1. public class SupkingxLock {
    2.     private static final Unsafe unsafe;
    3.     private static final long valueOffset;
    4.     private volatile int value = 0;
    6.     static {
    7.         try {
    8.             Class<Unsafe> unsafeClass = Unsafe.class;
    9.             Field theUnsafe = unsafeClass.getDeclaredField("theUnsafe");
    10.             theUnsafe.setAccessible(true);
    11.             unsafe = (Unsafe) theUnsafe.get(null);
    12.             valueOffset = unsafe.objectFieldOffset
    13.                     (SupkingxLock.class.getDeclaredField("value"));
    14.         } catch (Exception ex) {
    15.             throw new Error(ex);
    16.         }
    17.     }
    19.     public void lock() {
    20.         // 自旋
    21.         for (; ; ) {
    22.             // this 当前对象本身，valueOffset 位移偏移量，0:内存中的真值，1:将要变成的值
    23.             if (unsafe.compareAndSwapInt(this, valueOffset, 0, 1)) {
    24.                 return;
    25.             }
    26.             // 如果不是自己想要的值，则将当前线程让出去
    27.             Thread.yield();
    28.         }
    29.     }
    31.     public void unlock() {
    32.         value = 0;
    33.     }
    35.     public static void main(String[] args) {
    36.         System.out.println(unsafe);
    37.     }
    38. }