通过过滤器向请求添加自定义标头

问题描述：

我有一个扩展Filter类的类，它看起来像:

I have a class which extend Filter class and it looks like:

@Component
@Order(Ordered.HIGHEST_PRECEDENCE)
public class CorsFilter implements Filter {

    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        System.out.println("--------------------------------------");

        HttpServletRequest request = (HttpServletRequest) req;

        req.setAttribute("test", "test");


        final HttpServletResponse response = (HttpServletResponse) res;
        response.setHeader("Access-Control-Allow-Origin", "*");
        response.setHeader("Access-Control-Allow-Methods", "POST, PUT, GET, OPTIONS, DELETE");
        response.setHeader("Access-Control-Allow-Headers", "Authorization, Content-Type");
        response.setHeader("Access-Control-Max-Age", "3600");
        if ("OPTIONS".equalsIgnoreCase(((HttpServletRequest) req).getMethod())) {
            response.setStatus(HttpServletResponse.SC_OK);
        } else {
            chain.doFilter(req, res);
        }
    }

问题是我可以向request添加自定义header吗?我经历了request和req内部可用的所有方法，找不到任何方法.但是在debug模式下，我发现CoyoteRequest内是headers的列表.如何在其中添加自定义header?

The question is can I add a custom header to request? I went through all method which are available inside request and req and couldn't find any way. But in debug mode I found that inside CoyoteRequest is list of headers. How can I add there my custom header?

答

您不能在HttpServletRequest对象中设置标头，但可以使用包装器类.

You can not set the headers in HttpServletRequestobject, but you can use a wrapper class.

请参阅本指南: http://wilddiary.com/adding-custom- headers-java-httpservletrequest/

以防万一将来链接无效:

Just in case for future the link becomes invalid:

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

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

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

    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);
    }

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

        // now add the headers from the wrapped request object
        @SuppressWarnings("unchecked")
        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);
    }
}

用法:

@Override
public void doFilter(ServletRequest request, ServletResponse response,
        FilterChain chain) throws IOException, ServletException {
    HttpServletRequest req = (HttpServletRequest) request;
    MutableHttpServletRequest mutableRequest = new MutableHttpServletRequest(req);
    ...
    mutableRequest.putHeader("x-custom-header", "custom value");
    chain.doFilter(mutableRequest, response);
}

通过过滤器向请求添加自定义标头

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