/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.filter;

import java.io.IOException;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.http.HttpStatus;
import org.springframework.util.Assert;

Overrides HttpServletResponse.sendRedirect(String) and handles it by setting the HTTP status and "Location" headers, which keeps the Servlet container from re-writing relative redirect URLs into absolute ones. Servlet containers are required to do that but against the recommendation of  RFC 7231 Section 7.1.2,
and furthermore not necessarily taking into account "X-Forwarded" headers.
Note: While relative redirects are recommended in the
RFC, under some configurations with reverse proxies they may not work.
Author:
Rob Winch, Rossen Stoyanchev
Since:
4.3.10/**
 * Overrides {@link HttpServletResponse#sendRedirect(String)} and handles it by
 * setting the HTTP status and "Location" headers, which keeps the Servlet
 * container from re-writing relative redirect URLs into absolute ones.
 * Servlet containers are required to do that but against the recommendation of
 * <a href="https://tools.ietf.org/html/rfc7231#section-7.1.2"> RFC 7231 Section 7.1.2</a>,
 * and furthermore not necessarily taking into account "X-Forwarded" headers.
 *
 * <p><strong>Note:</strong> While relative redirects are recommended in the
 * RFC, under some configurations with reverse proxies they may not work.
 *
 * @author Rob Winch
 * @author Rossen Stoyanchev
 * @since 4.3.10
 */
public class RelativeRedirectFilter extends OncePerRequestFilter {

	private HttpStatus redirectStatus = HttpStatus.SEE_OTHER;


	
Set the default HTTP Status to use for redirects.
By default this is HttpStatus.SEE_OTHER. 
Params:
status – the 3xx redirect status to use/**
	 * Set the default HTTP Status to use for redirects.
	 * <p>By default this is {@link HttpStatus#SEE_OTHER}.
	 * @param status the 3xx redirect status to use
	 */
	public void setRedirectStatus(HttpStatus status) {
		Assert.notNull(status, "Property 'redirectStatus' is required");
		Assert.isTrue(status.is3xxRedirection(), "Not a redirect status code");
		this.redirectStatus = status;
	}

	
Return the configured redirect status.
/**
	 * Return the configured redirect status.
	 */
	public HttpStatus getRedirectStatus() {
		return this.redirectStatus;
	}


	@Override
	protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
			FilterChain filterChain) throws ServletException, IOException {

		response = RelativeRedirectResponseWrapper.wrapIfNecessary(response, this.redirectStatus);
		filterChain.doFilter(request, response);
	}

}