当调度程序为FORWARD以及调度程序为REQUEST时，如何应用Filter？ [英] How is it possible that Filter is applied when its dispatcher is FORWARD as well as when dispatcher is REQUEST?

问题描述

我有一个简单的过滤器：

I have a simple Filter:

public class TestFilter implements Filter {

    public void init(FilterConfig filterConfig) throws ServletException {
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        System.out.println("before");
        chain.doFilter(request, response);
        System.out.println("after");
    }

    public void destroy() {
    }

}

这是web.xml中的第一个过滤器，它有以下两个映射之一：

It's the first filter in web.xml and it has one of these two mappings:

<filter-mapping>
    <filter-name>cookie-test-filter</filter-name>
    <url-pattern>/*</url-pattern>
    <dispatcher>REQUEST</dispatcher>
</filter-mapping>

或

<filter-mapping>
    <filter-name>cookie-test-filter</filter-name>
    <url-pattern>/*</url-pattern>
    <dispatcher>FORWARD</dispatcher>
</filter-mapping>

在这两种情况下，我都看到了输出：

In both cases I see the output:

before
before
after
after

（我还尝试 INCLUDE 作为调度员只是为了确保一切正常 - 没有输出 INCLUDE ）。

(I've also tried INCLUDE as dispatcher just to be sure that everything works - there's no output with INCLUDE).

这个过滤器之后有第三方过滤器和servlet，我想知道：他们应该做些什么来使我的过滤器应用于所描述的两种情况？

There're 3rd-party filters and servlets after this filter and I wonder: what should they do to make my filter applied in both described cases?

推荐答案

尝试使用单个< filter-mapping> 条目同时请求和 FORWARD 调度员

Try using a single <filter-mapping> entry with both REQUEST and FORWARD dispatcher

示例

<filter-mapping>
    <filter-name>cookie-test-filter</filter-name>
    <url-pattern>/*</url-pattern>
    <dispatcher>REQUEST</dispatcher>
    <dispatcher>FORWARD</dispatcher>
</filter-mapping>

希望这能解决您遇到的问题。

Hope this clears up the issue you were having.

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