AtomicReference原子更新方法详解

// 定义一个简单的状态类
class State {
    final String name;
    final int value;

    State(String name, int value) {
        this.name = name;
        this.value = value;
    }

    @Override
    public String toString() {
        return "State{" + "name='" + name + '\'' + ", value=" + value + '}';
    }
}

// 使用AtomicReference管理状态对象
AtomicReference stateRef = new AtomicReference<>(new State("INIT", 0));

// 原子获取当前值
State currentState = stateRef.get();

// 原子设置新值
stateRef.set(new State("RUNNING", 1));

// CAS方式更新：期望是INIT状态时才更新为STARTING
State expected = currentState;
State update = new State("STARTING", 2);
boolean success = stateRef.compareAndSet(expected, update);
if (success) {
    System.out.println("更新成功");
} else {
    System.out.println("更新失败，引用已被其他线程修改");
}

for (;;) {
    State oldState = stateRef.get();
    State newState = modify(oldState); // 根据旧状态生成新状态

    if (stateRef.compareAndSet(oldState, newState)) {
        break; // 成功退出
    }
    // 失败则重试，读取最新值继续
}

// 将当前状态的value加1，并返回更新前的值
State prev = stateRef.getAndUpdate(current -> 
    new State(current.name, current.value + 1)
);

// 基于当前值计算并返回结果
int newValue = stateRef.accumulateAndGet(
    new State("ADD", 10),
    (current, update) -> new State(current.name, current.value + update.value)
).value;