Servlet:提交响应后无法转发

2022-01-14 00:00:00 geolocation java servlets response.redirect forward

我正在开发基于 geo-location 呈现内容的 servlet 页面，我想同时使用 sendRedirect 和 forward;例如;您从 France 浏览 example.com/aPage.jsp；首先，我希望 servlet 将您重定向到 example.com/fr/aPage.jsp，然后将您转发到 resources 页面.

I'm working on servlet page that renders content based on geo-location, and I want to use both sendRedirect and forward together; e.g; you browse example.com/aPage.jsp from France; first I want the servlet to redirect you to example.com/fr/aPage.jsp and then forward you to the resources page.

这就是我的 servlet 中的内容:

This is what I have in my servlet:

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  ....
  response.sendRedirect(REDIRECT_URL_BASED_ON_GEO);
  // after redirect forward the resources page
  RequestDispatcher view = request.getRequestDispatcher(RESOURCES_PAGE);
  view.forward(request, response);
  ...
}

但我明白了:

java.lang.IllegalStateException: Cannot forward after response has been committed

我知道错误出现是因为我不能同时使用 sendRedirect 和 forward 一个又一个，但我不知道如何在没有这个的情况下实现我想要的(如上所述).

I know the error appears because I can't use both sendRedirect and forward one after another, but I don't know how to achieve what I want (as described above) without this.

有什么帮助吗?

推荐答案

 response.sendRedirect(REDIRECT_URL_BASED_ON_GEO);
  // after redirect forward the resources page

在那一行之后，您的回复开始写入 clinet.

After that line , Your response start writing to clinet.

您正在尝试向其中添加其他数据.

And you are trying to add additional data to it.

服务器已经完成响应头的写入，并且正在写入内容的正文，以及您尝试在标题中写入更多内容的点 - 当然它不能倒带.

The server has already finished writing the response header and is writing the body of the content, and which point you are trying to write more to the header - of course it cant rewind.

所以，处理 servlet 时的拇指规则是

So,Thumb rule while dealing with servlet is

在redirect或forward添加return语句之前完成你的逻辑.所以执行到此结束.

Finish your logic before redirect or forward add return statement.So execution ends there .

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