How to set a parameter in a HttpServletRequest?

Question

I am using a javax.servlet.http.HttpServletRequest to implement a web application.

I have no problem to get the parameter of a request using the getParamete

Answer 1

The most upvoted solution generally works but for Spring and/or Spring Boot, the values will not wire to parameters in controller methods annotated with @RequestParam unless you specifically implemented getParameterValues(). I combined the solution(s) here and from this blog:

import java.util.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class MutableHttpRequest extends HttpServletRequestWrapper {

    private final Map mutableParams = new HashMap<>();

    public MutableHttpRequest(final HttpServletRequest request) {
        super(request);
    }

    public MutableHttpRequest addParameter(String name, String value) {
        if (value != null)
            mutableParams.put(name, new String[] { value });

        return this;
    }

    @Override
    public String getParameter(final String name) {
        String[] values = getParameterMap().get(name);

        return Arrays.stream(values)
                .findFirst()
                .orElse(super.getParameter(name));
    }

    @Override
    public Map getParameterMap() {
        Map allParameters = new HashMap<>();
        allParameters.putAll(super.getParameterMap());
        allParameters.putAll(mutableParams);

        return Collections.unmodifiableMap(allParameters);
    }

    @Override
    public Enumeration getParameterNames() {
        return Collections.enumeration(getParameterMap().keySet());
    }

    @Override
    public String[] getParameterValues(final String name) {
        return getParameterMap().get(name);
    }
}

note that this code is not super-optimized but it works.