java线程实现的三种方式以及静态代理

线程

一个进程中若开辟多个线程，线程的运行由调度器控制，先后顺序不能人为干预。

实现方式

继承 Thread类

调用run方法，只有主线程一条路
调用start方法，主线程和子线程并行交替执行
start方法是进入就绪态

public class MyThread extends Thread{

    @Override
    public void run() {
        for (int i = 0; i < 20; i++) {
            System.out.println("xixi");
        }
    }

    public static void main(String[] args) {

        MyThread myThread = new MyThread();
        //myThread.run();只有主线程一条路，先xixi后haha
        //开启线程，不一定立刻执行，由cpu调度
        myThread.start();//同时运行，xixi、haha交替

        //main线程
        for (int i = 0; i < 20; i++) {
            System.out.println("haha");
        }
    }

}

导入common-io.jar下载图片

import org.apache.commons.io.FileUtils;

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

public class MyThread2 extends Thread{

    private String url;
    private String name;

    public MyThread2(String url, String name){
        this.name = name;
        this.url = url;
    }

    @Override
    public void run() {
        WebDownloader webDownloader = new WebDownloader();
        webDownloader.downloader(url, name);
        System.out.println("下载了文件名为" + name);

    }

    public static void main(String[] args) {
        MyThread2 t1 = new MyThread2("https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=3246675119,2528014287&fm=26&gp=0.jpg", "csgo1.jpg");
        MyThread2 t2 = new MyThread2("https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=3246675119,2528014287&fm=26&gp=0.jpg", "csgo2.jpg");
        MyThread2 t3 = new MyThread2("https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=3246675119,2528014287&fm=26&gp=0.jpg", "csgo3.jpg");

        t1.start();
        t2.start();
        t3.start();

    }
}

class WebDownloader{
    public void downloader(String url, String name){
        try {
            FileUtils.copyURLToFile(new URL(url), new File(name));
        } catch (IOException e) {
            e.printStackTrace();
            System.out.println("downloader异常");
        } finally {
        }
    }
}

实现Runnable接口

推荐使用，避免单继承局限性，灵活方便，方便同一个对象被多个线程使用

public class MyThread3 implements Runnable{
    @Override
    public void run() {
        for (int i = 0; i < 20; i++) {
            System.out.println("xixi");
        }
    }

    public static void main(String[] args) {

        //创建实现runnable接口的类对象
        MyThread3 myThread3 = new MyThread3();
        //创建线程对象，通过线程对象启动线程，代理
        new Thread(myThread3).start();


        for (int i = 0; i < 20; i++) {
            System.out.println("haha");
        }
    }
}

多线程同时操作一个对象

public class MyThread4 implements Runnable{

    private int ticketNums = 10;

    @Override
    public void run() {
        while (true){
            if(ticketNums <= 0)
                break;

            //模拟延时
            try {
                Thread.sleep(20);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName() + "拿到了第" + ticketNums-- + "张票");
        }
    }

    public static void main(String[] args) {
        MyThread4 myThread4 = new MyThread4();
        new Thread(myThread4, "haha").start();
        new Thread(myThread4, "xixi").start();
        new Thread(myThread4, "hehe").start();

    }

}
//多个线程操作同一个资源时，线程不安全，数据紊乱
/*
haha拿到了第9张票
xixi拿到了第8张票
hehe拿到了第10张票
hehe拿到了第6张票
xixi拿到了第7张票
haha拿到了第5张票
hehe拿到了第4张票
haha拿到了第4张票
xixi拿到了第4张票
xixi拿到了第2张票
hehe拿到了第3张票
haha拿到了第1张票
 */

实现Callable接口

可以定义返回值、可以抛出异常

import org.apache.commons.io.FileUtils;

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

public class MyCallable implements Callable<Boolean> {

    private String url;
    private String name;

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

    @Override
    public Boolean call() throws Exception {
        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 {
        MyCallable t1 = new MyCallable("https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=3246675119,2528014287&fm=26&gp=0.jpg", "csgo1.jpg");
        MyCallable t2 = new MyCallable("https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=3246675119,2528014287&fm=26&gp=0.jpg", "csgo2.jpg");
        MyCallable t3 = new MyCallable("https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=3246675119,2528014287&fm=26&gp=0.jpg", "csgo3.jpg");

        //创建执行服务
        ExecutorService ser = Executors.newFixedThreadPool(3);

        //提交执行
        Future<Boolean> r1 = ser.submit(t1);
        Future<Boolean> r2 = ser.submit(t2);
        Future<Boolean> r3 = ser.submit(t3);

        //获取结果
        boolean rs1 = r1.get();
        boolean rs2 = r2.get();
        boolean rs3 = r3.get();

        //关闭服务
        ser.shutdown();
    }


}

class WebDownloader{
    public void downloader(String url, String name){
        try {
            FileUtils.copyURLToFile(new URL(url), new File(name));
        } catch (IOException e) {
            e.printStackTrace();
            System.out.println("downloader异常");
        } finally {
        }
    }
}

静态代理

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
代理对象可以做很多真实对象做不了的事情
真实对象专注做自己的事情

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

        You you = new You();

        //代理真实对象runnable
        new Thread(()-> System.out.println("haha")).start();
        
        //代理真实对象you
        new WeddingCompany(new You()).HappyMarry();

        WeddingCompany weddingCompany = new WeddingCompany(you);
        weddingCompany.HappyMarry();
    }
}

interface Marry{
    void HappyMarry();
}

//真实角色
class You implements Marry{
    @Override
    public void HappyMarry() {
        System.out.println("marry!");
    }
}

//代理角色
class WeddingCompany implements Marry{
    
    private Marry target;

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

    @Override
    public void HappyMarry() {
        before();
        this.target.HappyMarry();//真实对象
        after();
    }


    public void before() {
        System.out.println("before marry");
    }
    public void after() {
        System.out.println("after marry");
    }
}

posted @ 2021-03-13 19:42 n1ce2cv 阅读(211) 评论(0) 编辑收藏举报

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java线程实现的三种方式以及静态代理

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