name.cphillipson.experimental.gwt.server.interceptor.DateTimeZoneHandlerInterceptor.java Source code

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Here is the source code for name.cphillipson.experimental.gwt.server.interceptor.DateTimeZoneHandlerInterceptor.java

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/*
 * Copyright 2010 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 name.cphillipson.experimental.gwt.server.interceptor;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.joda.time.DateTimeZone;
import org.springframework.format.datetime.joda.JodaTimeContext;
import org.springframework.format.datetime.joda.JodaTimeContextHolder;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.util.WebUtils;

/**
 * Spring MVC Interceptor that sets the request's {@link DateTimeZone} from a cookie.
 * Allows the client's timezone to be figured out by JavaScript, then submitted and applied on the server as the default timezone for the request.
 * Useful when you need to render dates in client local time.
 * @author Keith Donald
 */
public class DateTimeZoneHandlerInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        final JodaTimeContext context = new JodaTimeContext();
        context.setTimeZone(getTimeZone(request));
        JodaTimeContextHolder.setJodaTimeContext(context);
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        if (modelAndView != null) {
            modelAndView.addObject("jodaTimeContext", JodaTimeContextHolder.getJodaTimeContext());
        }
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler,
            Exception ex) throws Exception {
        JodaTimeContextHolder.resetJodaTimeContext();
    }

    // internal helpers

    private DateTimeZone getTimeZone(HttpServletRequest request) {
        final Integer millisOffset = getMillisOffset(request);
        if (millisOffset != null) {
            try {
                return DateTimeZone.forOffsetMillis(millisOffset);
            } catch (final IllegalArgumentException e) {
                return DateTimeZone.getDefault();
            }
        } else {
            return DateTimeZone.getDefault();
        }
    }

    private Integer getMillisOffset(HttpServletRequest request) {
        final Cookie cookie = WebUtils.getCookie(request, "emkt.timeZoneOffset");
        if (cookie != null) {
            return Integer.valueOf(cookie.getValue());
        } else {
            return null;
        }
    }

}