问题
I have 2 variable in my action class, id1 and id2. Joined by a _, they're used as a map key.
I am not able to retrieve the map value using this code:
<s:property value="%{mymap[id1_id2]}" />
How should I retrieve the map value?
回答1:
The expression id1_id2 in OGNL will assume the presence of a variable named id1_id2, since it's a perfectly legal identifier.
If you want to concatenate strings, you'd need:
<s:property value="%{mymap[id1 + '_' + id2]}" />
I'd likely create a separate variable to use as the key:
<s:set var="mapKey" value="%{id1 + '_' + id2}" />
<s:property value="%{mymap[#mapKey]}" />
Or more likely, I'd do it somewhere besides the view layer.
来源：https://stackoverflow.com/questions/8242704/how-to-concatenate-2-action-class-variables-in-struts-2