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I am working on an application that has to download some external resources and make them accessible through a public/static directory in Ring.

But.. I have a problem saving the resources into a static directory in my application, when developing I use the ring-jetty-adapter; the test & production servers are running Tomcat.

I added :web-content "public" to my leiningen project and added the public directory in the root of the project, then I have a download function using http-agent and duck-streams:

(defn download
  [file-name url]
  (h/http-agent url
                :handler (fn [agnt]
                           (let [fname file-name]
                             (with-open [w (d/writer fname)]
                               (d/copy (h/stream agnt) w))))))

If I am booting Jetty from the REPL and use savepath: "public/my.file", the downloaded file is placed correctly in the public directory. But when I deploy it using a .war file to Tomcat, it looks for a public directory in the Tomcat root directory, and not under the application context path.

I tried to add a middleware wrapper to determine the context path and from there build the correct save path, but I cannot find any way to access the HttpServlet or a way to determine if the application is running in the adapter or if it is deployed under a specific context.

Here the wrapper:

(defn wrap-context-info [handler]
  (fn [req]
    (let [resp (handler req)]
      (assoc resp :servlet (:servlet req) :req (:servlet-request  req)))))

both :servlet and :req are nil.

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1 回答 1

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查看ring-servlet 源，似乎 ring servlet 适配器将HttpServlet、HttpServletRequest和对象与相应的、和键HttpServletResponse下的环请求映射相关联。:servlet:servlet-request:servlet-response

为方便起见，它还:servlet-context在请求映射中添加了一个值为 的条目。(.getServletContext servlet)

在您的处理程序中，您可能希望检查请求映射中是否存在这些键，然后从关联对象中提取您需要的更多信息。

于 2010-11-26T13:18:40.730 回答