美文网首页
JavaEE进阶知识学习----多线程JUC高级知识-4-Rea

JavaEE进阶知识学习----多线程JUC高级知识-4-Rea

作者: Waldeinsamkeit4 | 来源:发表于2018-02-25 13:13 被阅读0次

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

相关文章

网友评论

      本文标题：JavaEE进阶知识学习----多线程JUC高级知识-4-Rea

      本文链接：https://www.haomeiwen.com/subject/ggkrxftx.html

      延伸阅读

      深度阅读

      • 您也可以注册成为美文阅读网的作者，发表您的原创作品、分享您的心情！

      栏目导航

      热点阅读

      关于我们|服务条款|联系我们|JavaEE进阶知识学习----多线程JUC高级知识-4-Rea|投稿指南|网站地图|RSS订阅|排版工具|手机版

      提供经典美文摘抄,优美散文欣赏,现代诗歌精选,短篇小说,心情随笔,表白情书范文,故事会在线阅读欣赏

      Copyright © 2014-2023 Haomeiwen.com All Rights Reserved. 好美文阅读网 版权所有

      备案信息：桂公网安备 45052102000051号 · 桂ICP备13007215号-3

      本站所收录作品、热点评论等信息部分来源互联网，目的只是为了系统归纳学习和传递资讯

      所有作品版权归原创作者所有，与本站立场无关，如不慎侵犯了你的权益，请联系我们告知，我们将做删除处理！