[問題]as2的escape,unescape

code:
System.useCodepage=true;
oldStr="ecardImg/%A6w%A5%FE%AEy%B4%C8%2Ejpg";
trace("oldStr : "+oldStr);
newStr=unescape(oldStr);
trace("newStr : "+newStr);
oldStr=escape(newStr);
trace("oldStr : "+oldStr);

output:
oldStr : ecardImg/%A6w%A5%FE%AEy%B4%C8%2Ejpg
newStr : ecardImg/安全座椅.jpg
oldStr : ecardImg%2F%A6w%A5%FE%AEy%B4%C8%2Ejpg

吃進去跟吐出來的不一樣！？