问题
How to prevent exception,
if requestParameters.sortBy is passed as string (java.lang.NumberFormatException) or is missing (java.lang.NullPointerException)?
<view-state id="journeySearch" model="journeyForm">
...
<transition on="sort">
<set name="journeyCriteria.sortBy" value="requestParameters.sortBy" type="int" />
<evaluate expression="bookingService.searchJourneys(journeyCriteria)" result="viewScope.journeys" />
</transition>
</view-state>
回答1:
requestParameters.sortBy will be null if it doesn't exist, but it should not throw a NullPointerException
about the NumberFormatException, you could use something like that:
<global-transitions>
<transition on-exception="java.lang.NumberFormatException" to=""/>
</global-transitions>
you could also implement your own exception-handler and use it with <exception-handler bean=""/> you can use it at the flow or state level.
来源：https://stackoverflow.com/questions/13086376/spring-web-flow-exception-handling