春季:/**和/*关于路径的差异 [英] Spring: Difference of /** and /* with regards to paths

问题描述

当我们引用路径时，两个星号而不是一个星号有什么区别?

What's the difference between two asterisks instead of one asterisk when we refer to paths?

之前，我正在调试Spring 3项目.我试图使用添加一个.swf

Earlier I was debugging my Spring 3 project. I was trying to add a .swf using

<spring:url var="flashy" value="/resources/images/flash.swf"/>

我的web.xml的ResourceServlet看起来像

With my web.xml's ResourceServlet looking like

<servlet-name>Resource Servlet </servlet-name>
<url-pattern>/resources/*</url-pattern>

但是不幸的是我遇到了这个错误:

But unfortunately I was getting this error:

WARN org.springframework.js.resources.ResourceServlet - An attempt to access a protected resource at /images/flash.swf was disallowed.

我发现这很奇怪，因为访问了images文件夹中的所有图像，但是.swf为何受到保护"?

I found it really strange since all my images in the images folder were accessed but how come my .swf was "protected"?

然后，我决定将/resources/*更改为/resources/**并最终成功.我的问题是...为什么?

Afterwards, I decided to change the /resources/* to /resources/** and it finally worked. My question is... why?

推荐答案

这是Apache ant中使用的路径模式，spring团队将其实现并在整个框架中使用它.

This is a path pattern that used in Apache ant, spring team implement it and use it throughout the framework.

有关参考，请参见 AntPathMatcher a>(最新的 javadoc似乎有问题，所以我链接了一个旧的.)

For reference, see javadoc of AntPathMatcher (newest javadoc seems to have problem, so I link an old one).

根据文档，回到您的问题，它只有3条规则:

Back to your problem, according to the document, it only have 3 rules:

1. ?匹配一个字符
2. *匹配零个或多个字符
3. **匹配路径中的零个或多个目录"

1. ? matches one character
2. * matches zero or more characters
3. ** matches zero or more 'directories' in a path

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