An URI as http://example.com/users/delete/6 is a very bad example of REST API implementation. It should be http://example.com/users/6 and handle the DELETE method to remove the user with id 6.

A smart solution to keep the API clean, is overriding the original method with one specified in a request header. So a POST method can act as PUT or DELETE method adding a known header to the request. The X-HTTP-Method-Override is the header that is used to to that

The java sourcecode:

/**
 *
 * @author Filippo De Luca
 *
 * @version $Id$
 */
public class MethodOverrideFilter implements Filter {

	public static final String HEADER_PARAM = "methodOverrideHeader";

	public static final String DEFAULT_HEADER = "X-HTTP-Method-Override";

	private String header = DEFAULT_HEADER;

	public void init(FilterConfig filterConfig) throws ServletException {

		header = filterConfig.getInitParameter(HEADER_PARAM);
		if(StringUtils.isBlank(header)) {
			header = DEFAULT_HEADER;
		}

	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {

		ServletRequest filteredRequest = request;

		if(request instanceof HttpServletRequest) {

			HttpServletRequest httpRequest = (HttpServletRequest)request;
			filteredRequest = new MethodOverrideHttpServletRequestDecorator(httpRequest, header);
		}

		chain.doFilter(filteredRequest, response);
	}

	public void destroy() {
		// Empty
	}

}

/**
 * @author Filippo De Luca
 *
 * @version $Id$
 */
public class MethodOverrideHttpServletRequestDecorator extends
		HttpServletRequestWrapper {

	public static final String DEFAULT_HEADER = "X-HTTP-Method-Override";

	private final String methodOverrideHeader;

	private transient String method;

	/**
	 * @param request
	 */
	public MethodOverrideHttpServletRequestDecorator(HttpServletRequest request, String methodOverrideHeader) {
		super(request);
		this.methodOverrideHeader = methodOverrideHeader;
	}

	@Override
	public String getMethod() {

		if(method==null) {
			method = resolveMethod();
		}

		return method;
	}

	protected String resolveMethod() {

		String headerValue = getHeader(methodOverrideHeader);

		if(headerValue!=null) {
			return headerValue;
		}
		else {
			return super.getMethod();
		}
	}

}