Spring State Machine Error Handling not working

问题

I did all the setup for error handling

@PostConstruct
public void addStateMachineInterceptor() {
    stateMachine.getStateMachineAccessor().withRegion().addStateMachineInterceptor(interceptor);
    stateMachine.getStateMachineAccessor().doWithRegion(errorinterceptor);
}

created interceptor to handle error:

@Service
public class OrderStateMachineFunction<T> implements StateMachineFunction<StateMachineAccess<String, String>> {
    @Override
    public void apply(StateMachineAccess<String, String> stringStringStateMachineAccess) {
        stringStringStateMachineAccess.addStateMachineInterceptor(
                new StateMachineInterceptorAdapter<String, String>() {
                    @Override
                    public Exception stateMachineError(StateMachine<String, String> stateMachine,
                                                       Exception exception) {
                        // return null indicating handled error
                        return exception;
                    }
                });
    }
}

But I can't see the call going into OrderStateMachineFunction, when we throw the exception from the action.

And after that state machine behave some wired way, like it stops calling preStateChange method after this.stateMachine.sendEvent(eventData);. It seems state machine breaks down after you throw the exception from the action.

    @Service
    public class OrderStateMachineInterceptor extends StateMachineInterceptorAdapter {

        @Override
        public void preStateChange(State newState, Message message, Transition transition, StateMachine stateMachine) {
            System.out.println("Manish");
    }
}

After trying few bit, I have seen that if I comment the resetStateMachine, it works as expected, but without that I am not able to inform the currentstate to state machine:

    public boolean fireEvent(Object data, String previousState, String event) {
        Message<String> eventData = MessageBuilder.withPayload(event)
                .setHeader(DATA_KEY, data)
                .build();
        this.stateMachine.stop();

//        this.stateMachine
//                .getStateMachineAccessor()
//                .withRegion()
//                .resetStateMachine(new DefaultStateMachineContext(previousState, event, eventData.getHeaders(), null));

        this.stateMachine.start();
        return this.stateMachine.sendEvent(eventData);
    }

回答1:

Not sure if you still need this. But I bumped into similar issue. I wanted to propagate exception from state machine to the caller. I implemented StateMachineInterceptor. And inside the state machine transition functions I am setting:

   try
        {
            ..
        }
        catch (WhateverException e)
        {
            stateMachine.setStateMachineError(e);
            throw e;
        }

Then inside the interceptor's stateMachineError method, I have added the Exception in the extendedState map:

public Exception stateMachineError(StateMachine<States, Events> stateMachine, Exception exception)
{ 
stateMachine.getExtendedState().getVariables().put("ERROR", exception);
logger.error("StateMachineError", exception);
return exception;
}

Inside resetStateMachine I have added the interceptor to the statemachine.

a.addStateMachineInterceptor(new LoggingStateMachineInterceptor());

Then when I am calling the sendEvent method, I am doing this:

 if (stateMachine.hasStateMachineError())
        {
            throw (Exception) svtStateMachine.getExtendedState().getVariables().get("ERROR");
        }

This is returning the WhateverException right to the caller. Which in my case is a RestController.

来源：https://stackoverflow.com/questions/37856322/spring-state-machine-error-handling-not-working

标签

java

Spring

spring-boot

spring-statemachine