1. java对象结构查看-JOL

描述：openjdk提供的一个查看java对象的小工具
官网：jol官网链接
基本用法：

• 引入maven

        <!-- https://mvnrepository.com/artifact/org.openjdk.jol/jol-core -->
        <dependency>
            <groupId>org.openjdk.jol</groupId>
            <artifactId>jol-core</artifactId>
            <version>0.10</version>
        </dependency>

• 打印对象

public static void main(String[] args) {
        Object obj = new Object();
        System.out.println(ClassLayout.parseInstance(obj).toPrintable());
    }

• 查看结果

java.lang.Object object internals:
 OFFSET  SIZE   TYPE DESCRIPTION                               VALUE
      0     4        (object header)                           01 00 00 00 (00000001 00000000 00000000 00000000) (1)
      4     4        (object header)                           00 00 00 00 (00000000 00000000 00000000 00000000) (0)
      8     4        (object header)                           28 0f 96 16 (00101000 00001111 10010110 00010110) (378933032)
     12     4        (loss due to the next object alignment)
Instance size: 16 bytes
Space losses: 0 bytes internal + 4 bytes external = 4 bytes total

（持续更新......）