Servlet过滤器：如何从ServletRequest中获取所有标头？

Question

这是我的WebFilter模样

@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() {
    }
}

我试图在线查找有关如何HTTP headers从请求中获取价值的信息。

我什么也没找到，所以我尝试枚举，servletRequest.getAttributeNames()并且servletRequest.getParameterNames()一无所知，但是没有任何标题。

问题
如何获得来自请求的所有标头？

Answer 1

类型转换ServletRequest成HttpServletRequest（仅当ServletRequest request是一个instanceof HttpServletRequest）。

然后可以使用HttpServletRequest.getHeader()和HttpServletRequest.getHeaderNames()方法。

像这样：

@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);
}