自定义标头未插入到 servlet 的请求中

问题描述

有一个第三方应用程序需要通过自定义 http 标头获取信息，因此我编写了一个简单的测试应用程序来创建此标头，然后重定向到列出所有标头的页面.

There's a thrird party app that needs to get information via custom http headers, so I wrote a simple test app that creates this headers and then redirects to a page that lists all headers.

生成标头的 servlet 片段是:

The header-generating servlet snippet is:

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType("text/plain");
    response.setHeader("cust-header", "cust-val");
    response.sendRedirect("header.jsp");
}

另一方面，header.jsp 中的相关代码是:

On the other hand, the relevant code from header.jsp is:

<%
    Enumeration enumeration = request.getHeaderNames();
    while (enumeration.hasMoreElements()) {
    String string = (String)enumeration.nextElement();
    out.println("<font size = 6>" +string +": " + request.getHeader(string)+ "</font><br>");
    }
    %>

显示以下标题:

Host: localhost:9082
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; es-ES; rv:1.9.2.10) Gecko/20100914 Firefox/3.6.10 (.NET CLR 3.5.30729)
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: es-es,es;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 115
Connection: keep-alive
Referer: http://localhost:9082/HdrTest/login.jsp
Cookie: JSESSIONID=0000tubMmZOXDyuM4X9RmaYYTg4:-1

就好像从未插入自定义标题一样.我该如何解决?

As if the custom header was never inserted. How can I fix it ?

谢谢

推荐答案

使用 redirect 您基本上是在指示客户端(网络浏览器)触发一个全新的 HTTP 请求.一个全新的请求也意味着一个全新的回应.将其替换为 forward:

With a redirect you're basically instructing the client (the webbrowser) to fire a brand new HTTP request. A brand new request also means a brand new response. Replace it by a forward:

request.getRequestDispatcher("header.jsp").forward(request, response);

或者如果你真的想在重定向的请求上使用它，那么创建一个映射到 /header.jsp 的 Filter 并相应地修改标头.

Or if you actually want to have it on the redirected request, then create a Filter which is mapped on /header.jsp and modifies the header accordingly.

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws ServletException, IOException {
    ((HttpServletResponse) response).setHeader("foo", "bar");
    chain.doFilter(request, response);
}

另请注意，您在 header.jsp 中显示 request 标头，而不是 response 标头.由于没有可用的直接 API 来显示响应标头，因此您希望使用外部 HTTP 标头嗅探工具(例如 Firebug(Net 面板)或 提琴手.

Also note that you're displaying the request headers in the header.jsp instead of response headers. Since there's no direct API avaliable to display the response headers, you'd like to investigate them using an external HTTP header sniffing tool like Firebug (the Net panel) or Fiddler.

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