003--20200413学习

1、导入对象头

    <!--查看对象头-->
    <dependency>
        <groupId>org.openjdk.jol</groupId>
        <artifactId>jol-core</artifactId>
        <version>0.9</version>
    </dependency>

2、创建锁对象

package com.enzoism.springboot.lock;

/**
 * Created with IntelliJ IDEA.
 * User: enzoism
 * Date: 2020/4/14- 1:11
 */
public class LockObject {
    private boolean flag;
    private int num;
}

3、进行锁对象和查看对象头

package com.enzoism.springboot.lock;

import org.openjdk.jol.info.ClassLayout;

import java.util.concurrent.locks.ReentrantLock;

/**
 * Created with IntelliJ IDEA.
 * User: enzoism
 * Date: 2020/4/14- 1:11
 */
public class TestLock {

    static ReentrantLock lock = new ReentrantLock();
    static LockObject lockObject = new LockObject();

    public static void main(String[] args) {
//        testLock1();
//        testLock2();
        testLockAnalysis();

    }

    public static void testLock1() {
        // 使用ReentrantLock进行加锁-JUC包
        lock.lock();
        System.out.println("11111");
        System.out.println("22222");
        lock.unlock();
    }

    public static void testLock2() {
        // 使用synchronized进行加锁-JDK原生
        synchronized (lockObject) {
            System.out.println("11111");
            System.out.println("22222");
        }
    }

    public static void testLockAnalysis() {
        // 查看对象头
        System.out.println(ClassLayout.parseInstance(lockObject).toPrintable());
    }
}