java为什么@RequestHeader无法捕获过滤器中添加的自定义标头

Question

为什么我不在方法参数@RequestHeader("Custom-Header")中获取值，尽管我在@RequestHeader Map<String,String> headers中获取它

最初，请求到达服务器时没有“自定义头”，我将其添加到过滤器中。之后，请求落入方法中，但spring无法在参数@RequestHeader（“自定义头”）中插入头。为什么?

方法：

    @PostMapping("/support")
        public SupportView sendEmailToSupport(/*@Validated MessageView supportView,*/
                @RequestHeader Map<String, String> headers, //there is a header
                @RequestHeader(value = CUSTOM_HEADER, required = false) String customHeader) { //but not here
            SupportView supportView = helpDeskService.sendEmailToSupport(null, customHeader);
            return supportView;
        }

过滤器：

public class HeaderChangerFilter implements Filter {

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        MutableHttpServletRequestWrapper request = new MutableHttpServletRequestWrapper((HttpServletRequest) servletRequest);

        String oldHeaderValue = request.getHeader(OLD_HEADER);
        String newHeaderValue = request.getHeader(CUSTOM_HEADER);

        if (oldHeaderValue != null && newHeaderValue == null) {
            request.putHeader(CUSTOM_HEADER, RequestHeaderUtils.getOldHeaderValue(request));
        }

        filterChain.doFilter(request, servletResponse); //CUSTOM_HEADER has in request headers
    }}

请求授权：

import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class MutableHttpServletRequestWrapper extends HttpServletRequestWrapper {
    // holds a custom header and value mapping
    private final Map<String, String> customHeaders;

    public MutableHttpServletRequestWrapper(HttpServletRequest request){
        super(request);
        this.customHeaders = new HashMap<>();
    }

    public void putHeader(String name, String value){
        this.customHeaders.put(name, value);
    }

    @Override
    public String getHeader(String name) {
        // check the custom headers first
        String headerValue = customHeaders.get(name);

        if (headerValue != null){
            return headerValue;
        }
        // else return from into the original wrapped object
        return ((HttpServletRequest) getRequest()).getHeader(name);
    }

    @Override
    public Enumeration<String> getHeaderNames() {
        // create a set of the custom header names
        Set<String> set = new HashSet<>(customHeaders.keySet());

        // now add the headers from the wrapped request object
        Enumeration<String> e = ((HttpServletRequest) getRequest()).getHeaderNames();
        while (e.hasMoreElements()) {
            // add the names of the request headers into the list
            String n = e.nextElement();
            set.add(n);
        }

        // create an enumeration from the set and return
        return Collections.enumeration(set);
    }
}

Answer 1

您可以重写getHeaders（）方法

@Override
public Enumeration<String> getHeaders(String name) {
    String values = getHeader(name);
    Set<String> set = Arrays.asList(values.split(",")).stream().collect(Collectors.toSet());
    if (customHeaders.containsKey(name)) {
       return Collections.enumeration(set);
    }
    return super.getHeaders(name);
}