Extjs如何动态加载图片。帮帮忙啊

Extjs如何动态加载图片。帮帮忙啊 --------------------编程问答-------------------- 这你得看说明 --------------------编程问答-------------------- 参考：http://blog.csdn.net/tk1905345/article/details/7899928 --------------------编程问答-------------------- 用 Ext.Img  --------------------编程问答--------------------  xtype: 'box',
                 id: 'browseImage',
                 fieldLabel: "预览图片",
                 autoEl: {
                     width: 30,
                     height: 50,
                     tag: 'img',
                     type: 'image',
                     src: pic,
                     style: 'filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale);',
                     complete: 'off',
                     id: 'imageBrowse'
                 }
                , listeners: {
                    'render': function (_field) {
                        _field.getEl().dom.src = pic;
                    }
                }

这个src路径如何动态获取

补充：.NET技术 ,  ASP.NET