我可以从 <url-pattern> 中排除一些具体的 url 吗?在 <filter-mapping> 里面? [英] Can I exclude some concrete urls from <url-pattern> inside <filter-mapping>?

问题描述

我希望对除一个具体之外的所有 url 应用一些具体过滤器(即对于 /*，除了 /specialpath).

I want some concrete filter to be applied for all urls except for one concrete (i.e. for /* except for /specialpath).

有没有可能做到这一点?

Is there a possibility to do that?

示例代码:

<filter>
    <filter-name>SomeFilter</filter-name>
    <filter-class>org.somproject.AFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>SomeFilter</filter-name>
    <url-pattern>/*</url-pattern>   <!-- the question is: how to modify this line?  -->
    <dispatcher>REQUEST</dispatcher>
    <dispatcher>FORWARD</dispatcher>
</filter-mapping>

推荐答案

标准 Servlet API 不支持此功能.您可能希望为此使用重写 URL 过滤器，例如 Tuckey 的过滤器(这与 Apache HTTPD 的 mod_rewrite)，或者在/*上监听Filter的doFilter()方法中添加一个检查.

The standard Servlet API doesn't support this facility. You may want either to use a rewrite-URL filter for this like Tuckey's one (which is much similar Apache HTTPD's mod_rewrite), or to add a check in the doFilter() method of the Filter listening on /*.

String path = ((HttpServletRequest) request).getRequestURI();
if (path.startsWith("/specialpath/")) {
    chain.doFilter(request, response); // Just continue chain.
} else {
    // Do your business stuff here for all paths other than /specialpath.
}

如有必要，您可以将要忽略的路径指定为过滤器的 init-param，以便您无论如何都可以在 web.xml 中控制它.您可以按如下方式在过滤器中获取它:

You can if necessary specify the paths-to-be-ignored as an init-param of the filter so that you can control it in the web.xml anyway. You can get it in the filter as follows:

private String pathToBeIgnored;

public void init(FilterConfig config) {
    pathToBeIgnored = config.getInitParameter("pathToBeIgnored");
}

如果过滤器是第 3 方 API 的一部分，因此您无法修改它，则将其映射到更具体的 url-pattern，例如/otherfilterpath/* 并在 /* 上创建一个新的过滤器，它转发到与第 3 方过滤器匹配的路径.

If the filter is part of 3rd party API and thus you can't modify it, then map it on a more specific url-pattern, e.g. /otherfilterpath/* and create a new filter on /* which forwards to the path matching the 3rd party filter.

String path = ((HttpServletRequest) request).getRequestURI();
if (path.startsWith("/specialpath/")) {
    chain.doFilter(request, response); // Just continue chain.
} else {
    request.getRequestDispatcher("/otherfilterpath" + path).forward(request, response);
}

为避免此过滤器在无限循环中调用自身，您需要让它仅在 REQUEST 上侦听(调度)，并且仅在 FORWARD 上监听(调度)第 3 方过滤器.

To avoid that this filter will call itself in an infinite loop you need to let it listen (dispatch) on REQUEST only and the 3rd party filter on FORWARD only.

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