http://www.w3cfuns.com/thread-297-1-1.html
http://www.jb51.net/article/26453.htm
http://wenku.baidu.com/link?url=Usfi_LRVUz9JxgcMqazT4yre8OJOCYD9dhFhHpSlPqEEAYyAEr_knIS6Na93CjBSd85-o0YH9RjacgIAteBNd2SSUQus_cNKNCORCRoEtb3
http://www.cnblogs.com/duanhuajian/archive/2012/09/23/2699119.html