Java中的Unsafe工具类使用详解

public static void main(String[] args) throws Exception{
    Class<Unsafe> unsafeClass = Unsafe.class;
    //方法一：通过反射构造一个Unsafe对象
    Constructor<Unsafe> constructor = unsafeClass.getDeclaredConstructor();
    constructor.setAccessible(true);
    Unsafe unsafe1 = constructor.newInstance();
    System.out.println(unsafe1);
    //方法二：获取内部静态成员变量
    Field theUnsafe = unsafeClass.getDeclaredField("theUnsafe");
    theUnsafe.setAccessible(true);
    Unsafe unsafe2 = (Unsafe) theUnsafe.get(null);
    System.out.println(unsafe2);
}

import sun.misc.Unsafe;
import java.lang.reflect.*;
public class UnsafeDemo {
    public static void main(String[] args) throws Exception {
        Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
        theUnsafe.setAccessible(true);
        Unsafe unsafe = (Unsafe) theUnsafe.get(null);
        User user = new User("jsbintask");
        long nameOffset = unsafe.objectFieldOffset(User.class.getDeclaredField("name"));
        boolean res1 = unsafe.compareAndSwapObject(user, nameOffset, "jsbintask1", "jsbintask2");
        System.out.println(res1+", 第一次更新后的值：" + user.getName());
        boolean res2 = unsafe.compareAndSwapObject(user, nameOffset, "jsbintask", "jsbintask2");
        System.out.println(res2+", 第二次更新后的值：" + user.getName());
    }
    public static class User {
        private String name;
            public User(String name) {
            this.name = name;
        }
        public String getName() {
            return name;
        }
    }  
}