线程

线程

多任务

多线程

继承Thread 类

package org.Demo01;


//创建线程方式一：继承thread类，重写run()犯法，调用Start开启线程

//总结：注意：线程开启不一定立即执行，由cpu调度执行
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---"+i);
        }
    }

    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 < 20; i++) {
            System.out.println("我在学习多线程--"+i);
        }
    }



}

案例：

package org.Demo01;

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;
    }
    //下载图片线程的执行体
    @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) {
        TestThread2 t1 = new TestThread2("https://i-blog.csdnimg.cn/blog_migrate/673f129961a809060a2d5f1dcca3b8f8.png","1.jpg");
        TestThread2 t2 = new TestThread2("https://i-blog.csdnimg.cn/blog_migrate/673f129961a809060a2d5f1dcca3b8f8.png","2.jpg");
        TestThread2 t3 = new TestThread2("https://i-blog.csdnimg.cn/blog_migrate/673f129961a809060a2d5f1dcca3b8f8.png","3.jpg");

        //先下载t1，t2，t3，但是最后执行的结果是不一样的
        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方法出现问题");
        }
    }
}

实现Runnable

package org.Demo01;

//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runnable接口实现类。调用start方法。
public class TestThread3 implements Runnable{
    @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---"+i);
        }
    }

    public static void main(String[] args) {

//        //创建一个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 < 20; i++) {
            System.out.println("我在学习多线程--"+i);
        }
    }
}

小结

买火车票的例子

//存在安全隐患

package org.Demo01;

//多个线程同时操作同一个对象
//买火车票例子

//发现问题：多个线程操作同一个资源的情况下，线程不安全，数据紊乱
public class Testthread4 implements Runnable{

    //票数
    int ticketNums = 10;

    @Override
    public void run() {
        while(true){

            if(ticketNums<=0){
                break;
            }
            //模拟延时
            try {
                Thread.sleep(200);
            } catch (Exception e) {
                e.printStackTrace();
            }

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

案例：龟兔赛跑

package org.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(5);
                }catch (InterruptedException e){
                e.printStackTrace();
            }}

            //判断比赛是否结束
            boolean flag = gameOver(i);
            //如果比赛结束了就提停止程序
            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){
        //判断是否有胜利者
        if (winner!=null){
            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

package org;

import java.nio.file.attribute.FileStoreAttributeView;

//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();//你要结婚

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

       new WeddingCompany(new You()).HappyMarry();
        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("老四要结婚惹，超开心");
    }
}

//代理结婚，帮助你结婚
class  WeddingCompany implements Marry{
    //代理谁-->真实目标角色
    private Marry target;

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

    @Override
    public void HappyMarry() {
        this.target.HappyMarry();//这就是真实对象
        after();
    }
    private void after(){
        System.out.println("结婚之前，布置现场");
    }
    private void before(){
        System.out.println("结婚之后，收尾款");
    }

}

Lamda表达式

总结 ：

1. lambda表达式只能有一行代码的情况下才能简化为一行，如果有多行，那么就用代码块包裹
2. 前提是接口为函数式接口
3. 多个参数也可以去掉参数类型，要去掉就都去掉必须加括号

线程停止

package org.state;
//测试stop
//1.建议线程正常停止-->利用次数，不建议死循环
//2.建议使用标志位-->设置一个标志位
//3.不要使用stop或者destroy等过时或者JDK不建议使用的方法
public class TestStop implements Runnable{

    //1.设置一个标志位
    private boolean flag = true;
    @Override
    public void run() {
       int i = 0;
       while (flag){
           System.out.println("run....Thread"+i++);
       }
    }

    //2.设置一个公开的方法停止线程，转换标志位
    public void stop(){
        this.flag = false;
    }
    public static void main(String[] args) {
    TestStop testStop = new TestStop();

    new Thread(testStop).start();

        for (int i = 0; i < 1000; i++) {
            System.out.println("main"+ i);
            if (i==900){
                //调用stop方法切换标志位，让线程停止
                testStop.stop();
                System.out.println("线程该停止了");
            }
        }
    }
}

线程休眠

1000毫秒=1秒

```java
package org.state;

import java.text.SimpleDateFormat;
import java.util.Date;

//模拟倒计时
public class TestSleep {

    public static void main(String[] args) {
        //打印当前系统时间
        //获取系统当前时间
        Date startTime = new Date(System.currentTimeMillis());

        while(true){
            try{
                Thread.sleep(1000);
                System.out.println(new SimpleDateFormat("HH:mm:ss").format(startTime));
                startTime = new Date(System.currentTimeMillis());//更新当前时间
            }catch (InterruptedException e){
                e.printStackTrace();
            }
        }
    }
    //模拟倒计时
    public static void tenDown() throws InterruptedException {
        int num = 10;
        while (true){
            Thread.sleep(1000);
            System.out.println(num--);
            if (num<=0){
                break;
            }

        }
    }

}

```

线程礼让

yield（礼让）

​

package org.state;

//测试礼让线程
//礼让不一定成功。看cpu心情
public class TestYield {
    public static void main(String[] args) {
        MyYield myYield = new MyYield();
        new Thread(myYield,"A").start();
        new Thread(myYield,"B").start();
    }

}

class  MyYield implements Runnable{
    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName()+"线程开始执行");
        //Thread.yield();//礼让

        System.out.println(Thread.currentThread().getName()+"线程停止执行");
    }
}

线程强制执行

package org.state;
//测试join方法，想象为插队
public class TestJoin implements Runnable{
    @Override
    public void run() {
        for (int i = 0; i < 1000; i++) {
            System.out.println("VIP来咯"+i);
        }
    }

    public static void main(String[] args) throws InterruptedException {
        //启动我们的线程
        TestJoin testJoin = new TestJoin();
        Thread thread = new Thread(testJoin);
        thread.start();

        //主线程
        for (int i = 0; i < 500; i++) {
            if (i==200){
                thread.join();//插队
            }
            System.out.println("main"+i);
        }

    }
}

线程状态观测

线程的五种状态：新生，就绪，运行，阻塞，死亡

package org.state;
//观察测试线程的状态
public class TestState {


    public static void main(String[] args) throws InterruptedException {
        Thread thread = new Thread(() -> {
            for (int i = 0; i < 5; i++) {
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            System.out.println("/////////");
        });

        //观察状态
        Thread.State state = thread.getState();
        System.out.println(state);//new

        //观察启动后
        thread.start();
        state = thread.getState();
        System.out.println(state);//Run

        while (state != Thread.State.TERMINATED) {//只要线程不终止就一直输出对象
            Thread.sleep(100);
            state = thread.getState();//更新线程状态
            System.out.println(state);//输出线程状态


        }

    }
}

线程的优先级

package org.state;
//测试线程优先级
public class TestPriority {

    public static void main(String[] args) {
        //主线程的默认优先级
        System.out.println(Thread.currentThread().getName()+"-->"+Thread.currentThread().getPriority());

        MyPriority myPriority = new MyPriority();

        Thread t1 = new Thread(myPriority);
        Thread t2 = new Thread(myPriority);
        Thread t3 = new Thread(myPriority);
        Thread t4 = new Thread(myPriority);
        Thread t5 = new Thread(myPriority);
        Thread t6 = new Thread(myPriority);

        //先设置优先级，在启动
        t1.start();

        t2.setPriority(1);
        t2.start();

        t3.setPriority(4);
        t3.start();

        t4.setPriority(Thread.MAX_PRIORITY);//10
        t4.start();

        t5.setPriority(8);
        t5.start();

        t6.setPriority(7);
        t6.start();
    }
}

class MyPriority implements Runnable{

    @Override()
    public void run() {
        System.out.println(Thread.currentThread().getName()+"-->"+Thread.currentThread().getPriority());
    }
}

守护线程

用户线程：main（）

守护线程：gc（）

package org.state;

//测试守护线程：上帝守护你
public class TestDaemon {
    public static void main(String[] args) {
        God god = new God();
        YOU you = new YOU();


        Thread thread = new Thread(god);
        thread.setDaemon(true);//默认false表示用户线程，正常的线程都是用户线程

        thread.start();//上帝守护线程启动

        new Thread(you).start();
    }

}


//上帝
class God implements Runnable{

    @Override
    public void run() {
        while (true){
            System.out.println("上帝保佑着你");
        }
    }
}

//你
class YOU implements Runnable{

    @Override
    public void run() {
        for (int i = 0; i < 36500; i++) {
            System.out.println("你一生都开心的活着00");
        }
        System.out.println("=====goodbye!world");
    }
}

线程同步

多个线程操作同一个资源

不安全的买票

package org.syn;
//不安全的买票
//线程不安全，有负数
public class UnsafeBuyTicket {

    public static void main(String[] args) {
        BuyTicket station = new BuyTicket();

        new Thread(station,"苦逼的我").start();
        new Thread(station,"牛逼的你").start();
        new Thread(station,"邪恶黄牛").start();
    }
}

class BuyTicket implements Runnable{

    //票
    int ticketNums = 10;
    boolean flag = true;//外部停止方式

    @Override
    public void run() {
        //买票
        while(flag){
         buy();
        }
    }

    private void buy(){
        //判断是否有票
        if(ticketNums<= 0 ){
            flag = false;
            return;
        }
        System.out.println(Thread.currentThread().getName()+"拿到"+ticketNums--);
    }
}

将这个synchronized加上就是安全的

不安全的取钱

package org.syn;

import javax.script.ScriptContext;

//不安全的取钱
//两个人去银行取钱，账户
public class UnsafeBank {

    public static void main(String[] args) {
        //账户
        Account account = new Account(100,"结婚基金");

        Drawing you = new Drawing(account,50,"你");
        Drawing girlFriend = new Drawing(account,100,"girlFriend");

        you.start();
        girlFriend.start();

    }
}

//账号
class Account{
    int money;//余额
    String name;//卡名

    public Account(int money,String name){
        this.money = money;
        this.name = name;
    }

}

//银行：模拟取款
class Drawing extends Thread{
    Account account;//账户
    //去了多少钱
    int drawingMoney;
    //现在手里有多少钱
    int nowMoney;

    public Drawing(Account account,int drawingMoney,String name){
        super(name);
        this.account = account;
        this.drawingMoney = drawingMoney;
    }

    //取钱
    @Override
    public void run(){
        //判断有没有钱
        if(account.money-drawingMoney<0){
            System.out.println(Thread.currentThread().getName()+"钱不够，取不了");
            return;
        }
        //sleep可以放大问题的发生性
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }

        //卡内余额 = 余额 - 你取的钱
        account.money = account.money - drawingMoney;
        //你手里的钱
        nowMoney = nowMoney + drawingMoney;

        System.out.println(account.name + "余额为："+account.money);
//        Thread.currentThread().getName() = this.getName();
        System.out.println(this.getName()+"手里的钱："+nowMoney);
    }
}

在run加上synchronized依旧报错

因为synchronized默认锁的是this就是他本身

《不安全的取钱》修改后代码

	package org.syn;

	import javax.script.ScriptContext;

	//不安全的取钱
	//两个人去银行取钱，账户
public class UnsafeBank {

    public static void main(String[] args) {
        //账户
        Account account = new Account(100,"结婚基金");

        Drawing you = new Drawing(account,50,"你");
        Drawing girlFriend = new Drawing(account,100,"girlFriend");

        you.start();
        girlFriend.start();

    }
}

	//账号
	class Account{
    int money;//余额
    String name;//卡名

    public Account(int money,String name){
        this.money = money;
        this.name = name;
    }

	}

	//银行：模拟取款
	class Drawing extends Thread{
    Account account;//账户
    //去了多少钱
    int drawingMoney;
    //现在手里有多少钱
    int nowMoney;

    public Drawing(Account account,int drawingMoney,String name){
        super(name);
        this.account = account;
        this.drawingMoney = drawingMoney;
    }

    //取钱
    @Override
    public synchronized void run(){

        //锁的对象就是变化的量，需要增删
        synchronized (account){

            //判断有没有钱
            if(account.money-drawingMoney<0){
                System.out.println(Thread.currentThread().getName()+"钱不够，取不了");
                return;
            }
            //sleep可以放大问题的发生性
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }

            //卡内余额 = 余额 - 你取的钱
            account.money = account.money - drawingMoney;
            //你手里的钱
            nowMoney = nowMoney + drawingMoney;

            System.out.println(account.name + "余额为："+account.money);
	//        Thread.currentThread().getName() = this.getName();
            System.out.println(this.getName()+"手里的钱："+nowMoney);
        }


    }
	}

JUC，安全类型的集合

	package org.syn;

	import java.util.concurrent.CopyOnWriteArrayList;

	//测试JUC 安全类型的集合
	public class TestJUC {
    public static void main(String[] args) {
        CopyOnWriteArrayList<String> list = new CopyOnWriteArrayList<String>();
        for (int i = 0; i < 10000; i++) {
            new Thread(()->{
                list.add(Thread.currentThread().getName());
            }).start();
        }
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        System.out.println(list.size());
    }

	}

死锁

	package org.Thread;

	//死锁：多个线程互相抱着对方需要的资源，然后形成僵持
	public class DeadLock {
    public static void main(String[] args) {
        Makeup g1 = new Makeup(0,"灰姑娘");
        Makeup g2 = new Makeup(1,"白雪公主");

        g1.start();
        g2.start();
    }
	}

	//口红
	class Lipstick{

	}

	//镜子
	class Mirror{

	}

	class Makeup extends Thread{

    // 需要的资源只有一份，用static来保证只有一份
    static Lipstick lipstick = new Lipstick();
    static Mirror mirror = new Mirror();

    int choice;//选择
    String girlName;//使用化妆品的人

    Makeup(int choice,String girlName){
        this.choice = choice;
        this.girlName = girlName;
    }

    @Override
    public void run() {
        //化妆
        try {
            makeup();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
    //化妆，互相持有对方的锁需要拿到对方的资源
    private void makeup() throws InterruptedException {
        if(choice==0){
            synchronized (lipstick) {//获得口红的锁
                System.out.println(this.girlName + "获得口红的锁");
                Thread.sleep(1000);
                }
                synchronized (mirror) {//一秒钟后想获得镜子
                System.out.println(this.girlName + "获得镜子的锁");

            }
            }else{
                synchronized (mirror){//获得镜子的锁
                        System.out.println(this.girlName + "获得镜子的锁");
                        Thread.sleep(2000);
                        }
                        synchronized (lipstick) {//两秒后想获得口红的锁
                        System.out.println(this.girlName + "获得口红的锁");

                    }

        }

    }
	}

Lock(锁)

ReentrantLook：可重复锁

	package org.gaoji;

	import java.util.concurrent.locks.ReentrantLock;

	//测试Lock锁
	public class TestLock {

    public static void main(String[] args) {
        TestLock2 testLock2 = new TestLock2();

        new Thread(testLock2).start();
        new Thread(testLock2).start();
        new Thread(testLock2).start();
    }
	}


	class TestLock2 implements Runnable{
    //  票
    int ticketNums = 10;

    //定义lock锁
    private  final ReentrantLock lock = new ReentrantLock();

    @Override
    public void run() {
        while(true) {
            while (true) {

                try {
                    lock.lock();//加锁

            if (ticketNums > 0) {
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(ticketNums--);
            } else {
                break;
            }
        }finally {
                    //解锁
                    lock.unlock();
                }
                }
        }
    }
}

线程通信

线程协作：生产者消费者模式。是一种问题

生产者和消费者

管程法

	package org.gaoji;
	//测试生产者消费者问题2：信号灯法，标志位解决
	public class TestPC2 {
    public static void main(String[] args) {
        TV tv = new TV();
        new Player(tv).start();
        new Watcher(tv).start();
    }
}


	//生产者-->演员
	class Player extends Thread{
    TV tv;
    public Player(TV tv){
        this.tv = tv;
    }

    @Override
    public void run() {
        for (int i = 0; i < 20; i++) {
            if(i%2 == 0){
                this.tv.play("快乐大本营播放中");
            }else {
                this.tv.play("抖音：记录美好生活");
            }
        }
    }
}

	//消费者-->观众
	class  Watcher extends Thread{
    TV tv;
    public Watcher(TV tv){
        this.tv = tv;
    }

    @Override
    public void run() {
        for (int i = 0; i < 20; i++) {
            tv.watch();
        }
    }
}

	//产品-->节目
	class TV{
    //演员表演，观众等待 T
    //观众观看，演员等待 F
    String voice;//表演的节目
    boolean flag = true;

    //表演
    public synchronized void play(String voice){

        if(!flag){
            try {
                this.wait();
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }

        System.out.println("演员表演了："+voice);
        //通知观众观看
        this.notifyAll();//通知唤醒
        this.voice = voice;
        this.flag = !this.flag;
    }

    //观看
    public synchronized void watch(){
        if(flag){
            try {
                this.wait();
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }
        System.out.println("观看了"+voice);
        //通知演员表演
        this.notifyAll();
        this.flag = !this.flag;
    }

}

地址池

	package org.gaoji;

	import java.util.concurrent.Executor;
	import java.util.concurrent.ExecutorService;
	import java.util.concurrent.Executors;

//测试线程池
public class TestPool {

    public static void main(String[] args) {

        //1.创建服务，创建线程池
        //2.newFixedThreadPool参数为：线程池的大小
        ExecutorService service = Executors.newFixedThreadPool(10);

        service.execute(new MyThred());
        service.execute(new MyThred());
        service.execute(new MyThred());
        service.execute(new MyThred());

        //2.关闭连接
        service.shutdown();
    }
}

	class MyThred implements Runnable{
    @Override
    public void run() {
            System.out.println(Thread.currentThread().getName());
    }
}