web技术之图片预加载
http://www.cnblogs.com/rt0d/archive/2011/04/17/2018646.html
http://www.oschina.net/code/snippet_54371_8015
出处:http://cnblogs.com/daishuguang
http://www.cnblogs.com/rt0d/archive/2011/04/17/2018646.html
http://www.oschina.net/code/snippet_54371_8015