Spring基于狀態機squirrel-foundation簡單使用

squirrel-foundation的一些使用方法在百度上資料還是比較少，我是根據以下三個大佬寫的文章借鑒的，在這里記錄一下。
1、squirrel-foundation-demo
2、Squirrel使用（中文文檔）
3、squirrel-foundation狀態機的使用細節
我在這里直接粘貼代碼，便于自己之后理解。

/**
* 通過Spring創建StateMachineBuilder實例，通過buidler創建狀態機(單例)
* 創建無類型化狀態機，簡化狀態機，防止過多泛化導致代碼不易閱讀(因為不太理解一些高級的使用)
*/
public abstract class AbstractStateMachineEngine <T extends UntypedStateMachine> implements ApplicationContextAware {
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private ApplicationContext applicationContext;
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protected UntypedStateMachineBuilder stateMachineBuilder = null;
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@SuppressWarnings("unchecked")
public AbstractStateMachineEngine() {
//識別泛型參數
Class<T> genericType = (Class<T>) GenericTypeResolver.resolveTypeArgument(getClass(),
AbstractStateMachineEngine.class);
stateMachineBuilder = StateMachineBuilderFactory.create(genericType, ApplicationContext.class);
}
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//注入applicationContext，并在創建StateMachine實例時注入
@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.applicationContext = applicationContext;
}
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/**
* 可以通過向OrderContext 上下文傳遞一些業務參數，比如orderId等等
*/
public boolean fire(EOrderEvents event, OrderContext context) {
T stateMachine = stateMachineBuilder.newUntypedStateMachine(
context.geteOrder().getOrderStatus(),
applicationContext);
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//由于StateMachine實例不是由Spring容器創建，所以這個過程中無法通過注解方式開啟事務(Spring沒有機會去創建事務代理)，因此采用了編程式事務
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);
//這里會返回狀態機是否出錯，如果出錯可用于通知Controller層，目前只會這樣簡單的操作
return stateMachine.isError();
} catch (Exception ex) {
//用于事務回滾
transactionManager.rollback(status);
return true;
}
}
}

/**
* 該類相當于監聽狀態變化，構造一些監聽方法實現一些邏輯代碼
* @States 定義狀態列表，里面可以包含多個狀態
* @State定義每個狀態，name狀態名稱，entryStateInit進入狀態時調用的方法，exitCallMethod 離開狀態是調用的方法，initialState 為true時，為默認狀態。
* */
@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")
})
//該地方向AbstractStateMachine傳遞的參數
@StateMachineParameters(stateType = OrderStates.class, eventType = OrderEvents.class, contextType = OrderContext.class)
public class SubmitOrderStateMachine extends AbstractStateMachine<UntypedStateMachine, Object, Object, Object> implements UntypedStateMachine {
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private OrderService OrderService;
protected ApplicationContext applicationContext;
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//定義構造函數接受ApplicationContext注入([參看New State Machine Instance](http://hekailiang.github.io/squirrel/))
public SubmitOrderStateMachine(ApplicationContext applicationContext) {
this.applicationContext = applicationContext;
// 通過applicationContext注入orderService，這樣就可以通過service操作數據庫
OrderService = (OrderService) this.applicationContext.getBean("OrderService");
}
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//創建訂單，依舊處于待使用狀態
public void createOrder(OrderStates fromState, OrderStates toState, OrderEvents OrderEvents, OrderContext OrderContext) {
//可以做一些創建訂單等等操作
}
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//提交訂單
public void submitOrder(OrderStates fromState, OrderStates toState, OrderEvents OrderEvents, OrderContext OrderContext) {
}
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//支付訂單
public void pay(OrderStates fromState, OrderStates toState, OrderEvents OrderEvents, OrderContext OrderContext) {
}
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public void usingRefund(OrderStates fromState, OrderStates toState, OrderEvents OrderEvents, OrderContext OrderContext) {
}
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public void comRefund(OrderStates fromState, OrderStates toState, OrderEvents OrderEvents, OrderContext OrderContext) {
}
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/**
* 如果實現這個方法，當上面方法執行出現錯誤時就會轉到這里來執行。
* 但是由于自己是菜鳥，并不知道出錯后這里該如何通知到Controller層
* 因此這里并未實現，具體的實現方法請參考官網
*/
/*
@Override
protected void afterTransitionCausedException(Object fromState, Object toState, Object event, Object context) {
//super.afterTransitionCausedException(fromState, toState, event, context);
}*/
}

還需要一個類集成AbstractStateMachineEngine，用于調用fire()方法。該類需要添加@Service注解，以便spring注入

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

Controller層使用：

/**
* 這里需要加上try**catch**，以便發生錯誤可方便執行下去
*/
@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));
//向訂單上下文可添加一些邏輯參數，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("更新失敗，請重新嘗試!");
}
return resultEntity;
} catch (Exception e) {
e.printStackTrace();
log.error(e);
resultEntity.setCode(0);
resultEntity.setMessage("更新失敗，請重新嘗試!");
return resultEntity;
}
}