Java进阶（锁）——锁的升级，synchronized与lock锁区别

引出

Java进阶（锁）——锁的升级，synchronized与lock锁区别

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Java中锁升级

看一段代码：

public class App {
   
    public static void main(String[] args) throws InterruptedException {
   
        Calculate cal = new Calculate();
        long start = System.currentTimeMillis();
        Thread t1 = new Thread(()->{
   
            for (int i = 0; i < 1000_0000; i++) {
   
                cal.increase();
            }
        });
        Thread t2 = new Thread(()->{
   
            for (int i = 0; i < 1000_0000; i++) {
   
                cal.increase();
            }
        });
        t1.start();
        t2.start();
        t1.join();
        t2.join();
        System.out.println("time = " + (System.currentTimeMillis()-start));
        System.out.println("cal.getNum() = " + cal.getNum(