>>105
1.1 の APIリファレンス読めよ。

> To convert a String, each character is examined in turn:
> * The ASCII characters 'a' through 'z', 'A' through 'Z', and '0' through '9' remain the same.
> * The space character ' ' is converted into a plus sign '+'.
> * All other characters are converted into the 3-character string "%xy",
>　 where xy is the two-digit hexadecimal representation of the lower 8-bits of the character.