2.判断比赛是否结束

3.打印出胜利者

4.龟兔赛跑开始

5.故事中是乌龟赢得，兔子需要睡觉，所以我们来模拟兔子睡觉

6.终于乌龟赢得比赛

package com.xiancheng.demo01;

//模拟龟兔赛跑
public class Race implements Runnable{

    //胜利者
    private static String winner;


    @Override
    public void run() {
        for (int i = 0; i <= 100; i++) {

            //模拟兔子休息
            if(Thread.currentThread().getName().equals("兔子")&&i/10==0){
                try {
                    Thread.sleep(10);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }


            //判断比赛是否结束
            boolean flag = gameOver(i);
            //如果比赛结束了，就停止程序
            if (flag){
                break;
            }
            System.out.println(Thread.currentThread().getName()+"跑了"+i+"步");


        }
    }

    //判断是否完成比赛
    private boolean gameOver(int steps){
        //判断是否由胜利者
        if(winner!=null){//已经有胜利者了
            return true;
        }{
            if (steps>=100){
                winner = Thread.currentThread().getName();
                System.out.println("winner is "+winner);
                return true;
            }
        }
        return false;
    }

    public static void main(String[] args) {
        Race race = new Race();


        new Thread(race,"兔子").start();
        new Thread(race,"乌龟").start();
    }

}

实现Callable接口（了解即可）

• 实现Callable接口，需要返回值类型
• 重写call方法，需要抛出异常
• 创建目标对象
• 创建执行服务：ExecutorService ser = Executors.newFixedThreadPool(1);
• 提交执行：Future result1 = ser.submit(t1);
• 获取结果：boolean ri = result.get();
• 关闭服务：ser.shutdownNow();

package com.xiancheng.demo02;

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.concurrent.*;

//线程创建方式三，实现Callable接口
/*
callable的好处
1.可以定义返回值
2.可以抛出异常
 */
public class TestCallable implements Callable<Boolean> {


    private String url;//网络图片地址
    private String name;//保存文件名

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

    }


    @Override
    public Boolean call() {

        WebDownloader webDownloader = new WebDownloader();
        webDownloader.downloader(url,name);
        System.out.println("下载了文件名为："+name);
        return true;
    }

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        TestCallable testThread1 = new TestCallable("https://imgoss.douyucdn.cn/bj/yuba/default/2019/12/20/201912200221045779841615885.jpg","1.jpg");
        TestCallable testThread2 = new TestCallable("https://imgoss.douyucdn.cn/bj/yuba/default/2021/03/26/202103262200428765268485985.jpg","2.jpg");
        TestCallable testThread3 = new TestCallable("https://img.douyucdn.cn/data/yuba/default/2019/08/18/201908182138163129577786480.200x0.jpg","3.jpg");

        //创建执行服务：
        ExecutorService ser = Executors.newFixedThreadPool(3);
        //提交执行
        Future<Boolean> r1 = ser.submit(testThread1);
        Future<Boolean> r2 = ser.submit(testThread2);
        Future<Boolean> r3 = ser.submit(testThread3);
        //获取结果
        boolean rs1 = r1.get();
        boolean rs2 = r2.get();
        boolean rs3 = r3.get();

        System.out.println(rs1);
        System.out.println(rs2);
        System.out.println(rs3);


        //关闭服务
        ser.shutdownNow();

        }

}


//下载器
class WebDownloader {
    //下载方法
    public void downloader(String url, String name) {
        try {
            FileUtils.copyURLToFile(new URL(url), new File(name));
        } catch (IOException e) {
            e.printStackTrace();
            System.out.println("IO异常，downloader方法出现问题");
        }
    }
}

静态代理

package com.xiancheng.demo02;

//静态代理模式总结
//真实对象和代理对象都要实现同一个接口
//代理对象要代理真实角色

//好处
    //代理对象可以做很多真实对象做不了的事
    //真实对象专注做自己的事情

public class StaticProxy {
    public static void main(String[] args) {

        new Thread( ()-> System.out.println("我爱你") ).start();

        new WeddingCompany(new You()).HappyMarry();

        You you = new You();//你要结婚

        //WeddingCompany weddingCompany = new WeddingCompany(new You());
        //weddingCompany.HappyMarry();
    }
}

interface Marry{
    //人间四大喜事
        //久旱逢甘霖
        //他乡遇故知
        //洞房花烛夜
        //金榜题名时

    void HappyMarry();
}

//真实角色，你去结婚
class You implements Marry{
    @Override
    public void HappyMarry(){
        System.out.println("秦老师要结婚了，敲开心");
        }
}

//代理角色，帮你结婚
class WeddingCompany implements Marry{

    //代理谁--》真实目标角色
    private Marry targer;

    public WeddingCompany(Marry targer) {
        this.targer = targer;
    }

    @Override
    public void HappyMarry() {

        before();
        this.targer.HappyMarry();//这就是真实对象
        after();
    }

    private void after() {
        System.out.println("结婚之后，收尾款");

    }

    private void before() {
        System.out.println("结婚之前，布置现场");

    }
}