JAVA并发编程5

说明：先上代码，笔记后续补充。
public class LockTest1 {
    /**
     * 锁嵌套会出现死锁
     *  避免 1.尽量不要写锁的嵌套   2.锁嵌套的顺序（都调用getLock方法）   3.引入超时机制
     */
    //显示锁Lock，可重入锁
    //可中断锁，Lock就是，可以中断的
    //公平锁，synchronized是随机锁，不公平
    //乐观锁，悲观锁 数据库层面
    Lock lock = new ReentrantLock();

    /**
     * 读 上readerLock  写上WriteLock
     */
    ReentrantReadWriteLock readWriteLock = new ReentrantReadWriteLock();

    //锁  locka    lockb
    private Object locka = new Object();
    private Object lockb = new Object();

    public static void main(String[] args) {
        new LockTest1().deadLock();
    }
    /**
     * 嵌套锁
     */
    private void deadLock(){
        Thread thread1 = new Thread(new Runnable() {
            @Override
            public void run() {
                getLock();
//                synchronized (locka){
//                    try {
//                        System.out.println(Thread.currentThread().getName()+"获取A锁！");
//                        Thread.sleep(500);
//                        System.out.println(Thread.currentThread().getName()+"睡眠500ms");
//                    } catch (InterruptedException e) {
//                        e.printStackTrace();
//                    }
//                    System.out.println(Thread.currentThread().getName()+"需要B锁");
//                    synchronized (lockb){
//                        System.out.println(Thread.currentThread().getName()+"B锁中！");
//                    }
//                }
            }
        },"thread1");

        Thread thread2 = new Thread(new Runnable() {
            @Override
            public void run() {
                getLock();
//                synchronized (lockb){
//                    try {
//                        System.out.println(Thread.currentThread().getName()+"获取B锁！");
//                        Thread.sleep(500);
//                        System.out.println(Thread.currentThread().getName()+"睡眠500ms");
//                    } catch (InterruptedException e) {
//                        e.printStackTrace();
//                    }
//                    System.out.println(Thread.currentThread().getName()+"需要A锁");
//                    synchronized (locka){
//                        System.out.println(Thread.currentThread().getName()+"A锁中！");
//                    }
//                }
            }
        },"thread2");

        thread1.start();
        thread2.start();
    }

    public void getLock(){
        synchronized (locka){
            try {
                System.out.println(Thread.currentThread().getName()+"获取A锁！");
                Thread.sleep(500);
                System.out.println(Thread.currentThread().getName()+"睡眠500ms");
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName()+"需要B锁");
            synchronized (lockb){
                System.out.println(Thread.currentThread().getName()+"B锁中！");
            }
        }
    }
}