/**
* AtomicInteger 原子Integer操作类 继承Number抽象类
*/
public class AtomicInteger extends Number implements java.io.Serializable {
private static final long serialVersionUID = 6214790243416807050L;
/**
* 引入Unsafe类 并获取value在对象重的内存地址偏移量
*/
private static final Unsafe unsafe = Unsafe.getUnsafe();
private static final long valueOffset;
static {
try {
valueOffset = unsafe.objectFieldOffset(AtomicInteger.class.getDeclaredField("value"));
} catch (Exception ex) { throw new Error(ex); }
}
/** 定义int的value */
private volatile int value;
/** 构造方法 */
public AtomicInteger(int initialValue) {
value = initialValue;
}
public AtomicInteger() {
}
public final int get() {
return value;
}
public final void set(int newValue) {
value = newValue;
}
/**
* 利用unsafe类操作实现原子操作
*/
public final void lazySet(int newValue) {
unsafe.putOrderedInt(this, valueOffset, newValue);
}
public final int getAndSet(int newValue) {
return unsafe.getAndSetInt(this, valueOffset, newValue);
}
/**
* 比较并赋值
*/
public final boolean compareAndSet(int expect, int update) {
return unsafe.compareAndSwapInt(this, valueOffset, expect, update);
}
public final boolean weakCompareAndSet(int expect, int update) {
return unsafe.compareAndSwapInt(this, valueOffset, expect, update);
}
/**
* +1与-1的原子操作 返回操作前的值
*/
public final int getAndIncrement() {
return unsafe.getAndAddInt(this, valueOffset, 1); //操作直到完成
}
public final int getAndDecrement() {
return unsafe.getAndAddInt(this, valueOffset, -1); //操作直到完成
}
/**
* 添加指定值 并返添加前的值
*/
public final int getAndAdd(int delta) {
return unsafe.getAndAddInt(this, valueOffset, delta); //操作直到完成
}
/**
* 同上操作 返回操作后的值
*/
public final int incrementAndGet() {
return unsafe.getAndAddInt(this, valueOffset, 1) + 1; //操作直到完成
}
public final int decrementAndGet() {
return unsafe.getAndAddInt(this, valueOffset, -1) - 1; //操作直到完成
}
public final int addAndGet(int delta) {
return unsafe.getAndAddInt(this, valueOffset, delta) + delta;
}
/** 根据传入的函数式接口对值进行操作 */
public final int getAndUpdate(IntUnaryOperator updateFunction) {
int prev, next;
do {
prev = get();
next = updateFunction.applyAsInt(prev);
} while (!compareAndSet(prev, next)); //循环操作直到操作成功
return prev;
}
public final int updateAndGet(IntUnaryOperator updateFunction) {
int prev, next;
do {
prev = get();
next = updateFunction.applyAsInt(prev);
} while (!compareAndSet(prev, next));//循环操作直到操作成功
return next;
}
public final int getAndAccumulate(int x, IntBinaryOperator accumulatorFunction) {
int prev, next;
do {
prev = get();
next = accumulatorFunction.applyAsInt(prev, x);
} while (!compareAndSet(prev, next));//循环操作直到操作成功
return prev;
}
public final int accumulateAndGet(int x, IntBinaryOperator accumulatorFunction) {
int prev, next;
do {
prev = get();
next = accumulatorFunction.applyAsInt(prev, x);
} while (!compareAndSet(prev, next));//循环操作直到操作成功
return next;
}
public String toString() {
return Integer.toString(get());
}
public int intValue() {
return get();
}
public long longValue() {
return (long)get();
}
public float floatValue() {
return (float)get();
}
public double doubleValue() {
return (double)get();
}
}
Java多线程深入学习-atomic原子类实现-AtomicInteger源码分析
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转载自blog.csdn.net/luo_mu_hpu/article/details/106687883
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