我需要在每个响应中添加标题。我打算在下面做
public class MyFilter extends OncePerRequestFilter { @Override protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException { filterChain.doFilter(request, response); response.addHeader("Access-Control-Allow-Origin", "*"); } }
我想这样做,filterChain.doFilter(request,response)以便一旦控制器处理它,我只需在返回客户端之前添加标头即可。这是对的吗 ?
filterChain.doFilter(request,response)
之后chain.doFilter又回来了,这是来不及做的任何回应。此时,整个响应已发送到客户端,您的代码无法访问它。
chain.doFilter
以上声明对我而言并不正确。之后filterChain.doFilter(request, response)是否可以添加标题?如果不是为什么?
filterChain.doFilter(request, response)
我正在使用Spring MVC。
filterChain.doFilter被调用之后,对响应进行任何操作为时已晚。此时,整个响应已经发送给客户端。
filterChain.doFilter
您需要在自己的类中构建包装响应,将这些包装传递给doFilter方法,并处理包装中的所有处理。
doFilter
已经有一个响应包装器:HttpServletResponseWrapper您可以扩展。例如:
HttpServletResponseWrapper
public class MyResponseRequestWrapper extends HttpServletResponseWrapper{ public MyResponseRequestWrapper(HttpServletResponse response) { super(response); } }
您的过滤器:
@Override protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException { HttpServletResponse myResponse = (HttpServletResponse) response; MyResponseRequestWrapper responseWrapper = new MyResponseRequestWrapper(myResponse); responseWrapper.addHeader("Access-Control-Allow-Origin", "*"); filterChain.doFilter(request, myResponse); }