是否可以僅從使用 Java 流的集合中獲取特定數據？

Question

我有以下代碼：

 @Override
      public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        HttpHeaders httpHeaders = Collections.list(httpServletRequest.getHeaderNames())
          .stream()
          .collect(Collectors.toMap(
            Function.identity(),
            h -> Collections.list(httpServletRequest.getHeaders(h)),
            (oldValue, newValue) -> newValue,
            HttpHeaders::new
          ));
        System.out.println(httpHeaders);
          chain.doFilter(request, response);
      }

它工作得很好，但我只需要獲取一些特定的數據，比如接受編碼和接受語言。 有可能以某種方式做到這一點嗎？

Answer 1

一種可能的解決方案

List<String> headerNames = Arrays.asList("Accept-Encoding", "Content-Type");
Map<String, String> headers = headerNames.stream()
     .collect(Collectors.toMap(Function.identity(), header -> httpServletRequest.getHeader(header)));

或者如果你想得到 HttpHeaders 結果

List<String> headers = Arrays.asList("Accept-Encoding", "Content-Type");
HttpHeaders httpHeaders = new HttpHeaders();
headers.forEach(header -> {
    request.getHeaders(header)
             .asIterator()
             .forEachRemaining(value -> httpHeaders.add(header, value));
});