Spring基于状态机squirrel-foundation简单使用

squirrel-foundation的一些使用方法在百度上资料还是比较少，我是根据以下三个大佬写的文章借鉴的，在这里记录一下。
1、squirrel-foundation-demo
2、Squirrel使用（中文文档）
3、squirrel-foundation状态机的使用细节
我在这里直接粘贴代码，便于自己之后理解。

/**
* 通过Spring创建StateMachineBuilder实例，通过buidler创建状态机(单例)
* 创建无类型化状态机，简化状态机，防止过多泛化导致代码不易阅读(因为不太理解一些高级的使用)
*/
public abstract class AbstractStateMachineEngine <T extends UntypedStateMachine> implements ApplicationContextAware {
private ApplicationContext applicationContext;
protected UntypedStateMachineBuilder stateMachineBuilder = null;
@SuppressWarnings("unchecked")
public AbstractStateMachineEngine() {
//识别泛型参数
Class<T> genericType = (Class<T>) GenericTypeResolver.resolveTypeArgument(getClass(),
AbstractStateMachineEngine.class);
stateMachineBuilder = StateMachineBuilderFactory.create(genericType, ApplicationContext.class);
}
//注入applicationContext，并在创建StateMachine实例时注入
@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.applicationContext = applicationContext;
}
/**
* 可以通过向OrderContext 上下文传递一些业务参数，比如orderId等等
*/
public boolean fire(EOrderEvents event, OrderContext context) {
T stateMachine = stateMachineBuilder.newUntypedStateMachine(
context.geteOrder().getOrderStatus(),
applicationContext);
//由于StateMachine实例不是由Spring容器创建，所以这个过程中无法通过注解方式开启事务(Spring没有机会去创建事务代理)，因此采用了编程式事务
DataSourceTransactionManager transactionManager = (DataSourceTransactionManager)applicationContext.getBean("transactionManager");
DefaultTransactionDefinition def = new DefaultTransactionDefinition();
def.setPropagationBehavior(TransactionDefinition.PROPAGATION_REQUIRED);
TransactionStatus status = transactionManager.getTransaction(def);
try {
stateMachine.fire(event, context);
transactionManager.commit(status);
//这里会返回状态机是否出错，如果出错可用于通知Controller层，目前只会这样简单的操作
return stateMachine.isError();
} catch (Exception ex) {
//用于事务回滚
transactionManager.rollback(status);
return true;
}
}
}

/**
* 该类相当于监听状态变化，构造一些监听方法实现一些逻辑代码
* @States 定义状态列表，里面可以包含多个状态
* @State定义每个状态，name状态名称，entryStateInit进入状态时调用的方法，exitCallMethod 离开状态是调用的方法，initialState 为true时，为默认状态。
* */
@States({
@State(name = "UNFOUND", entryCallMethod = "entryStateInit", exitCallMethod = "exitStateInit", initialState = true),
@State(name = "USING", entryCallMethod = "entryStateWaitPay", exitCallMethod = "exitStateWaitPay"),
@State(name = "COMPLETE", entryCallMethod = "entryStateWaitSend", exitCallMethod = "exitStateWaitSend"),
@State(name = "REFUND", entryCallMethod = "entryStatePartSend", exitCallMethod = "exitStatePartSend"),
@State(name = "NOUSE", entryCallMethod = "entryStatePartSend", exitCallMethod = "exitStatePartSend")
})
@Transitions({
@Transit(from = "UNFOUND", to = "UNFOUND", on = "FOUND", callMethod = "createOrder"),
@Transit(from = "UNFOUND", to = "USING", on = "SAOMA", callMethod = "submitOrder"),
@Transit(from = "USING", to = "COMPLETE", on = "PAY", callMethod = "pay"),
@Transit(from = "USING", to = "REFUND", on = "USING_REFUNDING", callMethod = "usingRefund"),
@Transit(from = "COMPLETE", to = "REFUND", on = "COM_REFUNDING", callMethod = "comRefund")
})
//该地方向AbstractStateMachine传递的参数
@StateMachineParameters(stateType = OrderStates.class, eventType = OrderEvents.class, contextType = OrderContext.class)
public class SubmitOrderStateMachine extends AbstractStateMachine<UntypedStateMachine, Object, Object, Object> implements UntypedStateMachine {
private OrderService OrderService;
protected ApplicationContext applicationContext;
//定义构造函数接受ApplicationContext注入([参看New State Machine Instance](http://hekailiang.github.io/squirrel/))
public SubmitOrderStateMachine(ApplicationContext applicationContext) {
this.applicationContext = applicationContext;
// 通过applicationContext注入orderService，这样就可以通过service操作数据库
OrderService = (OrderService) this.applicationContext.getBean("OrderService");
}
//创建订单，依旧处于待使用状态
public void createOrder(OrderStates fromState, OrderStates toState, OrderEvents OrderEvents, OrderContext OrderContext) {
//可以做一些创建订单等等操作
}
//提交订单
public void submitOrder(OrderStates fromState, OrderStates toState, OrderEvents OrderEvents, OrderContext OrderContext) {
}
//支付订单
public void pay(OrderStates fromState, OrderStates toState, OrderEvents OrderEvents, OrderContext OrderContext) {
}
public void usingRefund(OrderStates fromState, OrderStates toState, OrderEvents OrderEvents, OrderContext OrderContext) {
}
public void comRefund(OrderStates fromState, OrderStates toState, OrderEvents OrderEvents, OrderContext OrderContext) {
}
/**
* 如果实现这个方法，当上面方法执行出现错误时就会转到这里来执行。
* 但是由于自己是菜鸟，并不知道出错后这里该如何通知到Controller层
* 因此这里并未实现，具体的实现方法请参考官网
*/
/*
@Override
protected void afterTransitionCausedException(Object fromState, Object toState, Object event, Object context) {
//super.afterTransitionCausedException(fromState, toState, event, context);
}*/
}

还需要一个类集成AbstractStateMachineEngine，用于调用fire()方法。该类需要添加@Service注解，以便spring注入

@Service
public class OrderStateMachineEngine extends AbstractStateMachineEngine<SubmitOrderStateMachine>{
}

Controller层使用：

/**
* 这里需要加上try**catch**，以便发生错误可方便执行下去
*/
@RequestMapping(value="/modOrderStatus",method = {RequestMethod.POST})
@ResponseBody
public ResultEntity<Order> modOrderStatus(@RequestParam("event") String event,int code,Long orderId){
ResultEntity<Order> resultEntity = new ResultEntity<Order>();
try {
Order Order = new Order();
Order.setOrderStatus(OrderStates.getState(code));
//向订单上下文可添加一些逻辑参数，如：orderId
OrderContext OrderContext = new OrderContext(Order, orderId);
if(!orderStateMachineEngine.fire(OrderEvents.getEvent(event), OrderContext)) {
resultEntity.setCode(1);
resultEntity.setMessage("成功!");
}else {
resultEntity.setCode(0);
resultEntity.setMessage("更新失败，请重新尝试!");
}
return resultEntity;
} catch (Exception e) {
e.printStackTrace();
log.error(e);
resultEntity.setCode(0);
resultEntity.setMessage("更新失败，请重新尝试!");
return resultEntity;
}
}