详解JUC并发编程之锁

  public static void main(String[] args) {
        StringBuffer buffer = new StringBuffer();
        buffer.append("a");
        buffer.append("b");
        buffer.append("c");
        System.out.println("拼接之后的结果是:>>>>>>>>>>>"+buffer);
    }

  @Override
    @IntrinsicCandidate
    public synchronized StringBuffer append(String str) {
        toStringCache = null;
        super.append(str);
        return this;
    }

package com.xiaojie.juc.thread.lock;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
/**
 * @author xiaojie
 * @version 1.0
 * @description: 测试锁的重入性
 * @date 2021/12/30 22:09
 */
public class Test01 {
    public synchronized void a() {
        System.out.println(Thread.currentThread().getName() + "运行a方法");
        b();
    }
    private synchronized void b() {
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(Thread.currentThread().getName() + "运行b方法");
    }
    public static void main(String[] args) {
        Test01 test01 = new Test01();
        ExecutorService executorService = Executors.newFixedThreadPool(3);
        for (int i=0;i<10;i++){
            executorService.execute(() -> test01.a());
        }
    }
}

package com.xiaojie.juc.thread.lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
/**
 * @description: 读写锁验证共享锁和独占锁
 * @author xiaojie
 * @date 2021/12/30 23:28
 * @version 1.0
 */
public class ReadAndWrite {
    static class ReadThred extends Thread {
        private ReentrantReadWriteLock lock;
        private String name;
        public ReadThred(String name, ReentrantReadWriteLock lock) {
            super(name);
            this.lock = lock;
        }
        @Override
        public void run() {
            try {
                lock.readLock().lock();
                System.out.println(Thread.currentThread().getName() + "这是共享锁。。。。。。");
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                lock.readLock().unlock();
                System.out.println(Thread.currentThread().getName() + "释放锁成功。。。。。。");
            }
        }
    }
    static class WriteThred extends Thread {
        private ReentrantReadWriteLock lock;
        private String name;
        public WriteThred(String name, ReentrantReadWriteLock lock) {
            super(name);
            this.lock = lock;
        }
        @Override
        public void run() {
            try {
                lock.writeLock().lock();
                Thread.sleep(3000);
                System.out.println(Thread.currentThread().getName() + "这是独占锁。。。。。。。。");
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                lock.writeLock().unlock();
                System.out.println(Thread.currentThread().getName() + "释放锁。。。。。。。");
            }
        }
    }
    public static void main(String[] args) {
        ReentrantReadWriteLock reentrantReadWriteLock = new ReentrantReadWriteLock();
        ReadThred readThred1 = new ReadThred("read-thread-1", reentrantReadWriteLock);
        ReadThred readThred2 = new ReadThred("read-thread-1", reentrantReadWriteLock);
        WriteThred writeThred1 = new WriteThred("write-thread-1", reentrantReadWriteLock);
        WriteThred writeThred2 = new WriteThred("write-thread-2", reentrantReadWriteLock);
        readThred1.start();
        readThred2.start();
        writeThred1.start();
        writeThred2.start();
    }
}