以一个简单的二级审批流程（请假）为例，研究一下 StateMachine 的使用。该流程设计如下：
目标：通过 StateMachine 实现该二级审批流程，提供 API 给第三方调用。
将流程图上的 5 个状态（不包括开始和结束）定义如下：
public enum States {
WAITING_FOR_SUBMIT, // 等待提交
WAITING_FOR_TL_APPROVE, // 等待 TL 审批
WAITING_FOR_DM_APPROVE, // 等待 DM 审批
WAITING_FOR_HR_RECORD, // 等待 HR 备案
END, // 流程结束
}
将流程图上的 6 个事件（不括开始和结束）定义如下：
public enum Events {
SUBMIT, // 提交申请
TL_AGREE, // WAITING_FOR_TL_APPROVE 审批
TL_REJECT, // WAITING_FOR_TL_APPROVE 驳回
DM_AGREE, // 部门经理审批
DM_REJECT, // 部门经理驳回
HR_RECORD, // WAITING_FOR_HR_RECORD 备案
}
主要是配置状态、事件和迁移。
@Configuration
@EnableStateMachine
public class StateMachineConfig extends EnumStateMachineConfigurerAdapter<States, Events> {
@Autowired
private LeaveStateMachinePersist leaveStateMachinePersist;
@Bean
public StateMachinePersister<States,Events,String> stateMachinePersist(){
return new DefaultStateMachinePersister<>(leaveStateMachinePersist);
}
@Override
public void configure(StateMachineStateConfigurer<States, Events> states)
throws Exception {
states
.withStates()
.initial(States.WAITING_FOR_SUBMIT)
.states(EnumSet.allOf(States.class));
}
@Override
public void configure(StateMachineTransitionConfigurer<States, Events> transitions)
throws Exception {
transitions
.withExternal()
.source(States.WAITING_FOR_SUBMIT).target(States.WAITING_FOR_TL_APPROVE)
.event(Events.SUBMIT)
.and()
.withExternal()
.source(States.WAITING_FOR_TL_APPROVE).target(States.WAITING_FOR_DM_APPROVE)
.event(Events.TL_AGREE)
.and()
.withExternal()
.source(States.WAITING_FOR_TL_APPROVE).target(States.WAITING_FOR_SUBMIT)
.event(Events.TL_REJECT)
.and()
.withExternal()
.source(States.WAITING_FOR_DM_APPROVE).target(States.WAITING_FOR_HR_RECORD)
.event(Events.DM_AGREE)
.and()
.withExternal()
.source(States.WAITING_FOR_DM_APPROVE).target(States.WAITING_FOR_SUBMIT)
.event(Events.DM_REJECT)
.and()
.withExternal()
.source(States.WAITING_FOR_HR_RECORD).target(States.END)
.event(Events.HR_RECORD);
}
其中 LeaveStateMachinePersist 是自定义的持久化对象，用于恢复状态机的状态，因为不同的业务对象共用同一个状态机，状态机的状态根据业务 id 来缓存。LeaveStateMachinePersist 目前很简单，仅仅是一个 HashMap 来保存业务 id 和对于的 StateMachineContext：
@Component
public class LeaveStateMachinePersist implements StateMachinePersist<States,Events,String> {
// 用 map 来模拟持久化存储，可替换成数据库
static Map<String, States> cache = new HashMap<>(16);
@Override
public void write(StateMachineContext<States, Events> stateMachineContext, String s) {
cache.put(s, stateMachineContext.getState());
}
@Override
public StateMachineContext<States, Events> read(String s) {
return cache.containsKey(s) ?
new DefaultStateMachineContext<>(cache.get(s),null,null,null,null,"请假流程") :
new DefaultStateMachineContext<>(States.WAITING_FOR_SUBMIT,null,null,null,null,"请假流程");
}
}
控制器负责对外提供 RESTFul 接口。有 6 个 RequestMapping，分别执行新建请假条、提交、tl审批、dm审批、hr备案和获取状态机当前状态 6 个操作。
@RestController
public class StateMachineController {
@Autowired
private StateMachinePersister<States, Events, String> persister;
@Autowired
private StateMachine<States, Events> stateMachine;
@RequestMapping("/new")
@ResponseBody
public BaseResponse newLeave(@RequestBody LeaveRequest leave){
BaseResponse result = new BaseResponse();
stateMachine.start();
result.message = "新建请假申请成功";
result.success = true;
result.data = leave;
return result;
}
@RequestMapping("/apply")
@ResponseBody
public BaseResponse apply(@RequestBody JSONObject params){
String leaveId = params.getAsString("leaveId");
return sendEvent(Events.SUBMIT,leaveId);
}
@RequestMapping("/tlApprove")
@ResponseBody
public BaseResponse tlApprove(@RequestBody JSONObject params) {
String id = params.getAsString("leaveId");
boolean agree = params.getAsNumber("agree").intValue() != 0;
return sendEvent(agree ? Events.TL_AGREE : Events.TL_REJECT, id);
}
@RequestMapping("/dmApprove")
@ResponseBody
public BaseResponse dmApprove(@RequestBody JSONObject params) {
String id = params.getAsString("leaveId");
boolean agree = params.getAsNumber("agree").intValue() != 0;
return sendEvent(agree ? Events.DM_AGREE : Events.DM_REJECT, id);
}
@RequestMapping("/hrRecord")
@ResponseBody
public BaseResponse hrRecord(@RequestBody JSONObject params) {
String id = params.getAsString("leaveId");
return sendEvent(Events.HR_RECORD,id);
}
@RequestMapping("/getState")
@ResponseBody
public BaseResponse getState(@RequestBody JSONObject params){
String leaveId = params.getAsString("leaveId");
BaseResponse result = new BaseResponse();
try{
persister.restore(stateMachine,leaveId);
result.success = true;
States state = stateMachine.getState().getId();
result.data = state;
}catch (Exception e){
e.printStackTrace();
}finally {
stateMachine.stop();
return result;
}
}
private BaseResponse sendEvent(Events event,String leaveId){
BaseResponse result = new BaseResponse();
if(leaveId == null || leaveId.length()==0){
result.success = false;
result.message = "leaveId 不能为空";
return result;
}
try {
// 根据业务 id 获取状态
persister.restore(stateMachine,leaveId);
result.success = stateMachine.sendEvent(event);
// 持久化状态机
if (result.success) {
persister.persist(stateMachine, leaveId);
}
JSONObject data = new JSONObject();
result.message = result.success ? "执行成功":"执行失败";
result.message = result.message + "，当前状态为："+stateMachine.getState().getId();
data.put("leaveId",leaveId);
data.put("event",event.toString());
data.put("state",stateMachine.getState().getId());
result.data = data;
} catch (Exception e) {
e.printStackTrace();
result.message = e.getMessage();
}finally {
stateMachine.stop();
return result;
}
}
}
注意 leaveId 是业务 id，代表了一个业务对象（比如请假条 LeaveRequest）。leaveId 是一个 UUID，保证不会重复。
运行程序，会自动在 8080 端口上运行 tomcat。然后就可以用 postman 调用各个接口进行测试了：