多线程详解1

Thread

创建线程方式1

继承Thread类

子类继承Thread类具备多线程能力

启动线程：子类对象.start()

不建议使用：避免OOP单继承局限性

//创建线程方式1：继承Thread类，重写run()方法，调用start开启线程
//线程开启不一定立即执行，由cpu调度
public class TestThread1 extends Thread{
    @Override
    public void run() {
        //run方法线程体
        for (int i = 0; i < 20; i++) {
            System.out.println("我在看代码");
        }
    }

    public static void main(String[] args) {
        //main线程，主线程
        //创建一个线程对象
        TestThread1 testThread1 = new TestThread1();
        //调用start方法开启线程
        testThread1.start();
        for (int i = 0; i < 200; i++) {
            System.out.println("我在学习多线程");
        }
    }
}

网图下载

//要导入commons-io
import org.apache.commons.io.FileUtils;

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

//练习Thread，实现多线程同步下载图片
public class TestThread2 extends Thread{
    private String url;//网络图片地址
    private String name;//保存的文件名

    public TestThread2(String url, String name) {
        this.url = url;
        this.name = name;
    }

    @Override
    public void run() {//下载图片线程的执行体
        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) {
        TestThread2 t1= new TestThread2("https://ss1.bdstatic.com/70cFuXSh_Q1YnxGkpoWK1HF6hhy/it/u=976577053,714354874&fm=26&gp=0.jpg","1.jpg");
        TestThread2 t2 = new TestThread2("https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fb-ssl.duitang.com%2Fuploads%2Fitem%2F201810%2F05%2F20181005014913_uwpqy.jpg&refer=http%3A%2F%2Fb-ssl.duitang.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=jpeg?sec=1624010560&t=062a7d0f6d5b657f0bbea623c03cfedb","2.jpg");
        TestThread2 t3= new TestThread2("https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fi0.hdslb.com%2Fbfs%2Farticle%2F6de7e33bf1e0229c2822f33699cc885199dea90f.jpg&refer=http%3A%2F%2Fi0.hdslb.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=jpeg?sec=1624010639&t=97c19ba335a8e64a239509779fa240d0","3.jpg");
        t1.start();
        t2.start();
        t3.start();
    }
}
//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方法出现异常");
        }
    }
}

//改成实现runnable接口
import org.apache.commons.io.FileUtils;

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

//练习Thread，实现多线程同步下载图片
public class TestThread2 implements Runnable {
    private String url;//网络图片地址
    private String name;//保存的文件名

    public TestThread2(String url, String name) {
        this.url = url;
        this.name = name;
    }

    @Override
    public void run() {//下载图片线程的执行体
        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) {
        TestThread2 t1= new TestThread2("https://ss1.bdstatic.com/70cFuXSh_Q1YnxGkpoWK1HF6hhy/it/u=976577053,714354874&fm=26&gp=0.jpg","1.jpg");
        TestThread2 t2 = new TestThread2("https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fb-ssl.duitang.com%2Fuploads%2Fitem%2F201810%2F05%2F20181005014913_uwpqy.jpg&refer=http%3A%2F%2Fb-ssl.duitang.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=jpeg?sec=1624010560&t=062a7d0f6d5b657f0bbea623c03cfedb","2.jpg");
        TestThread2 t3= new TestThread2("https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fi0.hdslb.com%2Fbfs%2Farticle%2F6de7e33bf1e0229c2822f33699cc885199dea90f.jpg&refer=http%3A%2F%2Fi0.hdslb.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=jpeg?sec=1624010639&t=97c19ba335a8e64a239509779fa240d0","3.jpg");
        new Thread(t1).start();
        new Thread(t2).start();
        new Thread(t3).start();
    }
}
//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方法出现异常");
        }
    }
}

创建线程方式2

实现runnable接口

实现接口Runnable具有多线程能力

启动线程：传入目标对象+Thread对象.start()

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

//创建线程方式2：实现runnable接口，重写run方法，执行线程需要丢入runna接口实现类，调用start方法
public class TestThread3 implements Runnable{
    @Override
    public void run() {
        for (int i = 0; i < 200; i++) {
            System.out.println("我在看代码");
        }
    }

    public static void main(String[] args) {
        //创建runnable接口的实现类对象
        TestThread3 testThread3 = new TestThread3();
        //创建线程对象，通过线程对象来开启我们的线程，代理
//        Thread thread = new Thread(testThread3);
//        thread.start();
        new Thread(testThread3).start();
        for (int i = 0; i < 200; i++) {
            System.out.println("我在学习多线程");
        }
    }


}

龟兔赛跑

//模拟龟兔赛跑
public class Race implements Runnable{
    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 = ganmeOver(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 ganmeOver(int steps){
        //判断是否有胜利者
        if(winner!=null){//已经存在胜利者了
            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();
    }
}

静态代理模式

//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
public class StaticProxy {
    public static void main(String[] args) {
        WeddingCompany weddingCompany = new WeddingCompany(new You());
        weddingCompany.HappyMarry();
    }
}
    interface Marry{
        void HappyMarry();
    }
    //真实角色，你去结婚
    class You implements Marry{

        @Override
        public void HappyMarry() {
            System.out.println("要结婚了，超开心");
        }
    }
    //代理角色，帮助你结婚
    class WeddingCompany implements Marry{
        private Marry target;

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

        @Override
        public void HappyMarry() {
            before();
            this.target.HappyMarry();
            after();
        }

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

        private void before() {
            System.out.println("结婚前布置现场");
        }
    }

Lambda表达式

//推导lambda表达式
public class TestLambda1 {
    //静态内部类
    static class Like2 implements ILike{
        @Override
        public void lambda() {
            System.out.println("i like lambda2");
        }
    }

    public static void main(String[] args) {
        ILike like = new Like();
        like.lambda();
        like = new Like2();
        like.lambda();
        //局部内部类
        class Like3 implements ILike{
            @Override
            public void lambda() {
                System.out.println("i like lambda3");
            }
        }
       like = new Like3();
       like.lambda();

        //匿名内部类,没有类的名称，必须借助接口或者父类
        like = new ILike() {
            @Override
            public void lambda() {
                System.out.println("i like lambda4");
            }
        };
        like.lambda();

        //用lambda简化
        like = () ->{
            System.out.println("i like lambda5");
        };
        like.lambda();
    }
}
//定义一个函数是接口
interface ILike{
    void lambda();
}
//实现类
class Like implements ILike{
    @Override
    public void lambda() {
        System.out.println("i like lambda");
    }
}

public class TestLambda2 {

    public static void main(String[] args) {
        //lambda表达式简化
        ILove love =(int a)-> {
            System.out.println("I love you-->"+a);
        };
        //简化1.去掉参数值的类型
        love = (a)-> {
            System.out.println("I love you-->"+a);
        };
        //简化2.简化括号
        love = a-> {
            System.out.println("I love you-->"+a);
        };
        //简化3.去掉花括号
        love  = a->System.out.println("I love you-->"+a);
        //总结：
        //lambda表达式只能有一行代码的情况下才能简化成一行，如果有多行，那么就用代码块包裹
        //前提是接口为函数式接口
        //多个参数也可以去掉参数类型，要去掉就都去掉，必须加上括号
        love.love(2);
    }
}
interface ILove{
    void love(int a);
}

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原文地址：https://www.cnblogs.com/asako/p/14787417.html