Thanks to your guides, my problem  was not any of them
you considered, My MySqlServer setup and ini file was
correct and also, I have not any problem in my editor,
jsp or in Struts code.
The problem was in Tomcat server:(
In administration page (/admin) there is a "Connector
(8080)" node under
-"Tomcat Server"
----"Service (Catalina)"
--------"Connector (8080)"
which has following two properties:
URI Encoding:
Use Body Encoding For URI Query
Parameters:(true/false)
I set the values to "utf-8" and "true" and NOW...
Everything is going well.