JavaSE进阶知识学习----多线程JUC高级知识-4

本文介绍了Java中读写锁ReadWriteLock的概念及其应用场景,通过示例代码展示了读写锁如何实现读写分离,提高并发性能。同时,文章还探讨了线程锁的八种常见情况,并解释了非静态与静态同步方法锁的区别。

摘要生成于 C知道 ,由 DeepSeek-R1 满血版支持, 前往体验 >

9.ReadWriteLock读写锁

说明:写写/读写需要‘互斥’,读读不需要‘互斥’。不能一存在线程问题就加锁,读就不需要锁,所以才有了读写分离的读写锁ReadWriteLock。
是一个接口,位于java.util.concurrent.locks包下。有两个方法

Lock readLock() 返回用于读取操作的锁。
Lock writeLock() 返回用于写入操作的锁。

实例如下:

public class TestReadWriteLock {
    public static void main(String[] args) {
        final ReadWriteLockDemo rw = new ReadWriteLockDemo();
        new Thread(new Runnable() {

            @Override
            public void run() {
                rw.set((int)(Math.random()*10));

            }
        },"写线程").start();
        for(int i = 0; i< 5; i++){
            new Thread(new Runnable() {

                @Override
                public void run() {
                    rw.get();
                }
            },"读操作").start();
        }
    }

}
class ReadWriteLockDemo{
    private int number = 0;
    private ReadWriteLock lock = new ReentrantReadWriteLock();
    //读操作
    public void get(){
        lock.readLock().lock();//上锁
        try{
            System.out.println(Thread.currentThread().getName()+":"+number);
        }finally{
            lock.readLock().unlock();//释放锁
        }

    }
    //写操作
    public void set(int number){
        lock.writeLock().lock();
        try{
            System.out.println(Thread.currentThread().getName());
            this.number = number;
        }finally{
            lock.writeLock().unlock();
        }

    }
}

10.线程八锁

如下实例:

1.两个普通同步方法,两个线程,标准打印,结果:one two
public class TestThread8Monitor {
    public static void main(String[] args) {
        final Number number = new Number();

        new Thread(new Runnable() {
            @Override
            public void run() {
                number.getOne();
            }
        }).start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                number.getTwo();
            }
        }).start();
    }
}
class Number{
    public synchronized void getOne(){
        System.out.println("one");
    }
    public synchronized void getTwo(){
        System.out.println("Two");
    }
}
2.新增Thread.sleep()给getOne(),结果:one two
public class TestThread8Monitor {
    public static void main(String[] args) {
        final Number number = new Number();

        new Thread(new Runnable() {
            @Override
            public void run() {
                number.getOne();
            }
        }).start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                number.getTwo();
            }
        }).start();
    }
}
class Number{
    public synchronized void getOne(){
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("one");
    }
    public synchronized void getTwo(){
        System.out.println("Two");
    }
}
3.新增普通方法getThree(),结果:three one two
public class TestThread8Monitor {
    public static void main(String[] args) {
        final Number number = new Number();

        new Thread(new Runnable() {
            @Override
            public void run() {
                number.getOne();
            }
        }).start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                number.getTwo();
            }
        }).start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                number.getThree();
            }
        }).start();
    }
}
class Number{
    public synchronized void getOne(){
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("one");
    }
    public synchronized void getTwo(){
        System.out.println("Two");
    }
    public void getThree(){
        System.out.println("Three");
    }
}
4.两个普通同步方法,两个对象,结果:two one
public class TestThread8Monitor {
    public static void main(String[] args) {
        final Number number1 = new Number();
        final Number number2 = new Number();

        new Thread(new Runnable() {
            @Override
            public void run() {
                number1.getOne();
            }
        }).start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                number2.getTwo();
            }
        }).start();

    }
}
class Number{
    public synchronized void getOne(){
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("one");
    }
    public synchronized void getTwo(){
        System.out.println("Two");
    }
}
5.修改getOne()为静态同步方法,结果:two one
public class TestThread8Monitor {
    public static void main(String[] args) {
        final Number number1 = new Number();
        final Number number2 = new Number();

        new Thread(new Runnable() {
            @Override
            public void run() {
                number1.getOne();
            }
        }).start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                number2.getTwo();
            }
        }).start();

    }
}
class Number{
    public static synchronized void getOne(){
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("one");
    }
    public synchronized void getTwo(){
        System.out.println("Two");
    }
}
6.修改两个方法均为静态同步方法,一个对象,结果:one two
public class TestThread8Monitor {
    public static void main(String[] args) {
        final Number number1 = new Number();

        new Thread(new Runnable() {
            @Override
            public void run() {
                number1.getOne();
            }
        }).start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                number1.getTwo();
            }
        }).start();

    }
}
class Number{
    public static synchronized void getOne(){
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("one");
    }
    public static synchronized void getTwo(){
        System.out.println("Two");
    }
}
7.一个静态同步方法,一个非静态同步方法,两个对象,结果:two one
public class TestThread8Monitor {
    public static void main(String[] args) {
        final Number number1 = new Number();
        final Number number2 = new Number();

        new Thread(new Runnable() {
            @Override
            public void run() {
                number1.getOne();
            }
        }).start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                number2.getTwo();
            }
        }).start();

    }
}
class Number{
    public static synchronized void getOne(){
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("one");
    }
    public  synchronized void getTwo(){
        System.out.println("Two");
    }
}
8.两个静态同步方法,两个对象,结果:one two
public class TestThread8Monitor {
    public static void main(String[] args) {
        final Number number1 = new Number();
        final Number number2 = new Number();

        new Thread(new Runnable() {
            @Override
            public void run() {
                number1.getOne();
            }
        }).start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                number2.getTwo();
            }
        }).start();

    }
}
class Number{
    public static synchronized void getOne(){
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("one");
    }
    public static synchronized void getTwo(){
        System.out.println("Two");
    }
}

以上就是线程的八种常见的情况,线程八锁的关键在于:
1. 非静态方法的锁默认为this,静态方法的锁为对应的class实例(这里是NUmber.class)
2. 某一个时刻内,只能有一个线程持有锁,无论有几个方法

评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值