實際的企業應用中狀态機的流程會更加複雜,而我們最常用到的就是choice。它類似于java的if語句,作為條件判斷的分支而存在,讓我們先看一張圖:
這張圖表現的是一個表單(form)的整個狀态流程:
- 建立初始的空白表單( BLANK_FORM)
- 填寫(WRITE)表單,成為填充完表單(FULL_FORM)
- 檢查(CHEKC)表單
- 如果是表單名(formName)不為null,表單成為待送出表單(CONFIRM_FROM)
- 送出(SUBMIT)表單,成為成功送出表單(SUCCESS_FORM)
- 檢查(CHECK)表單
- 如果表單名為null,表單成為待處理表單(DEAL_FORM),修改formName
- 處理(DEAL)表單
- 如果表單名還是null或者裡面有個“壞”字,表單狀态變成廢單(FAILED_FORM)
- 如果表單名稱沒問題,表單狀态變成填充完表單狀态(FULL_FORM),重新走流程
大家不要在意這個例子的幼稚,畢竟它還是能用簡單的方式展現出流程的複雜性(這話多麼的辯證統一)。它有判斷分支(還有兩個),還有流程的循環,還有分支判斷後的直接失敗和分支判斷後的後續環節,後面我們會在代碼中告訴大家這裡面需要注意的東西。
代碼實作
先上狀态機的四件套:States,Events,Builder和EventConfig(spring statemachine還是蠻簡單的,來來回回就這幾樣東西)
public enum ComplexFormStates {
BLANK_FORM, // 空白表單
FULL_FORM, // 填寫完表單
CHECK_CHOICE,//表單校驗判斷
DEAL_CHOICE,//表單處理校驗
DEAL_FORM,//待處理表單
CONFIRM_FORM, // 校驗完表單
SUCCESS_FORM,// 成功表單
FAILED_FORM//失敗表單
}
注意一點,choice判斷分支本身也是一種狀态,要聲明出來,這裡是CHECK_CHOICE和DEAL_CHOICE
public enum ComplexFormEvents {
WRITE, // 填寫
CHECK,//校驗
DEAL,//處理
SUBMIT // 送出
}
同樣的分支事件也要聲明,這裡是CHECK和DEAL。
大頭是MachineBuilder,這個代碼就比較多,大家最好對照着上面這張圖來看,會比較清晰
/**
* 複雜訂單狀态機建構器
*/
@Component
public class ComplexFormStateMachineBuilder {
private final static String MACHINEID = "complexFormMachine";
/**
* 建構狀态機
*
* @param beanFactory
* @return
* @throws Exception
*/
public StateMachine<ComplexFormStates, ComplexFormEvents> build(BeanFactory beanFactory) throws Exception {
StateMachineBuilder.Builder<ComplexFormStates, ComplexFormEvents> builder = StateMachineBuilder.builder();
System.out.println("建構複雜表單狀态機");
builder.configureConfiguration()
.withConfiguration()
.machineId(MACHINEID)
.beanFactory(beanFactory);
builder.configureStates()
.withStates()
.initial(ComplexFormStates.BLANK_FORM)
.choice(ComplexFormStates.CHECK_CHOICE)
.choice(ComplexFormStates.DEAL_CHOICE)
.states(EnumSet.allOf(ComplexFormStates.class));
builder.configureTransitions()
.withExternal()
.source(ComplexFormStates.BLANK_FORM).target(ComplexFormStates.FULL_FORM)
.event(ComplexFormEvents.WRITE)
.and()
.withExternal()
.source(ComplexFormStates.FULL_FORM).target(ComplexFormStates.CHECK_CHOICE)
.event(ComplexFormEvents.CHECK)
.and()
.withChoice()
.source(ComplexFormStates.CHECK_CHOICE)
.first(ComplexFormStates.CONFIRM_FORM, new ComplexFormCheckChoiceGuard())
.last(ComplexFormStates.DEAL_FORM)
.and()
.withExternal()
.source(ComplexFormStates.CONFIRM_FORM).target(ComplexFormStates.SUCCESS_FORM)
.event(ComplexFormEvents.SUBMIT)
.and()
.withExternal()
.source(ComplexFormStates.DEAL_FORM).target(ComplexFormStates.DEAL_CHOICE)
.event(ComplexFormEvents.DEAL)
.and()
.withChoice()
.source(ComplexFormStates.DEAL_CHOICE)
.first(ComplexFormStates.FULL_FORM, new ComplexFormDealChoiceGuard())
.last(ComplexFormStates.FAILED_FORM);
return builder.build();
}
}
- 在我們熟悉的withExternal之後,我們迎來了為choice專門準備的withChoice()和跟随它的first(),last()。這兩個代表的就是分支判斷時TRUE和FALSE的狀态流程去處,這裡面涉及到的一個問題就是,TRUE和FALSE的判斷條件是什麼呢,根據啥來判斷呢?
- Guard就承擔了這個判斷的功能,看名字似乎不像。它在spring statemachine本來是用來保護這個狀态跳轉過程的,是以用guard,但在choice裡面,它就是作為判斷代碼而存在的,代碼如下:
public class ComplexFormCheckChoiceGuard implements Guard<ComplexFormStates, ComplexFormEvents> {
@Override
public boolean evaluate(StateContext<ComplexFormStates, ComplexFormEvents> context) {
boolean returnValue = false;
Form form = context.getMessage().getHeaders().get("form", Form.class);
if (form.formName == null) {
returnValue = false;
} else {
returnValue = true;
}
return returnValue;
}
}
它隻implements一個方法evaluate(),傳回boolean類型,是以很适合做這個判斷的功能。另外一個DEAL_CHOICE的gurad代碼是這樣的
public class ComplexFormDealChoiceGuard implements Guard<ComplexFormStates, ComplexFormEvents> {
@Override
public boolean evaluate(StateContext<ComplexFormStates, ComplexFormEvents> context) {
System.out.println("ComplexFormDealChoiceGuard!!!!!!!!!!!!!");
boolean returnValue = false;
Form form = context.getMessage().getHeaders().get("form", Form.class);
if ((form.formName == null)||(form.formName.indexOf("壞") > -1)) {
returnValue = false;
} else {
returnValue = true;
}
System.out.println(form.toString()+" is "+returnValue);
return returnValue;
}
}
還有四件套的最後一個EventConfig:
@WithStateMachine(id="complexFormMachine")
public class ComplexFormEventConfig {
private Logger logger = LoggerFactory.getLogger(getClass());
/**
* 目前狀态BLANK_FORM
*/
@OnTransition(target = "BLANK_FORM")
public void create() {
logger.info("---空白複雜表單---");
}
@OnTransition(source = "BLANK_FORM", target = "FULL_FORM")
public void write(Message<ComplexFormEvents> message) {
System.out.println("傳遞的參數:" + message.getHeaders().get("form"));
logger.info("---填寫完複雜表單---");
}
@OnTransition(source = "FULL_FORM", target = "CHECK_CHOICE")
public void check(Message<ComplexFormEvents> message) {
System.out.println("傳遞的參數:" + message.getHeaders().get("form").toString());
logger.info("---校驗複雜表單---");
}
//不會執行
@OnTransition(source = "CHECK_CHOICE", target = "CONFIRM_FORM")
public void check2confirm(Message<ComplexFormEvents> message) {
System.out.println("傳遞的參數:" + message.getHeaders().get("form").toString());
logger.info("---校驗表單到待送出表單(choice true)---");
}
//不會執行
@OnTransition(source = "CHECK_CHOICE", target = "DEAL_FORM")
public void check2deal(Message<ComplexFormEvents> message) {
System.out.println("傳遞的參數:" + message.getHeaders().get("form").toString());
logger.info("---校驗表單到待送出表單(choice false)---");
}
@OnTransition(source = "DEAL_FORM", target = "DEAL_CHOICE")
public void deal(Message<ComplexFormEvents> message) {
System.out.println("傳遞的參數:" + message.getHeaders().get("form").toString());
logger.info("---處理複雜表單---");
}
//不會執行
@OnTransition(source = "DEAL_CHOICE", target = "FAILED_FORM")
public void deal2fail(Message<ComplexFormEvents> message) {
System.out.println("傳遞的參數:" + message.getHeaders().get("form").toString());
logger.info("---處理複雜表單失敗(choice false)---");
}
//不會執行
@OnTransition(source = "DEAL_CHOICE", target = "FULL_FORM")
public void deal2full(Message<ComplexFormEvents> message) {
System.out.println("傳遞的參數:" + message.getHeaders().get("form").toString());
logger.info("---處理複雜表單到重新填寫表單(choice true)---");
}
/**
* CONFIRM_FORM->SUCCESS_FORM 執行的動作
*/
@OnTransition(source = "CONFIRM_FORM", target = "SUCCESS_FORM")
public void submit(Message<ComplexFormEvents> message) {
System.out.println("傳遞的參數:" + message.getHeaders().get("form").toString());
logger.info("---表單送出成功---");
}
}
這邊的代碼沒有任何特别的地方,唯一需要需要注意的是我标注的不會執行的這幾個方法。因為在choice判斷的時候,從一個狀态轉變到另外一個狀态時,是不會在eventConfig觸發方法的,比如這個方法:
//不會執行
@OnTransition(source = "CHECK_CHOICE", target = "CONFIRM_FORM")
public void check2confirm(Message<ComplexFormEvents> message) {
System.out.println("傳遞的參數:" + message.getHeaders().get("form").toString());
logger.info("---校驗表單到待送出表單(choice true)---");
}
我定義了如果使用者從CHECK_CHOICE狀态如果判斷後變成CONFIRM_FORM,執行check2confirm方法,但可惜,狀态的确變化了,但這個方法不會執行,隻有在做判斷的時候會執行ComplexFormCheckChoiceGuard的evaluate()。這就有個問題,在實際運作中,我們的确會需要在choice做出判斷狀态改變的時候要做些業務處理,比如表單check成功後需要通知後續人員來處理什麼的,這該怎麼辦呢?
- 簡單除暴第一招,直接在gurad裡面處理。這種方法其實沒有任何問題,因為既然判斷的業務代碼在這裡面,我們把判斷完成後需要做的事也在這裡寫完不就行了。但是,本着無關的業務能解耦就解耦的原則,我們還有一個辦法
- 漂亮解耦第二招,寫個action。下面介紹下這個action。
action,看這個名字就知道是要搞事情的,之前我們把業務代碼都是寫到eventConfig的方法裡面,但其實可以不怎麼幹,我們完全可以在每個狀态變化的時候獨立寫一個action,這樣的話就能做到業務的互不打擾。不如下面這段:
.withChoice()
.source(ComplexFormStates.CHECK_CHOICE)
.first(ComplexFormStates.CONFIRM_FORM, new ComplexFormCheckChoiceGuard(),new ComplexFormChoiceAction())
.last(ComplexFormStates.DEAL_FORM,new ComplexFormChoiceAction())
.and()
這是builder裡面的代碼片段,我們直接把action插入進來,在狀态變化的時候就能在action裡面處理了,下面是這個action的代碼:
public class ComplexFormChoiceAction implements Action<ComplexFormStates, ComplexFormEvents> {
@Override
public void execute(StateContext<ComplexFormStates, ComplexFormEvents> context) {
System.out.println("into ComplexFormChoiceAction");
Form form = context.getMessage().getHeaders().get("form", Form.class);
System.out.println(form);
System.out.println(context.getStateMachine().getState());
}
}
這裡面隻有一個execute的方法,簡單明了,我們需要的參數通過context傳遞,其實還是message,這樣的話,不同業務用不同的action就行了,我們再回頭看builder裡面插入action的地方:
action可以多個插入,也就是有多少單獨的業務需要在這裡面處理都行,其實回過頭來,不止在withChoice()裡面可以,之前的withExternal()也是可以的,看代碼:
.withExternal()
.source(ComplexFormStates.FULL_FORM).target(ComplexFormStates.CHECK_CHOICE)
.event(ComplexFormEvents.CHECK)
.action(new ComplexFormChoiceAction(),new ComplexFormChoiceAction())
.guard(new ComplexFormCheckChoiceGuard())
.and()
action可以插入多個,但guard在這裡恢複了本來的作用,保護狀态變化,是以隻能插入一個。
在controller裡面看結果
最後,我們還是需要看下運作的結果,我準備了三個流程:
- check成功,成為SUCCESS_FORM
- check失敗,deal成功,回到FULL_FORM
- check失敗,deal失敗,成為FAILED_FORM
對應的是form1,form2和form3,看代碼:
@Autowired
private ComplexFormStateMachineBuilder complexFormStateMachineBuilder;
......
@RequestMapping("/testComplexFormState")
public void testComplexFormState() throws Exception {
StateMachine<ComplexFormStates, ComplexFormEvents> stateMachine = complexFormStateMachineBuilder.build(beanFactory);
System.out.println(stateMachine.getId());
Form form1 = new Form();
form1.setId("111");
form1.setFormName(null);
Form form2 = new Form();
form2.setId("222");
form2.setFormName("好的表單");
Form form3 = new Form();
form3.setId("333");
form3.setFormName(null);
// 建立流程
System.out.println("-------------------form1------------------");
stateMachine.start();
Message message = MessageBuilder.withPayload(ComplexFormEvents.WRITE).setHeader("form", form1).build();
stateMachine.sendEvent(message);
System.out.println("目前狀态:" + stateMachine.getState().getId());
message = MessageBuilder.withPayload(ComplexFormEvents.CHECK).setHeader("form", form1).build();
stateMachine.sendEvent(message);
System.out.println("目前狀态:" + stateMachine.getState().getId());
message = MessageBuilder.withPayload(ComplexFormEvents.DEAL).setHeader("form", form1).build();
stateMachine.sendEvent(message);
System.out.println("目前狀态:" + stateMachine.getState().getId());
message = MessageBuilder.withPayload(ComplexFormEvents.SUBMIT).setHeader("form", form1).build();
stateMachine.sendEvent(message);
System.out.println("最終狀态:" + stateMachine.getState().getId());
System.out.println("-------------------form2------------------");
stateMachine = complexFormStateMachineBuilder.build(beanFactory);
stateMachine.start();
message = MessageBuilder.withPayload(ComplexFormEvents.WRITE).setHeader("form", form2).build();
stateMachine.sendEvent(message);
System.out.println("目前狀态:" + stateMachine.getState().getId());
message = MessageBuilder.withPayload(ComplexFormEvents.CHECK).setHeader("form", form2).build();
stateMachine.sendEvent(message);
System.out.println("目前狀态:" + stateMachine.getState().getId());
message = MessageBuilder.withPayload(ComplexFormEvents.DEAL).setHeader("form", form2).build();
stateMachine.sendEvent(message);
System.out.println("目前狀态:" + stateMachine.getState().getId());
message = MessageBuilder.withPayload(ComplexFormEvents.SUBMIT).setHeader("form", form2).build();
stateMachine.sendEvent(message);
System.out.println("最終狀态:" + stateMachine.getState().getId());
System.out.println("-------------------form3------------------");
stateMachine = complexFormStateMachineBuilder.build(beanFactory);
stateMachine.start();
message = MessageBuilder.withPayload(ComplexFormEvents.WRITE).setHeader("form", form3).build();
stateMachine.sendEvent(message);
System.out.println("目前狀态:" + stateMachine.getState().getId());
message = MessageBuilder.withPayload(ComplexFormEvents.CHECK).setHeader("form", form3).build();
stateMachine.sendEvent(message);
System.out.println("目前狀态:" + stateMachine.getState().getId());
form3.setFormName("好的表單");
message = MessageBuilder.withPayload(ComplexFormEvents.DEAL).setHeader("form", form3).build();
stateMachine.sendEvent(message);
System.out.println("目前狀态:" + stateMachine.getState().getId());
message = MessageBuilder.withPayload(ComplexFormEvents.SUBMIT).setHeader("form", form3).build();
stateMachine.sendEvent(message);
message = MessageBuilder.withPayload(ComplexFormEvents.CHECK).setHeader("form", form3).build();
stateMachine.sendEvent(message);
System.out.println("目前狀态:" + stateMachine.getState().getId());
message = MessageBuilder.withPayload(ComplexFormEvents.SUBMIT).setHeader("form", form3).build();
stateMachine.sendEvent(message);
System.out.println("最終狀态:" + stateMachine.getState().getId());
}
......