Java多线程（二）

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
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) {
        new Thread(() -> System.out.println("我爱你")).start();
        new WeddingCompany(new You()).HappyMarry();
    }
}
interface Marry {
    void HappyMarry();
}
//真实角色，去结婚
class You implements Marry {
    @Override
    public void HappyMarry() {
        System.out.println("我结婚啦！");
    }
}
//代理角色,帮助你结婚
class   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() {
        before();
        this.target.HappyMarry();//这就是真实对象
        after();
    }
    private void before() {
        System.out.println("结婚之前");
    }
    private void after() {
        System.out.println("结婚之后");
    }
}

Lambda表达式

避免匿名内部类定义过多
实质属于函数式编程概念

//推导lambda表达式
public class TestLambda {
    //2.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();
        //3.局部内部类
        class Like3 implements ILike {
            @Override
            public void lambda() {
                System.out.println("I like lambda3");
            }
        }
        like = new Like3();
        like.lambda();
        //4.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();
        //5.lambda简化
        like = () -> System.out.println("I like lambda5");
        like.lambda();
    }
}
//定义一个函数式接口
interface ILike {
    void lambda();
}
//1.实现类
class Like implements ILike {
    @Override
    public void lambda() {
        System.out.println("I like lambda");
    }
}

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，如果有多行则用代码块包裹。
2.必须是函数式接口，一个接口只能有一个方法。
3.多个参数也可以去掉参数类型，但必须都去掉，加上括号。

线程方法

停止线程

建议使用一个标志位进行终止变量，当flag=false，则终止线程运行。

//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("线程正在运行-->" + i++);
        }
    }
    //2.设置一个公开方法停止线程，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);
            //调用stop方法切换标志位，让线程停止
            if (i == 900) {
                testStop.stop();
                System.out.println("线程停止");
            }
        }
    }
}

线程休眠

sleep指定当前线程阻塞的毫秒数
sleep存在异常InterruptedException
sleep时间达到后线程进入就绪状态
sleep可以模拟网络延时，倒计时等
每一个对象都有一个锁，sleep不会释放锁

public class TestSleep implements Runnable {
    private boolean flag = true;
    @Override
    public void run() {
        int i = 10;
        System.out.println("倒计时10s");
        while (flag) {
            System.out.println(i-- + "s");
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            if (i == 0) {
                System.out.println("开炮！！！");
                stop();
            }
        }
    }
    public void stop() {
        this.flag = false;
    }
    public static void main(String[] args) {
        TestSleep testSleep = new TestSleep();
        new Thread(testSleep).start();
    }
}

线程礼让

礼让线程，让当前正在执行的线程暂停，但不阻塞
让线程从运行状态转为就绪状态
让cpu重新调度，礼让不一定成功！看CPU心情

//测试礼让线程，看CPU心情
public class TestYeild {
    public static void main(String[] args) {
        MyYeild myYeild = new MyYeild();
        new Thread(myYeild, "A").start();
        new Thread(myYeild, "B").start();
    }
}
class MyYeild implements Runnable {
    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName() + "-->运行");
        Thread.yield();
        System.out.println(Thread.currentThread().getName() + "-->停止");
    }
}

线程合并(插队)

//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("线程vip来了" + i);
        }
    }
    public static void main(String[] args) throws InterruptedException {
        TestJoin testJoin = new TestJoin();
        Thread thread = new Thread(testJoin);
        thread.start();
        //主线程
        for (int i = 0; i < 1000; i++) {
            if (i == 200) {
                thread.join();//插队
            }
            System.out.println("main" + i);
        }
    }
}

线程状态观测

线程五个状态：新生，就绪，运行，阻塞，死亡

//观察测试线程状态
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) {//只要线程不中止，就一直输出状态
            Thread.sleep(1000);
            state = thread.getState();
            System.out.println(state);
        }
    }
}

线程优先级

Java提供一个线程调度器来监控程序中启动后进入就绪状态的所有线程，线程调度器按照优先级决定应该调度哪个线程来执行
现成的优先级用数字表示，范围从1~10，设置不在范围内的值会报错
1. Thread.MINRIORITY = 1;
1. Thread.MAX_RITY = 1;
1. Thread.NORN_RITY = 1;
使用以下方式改变或获取优先级
getPriority(),setPriority(int xxx)

public class TestPriority {
    public static void main(String[] args) {
        //主线程默认优先级
        System.out.println(Thread.currentThread().getName() + "-->" + Thread.currentThread().getPriority());
        MyPriority myPriority = new MyPriority();
        Thread thread1 = new Thread(myPriority);
        Thread thread2 = new Thread(myPriority);
        Thread thread3 = new Thread(myPriority);
        Thread thread4 = new Thread(myPriority);
        Thread thread5 = new Thread(myPriority);
        Thread thread6 = new Thread(myPriority);
        //先设置优先级，再启动
        thread1.start();
        thread2.setPriority(1);
        thread2.start();
        thread3.setPriority(4);
        thread3.start();
        thread4.setPriority(10);
        thread4.start();
        thread5.setPriority(-5);
        thread5.start();
        thread6.setPriority(15);
        thread6.start();
    }
}
class MyPriority implements Runnable {
    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName() + "-->" + Thread.currentThread().getPriority());
    }
}

守护(daemon)线程

线程分为用户线程和守护线程
虚拟机必须确保用户线程执行完毕
虚拟机不用等待守护线程执行完毕
如：后台记录操作日志，监控内存，垃圾回收等待

//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 t1 = new Thread(god);
        t1.setDaemon(true);//默认为false用户线程
        t1.start();
        Thread t2 = new Thread(you);
        t2.start();
        Thread.State state = t2.getState();
        if (state == Thread.State.TERMINATED) {
            god.stop();
        } 
    }
}
//上帝
class God implements Runnable {
    private boolean flag = true;
    @Override
    public void run() {
        while (flag) {
            System.out.println("上帝保佑你");
        }
    }
    public void stop() {
        this.flag = false;
    }
}
//你
class You implements Runnable {
    @Override
    public void run() {
        for (int i = 0; i < 36500; i++) {
            System.out.println("我活了" + i + "天");
        }
        System.out.println("==GoodBye World==");
    }
}

Java多线程（二）

静态代理

Lambda表达式

线程方法

停止线程

线程休眠

线程礼让

线程合并(插队)

线程状态观测

线程优先级

守护(daemon)线程

你可能感兴趣的:(Java多线程（二）)