Printing log from flow.xml

问题

I am working on a web application with spring web flow. While I am working on a flow.xml file I have get a decision state on it like this -

<decision-state id="checkPermissin">    
    <if test="requestParameters.canApprove" then="approve" else="warning" />
</decision-state>  

When a request comes to the flow.xml then it get the request parameter canApprove from it and test whether it is true or false. Then it goes to the either of approve or warning state.

My question is - can I log/print the status of canApprove from the flow.xml file?

回答1:

You can add an on-exit tag to the end of the 'decision-state' and call any service methods, spring beans, or static methods on the classpath.

Try this (untested):

<decision-state id="checkPermissin">    
    <if test="requestParameters.canApprove" then="approve" else="warning" />
   <on-exit>
        <evaluate expression="T(org.apache.log4j.Logger).getLogger('someLogger').info(requestParameters.canApprove)"/>
   </on-exit>
</decision-state>

The above solution is more of a hack to fulfill what you are asking for. The "proper" way to log this is to extend a FlowExecutionListenerAdapter and to listen for your current flow + decision-state id "checkPermissin" then log whatever you desire about that flow but it would involve more setup/coding outside the flow.xml file. (see: Catch "dead" session in Spring webflow: the example is for catching exceptions but can easily be adapted for logging anything in a flow)

来源：https://stackoverflow.com/questions/30223805/printing-log-from-flow-xml