当文件上传器文本框为空后单击按钮时，如何说明文件上传器的维护，此问题是在发布应用程序后创建的 [英] how can state maintain of file uploader when we click a button after that file uploader text box is empty this problem is create after publish application

问题描述

当文件上传器文本框为空后单击按钮时，如何说明文件上传器的维护，此问题在发布applicationplz help后创建.

how can state maintain of file uploader when we click a button after that file uploader text box is empty this problem is create after publish applicationplz help

推荐答案

底线-使用标准的文件上传控件，您无法保持状态.它是HTML中的一种特殊类型的控件，它在特殊的沙箱中运行，因此您也无法使用JavaScript对其进行操作.出现这种情况的原因是，浏览器被严格地沙盒化，因此它不允许您确定目录结构是什么.

还有其他文件上传组件，但是它们倾向于使用Flash之类的东西-也许其中之一可能更符合您的需求.

Bottom line - with the standard file upload control, you can''t maintain state. It''s a special type of control in HTML, and it runs inside a special sandbox so that you can''t manipulate it with JavaScript either. The reason that this is the case is that the browser is tightly sandboxed so that it doesn''t allow you to work out what the directory structure is.

There are alternative file upload components, but these tend to use things like Flash - perhaps one of these might be more what you require.

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