开发笔记:Atomic&Unsafe

public final int get() //获取当前的值
public final int getAndSet(int newValue)//获取当前的值，并设置新的值
public final int getAndIncrement()//获取当前的值，并自增
public final int getAndDecrement() //获取当前的值，并自减
public final int getAndAdd(int delta) //获取当前的值，并加上预期的值
boolean compareAndSet(int expect, int update) //如果输入的数值等于预期值，则以原子方式将该值设置为输入值（update）
public final void lazySet(int newValue)//最终设置为newValue,使用 lazySet 设置之后可能导致其他线程在之后的一小段时间内还是可以读到旧的值。

public final class Unsafe
{
private static final Unsafe theUnsafe;
public static final int INVALID_FIELD_OFFSET = -1;
private static native void registerNatives();
// 构造函数是private的，不允许外部实例化
private Unsafe(){
}
@CallerSensitive
public static Unsafe getUnsafe(){
Class var0 = Reflection.getCallerClass();
// 仅在引导类加载器`BootstrapClassLoader`加载时才合法
if(!VM.isSystemDomainLoader(var0.getClassLoader())){
throw new SecurityException("Unsafe");
}
else{
return theUnsafe;
}
}
}

public Unsafe getUnsafe() throws IllegalAccessException {
try{
Field unsafeField = Unsafe.class.getDeclaredField("theUnsafe");
unsafeField.setAccessible(true);
Unsafe unsafe = (Unsafe) unsafeField.get(null);
return unsafe;
}
catch (Exception e){
log.error(e.getMessage(), e);
return null;
}
}