nu.yona.server.rest.LocalizationFilter.java Source code

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Here is the source code for nu.yona.server.rest.LocalizationFilter.java

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/*******************************************************************************
 * Copyright (c) 2016 Stichting Yona Foundation
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 *******************************************************************************/
package nu.yona.server.rest;

import java.io.IOException;
import java.util.Locale;

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;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpHeaders;
import org.springframework.stereotype.Component;

import nu.yona.server.Translator;
import nu.yona.server.properties.YonaProperties;

@Component
/**
 * This servlet filter ensures that it looks like any request always specifies a supported locale, and it adds the
 * Content-Language header to the responses. The request handling is is done by wrapping every request with a wrapper that
 * intercepts the getLocale operation. If the locale of the request does not match a supported locale, the default locale is
 * returned. The Content-Language header simply added added to response headers before passing the request and response to the
 * next filter.
 */
public class LocalizationFilter implements Filter {
    public static class LocalizationRequestWrapper extends HttpServletRequestWrapper {
        private final Locale locale;
        private YonaProperties properties;

        public LocalizationRequestWrapper(YonaProperties properties, HttpServletRequest request) {
            super(request);
            this.properties = properties;
            this.locale = determineLocale(request.getLocale());
        }

        @Override
        public Locale getLocale() {
            return locale;
        }

        private Locale determineLocale(Locale requestLocale) {
            if (properties.getSupportedLocales().contains(requestLocale)) {
                return requestLocale;
            }
            return properties.getDefaultLocale();
        }
    }

    @Autowired
    private YonaProperties properties;

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain)
            throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;

        request = new LocalizationRequestWrapper(properties, request);
        response.setHeader(HttpHeaders.CONTENT_LANGUAGE, Translator.getStandardLocaleString(request.getLocale()));

        chain.doFilter(request, response);
    }

    @Override
    public void destroy() {
        // Nothing to do here
    }

    @Override
    public void init(FilterConfig config) throws ServletException {
        // Nothing to do here
    }
}