java Servlet 过滤器 url 映射
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Servlet filter url mapping
提问by J. Andrew Laughlin
How can a filter be mapped to the root of a URL? I'm using Tomcat 7.0.2 and deploying an application as ROOT.war. The welcome page is sign_in.xhtml. I would like to run a filter whenever the client sends a request for the root of the site (i.e. the domain name only), or when the the client requests sign_in.xhtml. Here is what I have so far:
如何将过滤器映射到 URL 的根？我正在使用 Tomcat 7.0.2 并将应用程序部署为 ROOT.war。欢迎页面是 sign_in.xhtml。我想在客户端发送对站点根目录的请求（即仅域名）或客户端请求 sign_in.xhtml 时运行过滤器。这是我到目前为止所拥有的：
<filter>
<filter-name>My filter</filter-name>
<filter-class>com.myApp.myFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>My filter</filter-name>
<url-pattern>/sign_in.xhtml</url-pattern>
</filter-mapping>
Requests for sign_in.xhtml directly, successfully invoke the filter, but I'm not sure how to get requests for the root to invoke the filter. According to the Servlet spec (version 3.0)
直接请求sign_in.xhtml，成功调用过滤器，但是我不知道如何获取root调用过滤器的请求。根据 Servlet 规范（3.0 版）
<url-pattern>/</url-pattern>
maps to the default servlet, and an empty string maps to the root. Here's the relevant section from the spec:
映射到默认 servlet，空字符串映射到根。这是规范中的相关部分：
"The empty string ("") is a special URL pattern that exactly maps to the application's context root, i.e., requests of the form http://host:port//. In this case the path info is '/' and the servlet path and context path is empty string (““)."
"空字符串 ("") 是一种特殊的 URL 模式，它精确地映射到应用程序的上下文根，即形式为http://host:port// 的请求。在这种情况下，路径信息是 '/' 并且servlet 路径和上下文路径为空字符串（“”）。”
However, both of the following url patterns cause Tomcat to throw an exception.
但是，以下两种 url 模式都会导致 Tomcat 抛出异常。
<url-pattern></url-pattern>
<url-pattern>""</url-pattern>
I would really appreciate it if someone could shed some light on this. Thank You.
如果有人能对此有所了解，我将不胜感激。谢谢。
Andrew
安德鲁
采纳答案by BalusC
The <url-pattern>/</url-pattern>should work for requests on the root. Did you try it?
本<url-pattern>/</url-pattern>应适用于根的请求。你试了吗？
If your intent is more to filter allrequests, then you should use <url-pattern>/*</url-pattern>.
如果您的意图更多地是过滤所有请求，那么您应该使用<url-pattern>/*</url-pattern>.
Update: To exclude one and other, I tested the url-patternof /at Tomcat 7 (using both web.xmland @WebFilter(urlPatterns={"/"})) and it indeed didn't work as expected. The url-patternof /however works as expected on Tomcat 6 (Servlet 2.5) and also on Glassfish v3 (Servlet 3.0). I suspect a bug in Tomcat 7, so I've reported issue 49914about this.
更新：为了排除一个和另一个，我在 Tomcat 7（同时使用和）测试了url-pattern，它确实没有按预期工作。然而，of在 Tomcat 6 (Servlet 2.5) 和 Glassfish v3 (Servlet 3.0) 上按预期工作。我怀疑 Tomcat 7 中存在错误，因此我已报告了有关此问题的 49914。/web.xml@WebFilter(urlPatterns={"/"})url-pattern/
