对字符串进行 URL编码解码，有些程序比如关于internet 客户端程序或者是 跟WEB页面交互的程序需要将字符串进行URL编码然后才能发送等，可以用此程序里的相关函数进行封装。-In a URL coding and decoding, some programs such as Internet client program or with WEB page is interactive program need to will character string coding and then you can send URL, etc, can use this program encapsulate relevant function.