AJAX（XMLHttpRequest）进行跨域请求方法详解

http://blog.csdn.net/net_lover/archive/2010/01/11/5172509.aspx

http://blog.csdn.net/net_lover/archive/2010/01/11/5172522.aspx

http://blog.csdn.net/net_lover/archive/2010/01/11/5172532.aspx

http://msdn.microsoft.com/zh-cn/library/cc288060(v=VS.85).aspx