http://wenku.baidu.com/link?url=DRepNWw6YSm_uq8N7lmR2ibus8XBYmVraB0xpsamULINUvEADlOUR166whst4KJ8HEoYg9bNdwx48mYf3Fi72VZqKO4ei1lS9arEVs9qamK可以看看这个，希望对你有所启发
