java - Servlet 过滤器 : How to get all the headers from servletRequest?

Question

这是我的 WebFilter 的样子

@WebFilter("/rest/*")
public class AuthTokenValidatorFilter implements Filter {

    @Override
    public void init(final FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void doFilter(final ServletRequest servletRequest, final ServletResponse servletResponse, final FilterChain filterChain) throws IOException, ServletException {
        final Enumeration<String> attributeNames = servletRequest.getAttributeNames();
        while (attributeNames.hasMoreElements()) {
            System.out.println("{attribute} " + servletRequest.getParameter(attributeNames.nextElement()));
        }

        final Enumeration<String> parameterNames = servletRequest.getParameterNames();
        while (parameterNames.hasMoreElements()) {
            System.out.println("{parameter} " + servletRequest.getParameter(parameterNames.nextElement()));
        }
        filterChain.doFilter(servletRequest, servletResponse);
    }

    @Override
    public void destroy() {
    }
}

我试图在网上了解如何从请求中获取 HTTP header 的值。

我没有找到任何东西，所以我尝试在不知道任何东西的情况下枚举 servletRequest.getAttributeNames() 和 servletRequest.getParameterNames()，但我没有得到任何标题。

问题
如何获取请求中的所有 header ？

Answer 1

Typecast ServletRequest 到 HttpServletRequest (仅当 ServletRequest request 是 instanceof HttpServletRequest)。

然后就可以使用HttpServletRequest.getHeader()和HttpServletRequest.getHeaderNames()方法了。

类似这样的:

@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    HttpServletRequest httpRequest = (HttpServletRequest) request;
    Enumeration<String> headerNames = httpRequest.getHeaderNames();

    if (headerNames != null) {
            while (headerNames.hasMoreElements()) {
                    System.out.println("Header: " + httpRequest.getHeader(headerNames.nextElement()));
            }
    }

    //doFilter
    chain.doFilter(httpRequest, response);
}