The difference between '#', '%' and '$'

Question

I am new to struts2 and confused by the elements '#', '%' and '$'. There are several ways to use it:

${user.name}
%{user.name}
<s:radio list="#{key1:value1,key2:value2}" />

Can someone give me an explanation and examples?

Answer 1

Simply put

If $ {user.name} in the jsp page, this is an EL expression. If $ {user.name} is in struts.xml, this is an OGNL expression.

If% {user.name} on the jsp page, this is an OGNL expression.

Final, # {key1: value1, key2: value2} is an OGNL expression, it means creating a map that maps key1 to value1 and key2 to value2.

BTW: # {key1: value1, key2: value2} % {}, % {# {key1: value1, key2: value2}}, struts2 , OGNL , % {} .