org.springframework.web.servlet.theme.SessionThemeResolver.java Source code

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Here is the source code for org.springframework.web.servlet.theme.SessionThemeResolver.java

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/*
 * Copyright 2002-2017 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
 *
 *      https://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.servlet.theme;

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

import org.springframework.lang.Nullable;
import org.springframework.util.StringUtils;
import org.springframework.web.util.WebUtils;

/**
 * {@link org.springframework.web.servlet.ThemeResolver} implementation that
 * uses a theme attribute in the user's session in case of a custom setting,
 * with a fallback to the default theme. This is most appropriate if the
 * application needs user sessions anyway.
 *
 * <p>Custom controllers can override the user's theme by calling
 * {@code setThemeName}, e.g. responding to a theme change request.
 *
 * @author Jean-Pierre Pawlak
 * @author Juergen Hoeller
 * @since 17.06.2003
 * @see #setThemeName
 */
public class SessionThemeResolver extends AbstractThemeResolver {

    /**
     * Name of the session attribute that holds the theme name.
     * Only used internally by this implementation.
     * Use {@code RequestContext(Utils).getTheme()}
     * to retrieve the current theme in controllers or views.
     * @see org.springframework.web.servlet.support.RequestContext#getTheme
     * @see org.springframework.web.servlet.support.RequestContextUtils#getTheme
     */
    public static final String THEME_SESSION_ATTRIBUTE_NAME = SessionThemeResolver.class.getName() + ".THEME";

    @Override
    public String resolveThemeName(HttpServletRequest request) {
        String themeName = (String) WebUtils.getSessionAttribute(request, THEME_SESSION_ATTRIBUTE_NAME);
        // A specific theme indicated, or do we need to fallback to the default?
        return (themeName != null ? themeName : getDefaultThemeName());
    }

    @Override
    public void setThemeName(HttpServletRequest request, @Nullable HttpServletResponse response,
            @Nullable String themeName) {

        WebUtils.setSessionAttribute(request, THEME_SESSION_ATTRIBUTE_NAME,
                (StringUtils.hasText(themeName) ? themeName : null));
    }

}