CODEWITHSUNDEEP
springfilterhttp-headers
cdugga
cdugga

Reputation: 3859

Setting HTTP header in DelegatingFilterProxy

I have a filter , I'm using Springs delegatingFilterProxy to intercept incoming requests for a web service. Depending on whether a flag is set i want to allow the request to continue otherwise i want to set a request header which when checked by the endpoint will indicate whether to allow the request to continue or not. I want to place the code in the filter to abstract the logic of checking the flag.

How can i modify the request header in a filter (simple code example would be great) and is it acceptable practice, or should i be sending the response from the filter instead of pushing the decision down to the endpoint? 

   public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
if(somecondition)
    set request header and forward to endpoint
else 
    forward to endpoint without extra header

Thanks

Upvotes: 1

Views: 1784

Answers (2)

mrembisz
mrembisz

Reputation: 12880

Request attributes are better suited for this purpose ServletRequest.get/setAttribute(). Is there any reason you cannot use them?

Upvotes: 1

Arun P Johny
Arun P Johny

Reputation: 388446

You need to create a FakeRequest to solve it

FakeHeadersRequest

import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

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

public class FakeHeadersRequest extends HttpServletRequestWrapper {

    private Map<String, List<String>> headers = new HashMap<String, List<String>>();

    public FakeHeadersRequest(HttpServletRequest request) {
        super(request);
    }

    @Override
    public String getHeader(String name) {
        if (headers.containsKey(name)) {
            return headers.get(name).get(0);
        }

        return super.getHeader(name);
    }

    public void addHeader(String header, String value) {
        List<String> list = headers.get(header);
        if (list == null) {
            list = new ArrayList<String>();
            headers.put(header, list);
        }
        list.add(value);
    }

    public void setHeader(String header, String value) {
        List<String> list = new ArrayList<String>();
        headers.put(header, list);
        list.add(value);
    }

    @SuppressWarnings({ "rawtypes", "unchecked" })
    @Override
    public Enumeration getHeaderNames() {
        List<String> list = new ArrayList<String>();

        HttpServletRequest request = (HttpServletRequest) getRequest();
        Enumeration<String> e = request.getHeaderNames();
        while (e.hasMoreElements()) {
            list.add(e.nextElement());
        }

        list.addAll(headers.keySet());

        return Collections.enumeration(list);
    }
}

FakeHeaderFilter

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

public class FakeHeaderFilter implements Filter {
    public void init(FilterConfig filterConfig) {
    }

    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        boolean condition = false;
        if (condition && request instanceof HttpServletRequest) {
            FakeHeadersRequest req = new FakeHeadersRequest(
                    (HttpServletRequest) request);
            req.setHeader("new-header", "some-value");
            chain.doFilter(req, response);
        } else {
            chain.doFilter(request, response);
        }

    }

    public void destroy() {
    }

}

Also refer this

Upvotes: 2

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