Java不能直接訪問作業系統底層，而是通過本地方法來訪問。Unsafe類提供了硬體級別的原子操作,在java中記憶體中的物件地址是可變的，所以獲得的記憶體地址有可能會變化。要獲得記憶體地址也只能通過Unsafe的方法來獲得,下面類提供了獲取java物件記憶體地址的方法

package com.example.demo.othertest;
import java.lang.reflect.Field;
import sun.misc.Unsafe;

public class Addresser {
    private static Unsafe unsafe;

    static {
        try {
            Field field = Unsafe.class.getDeclaredField("theUnsafe");
            field.setAccessible(true);
            unsafe = (Unsafe) field.get(null);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static long addressOf(Object o) throws Exception {

        Object[] array = new Object[] { o };

        long baseOffset = unsafe.arrayBaseOffset(Object[].class);
        //arrayBaseOffset方法是一個本地方法，可以獲取陣列第一個元素的偏移地址
        int addressSize = unsafe.addressSize();
        long objectAddress;
        switch (addressSize) {
            case 4:
                objectAddress = unsafe.getInt(array, baseOffset);
                //getInt方法獲取物件中offset偏移地址對應的int型field的值
                break;
            case 8:
                objectAddress = unsafe.getLong(array, baseOffset);
                //getLong方法獲取物件中offset偏移地址對應的long型field的值
                break;
            default:
                throw new Error("unsupported address size: " + addressSize);
        }
        return (objectAddress);
    }

    public static void main(String... args) throws Exception {
        Object mine = "Hello world".toCharArray(); //先把字串轉化為陣列物件
        long address = addressOf(mine);
        System.out.println("Addess: " + address);

        // Verify address works - should see the characters in the array in the output
        printBytes(address, 27);
    }

    public static void printBytes(long objectAddress, int num) {
        for (long i = 0; i < num; i++) {
            int cur = unsafe.getByte(objectAddress + i);
            System.out.print((char) cur);
        }
        System.out.println();
    }
}