Unsafe对象的创建

Unsafe对象提供了非常底层的，操作内存、线程的方法，Unsafe对象不能直接调用，只能通过反射获得。

public Class UnsafeAccessor{
    static Unsafe unsafe;
    
    static{
        try{
            Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
            theUnsafe.setAccessible(true);
            unsafe = (Unsafe) theUnsafe.get(null);
        }catch(NoSuchFieldException | IllegalAccessException e){
            throw new Error(e);
        }
    }
    
    static Unsafe getUnsafe(){
        return unsafe;
    }
}