I have a problem with www class in android

hi there .
I have a problem with www class in android .
when i send a persian string to php file with Get method in pc , every characters in string is ok.

but when I send any persian character from android device , every character in string change to ‘?’ character.
is there any body to solve this problem ?

help me pleass

Do you have this in your xml file???

<?xml version="1.0" encoding="utf-8" ?>