/**
* @Author : sk 
* @Description :
*
* Copyright (C) 2007-2008 Oblog    
* All rights reserved
*/
/* jQuery图片预加载插件。  Dev By CssRain.cn */
jQuery.fn.loadthumb = function(options) {
    options = $.extend({
        src: ""
    }, options);
    var _self = this;
    _self.hide();
    var img = new Image();
    $(img).load(function() {
        _self.attr("src", options.src);
        _self.fadeIn("slow");
    }).attr("src", options.src);  //.attr("src",options.src)要放在load后面，
    return _self;
}