org.springframework.boot.autoconfigure.web.servlet.WelcomePageHandlerMapping.java Source code

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Here is the source code for org.springframework.boot.autoconfigure.web.servlet.WelcomePageHandlerMapping.java

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/*
 * Copyright 2012-2018 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.boot.autoconfigure.web.servlet;

import java.util.Collections;
import java.util.List;
import java.util.Optional;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.boot.autoconfigure.template.TemplateAvailabilityProviders;
import org.springframework.context.ApplicationContext;
import org.springframework.core.io.Resource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.handler.AbstractUrlHandlerMapping;
import org.springframework.web.servlet.mvc.ParameterizableViewController;

/**
 * An {@link AbstractUrlHandlerMapping} for an application's welcome page. Supports both
 * static and templated files. If both a static and templated index page are available,
 * the static page is preferred.
 *
 * @author Andy Wilkinson
 * @author Bruce Brouwer
 */
final class WelcomePageHandlerMapping extends AbstractUrlHandlerMapping {

    private static final Log logger = LogFactory.getLog(WelcomePageHandlerMapping.class);

    private static final List<MediaType> MEDIA_TYPES_ALL = Collections.singletonList(MediaType.ALL);

    WelcomePageHandlerMapping(TemplateAvailabilityProviders templateAvailabilityProviders,
            ApplicationContext applicationContext, Optional<Resource> welcomePage, String staticPathPattern) {
        if (welcomePage.isPresent() && "/**".equals(staticPathPattern)) {
            logger.info("Adding welcome page: " + welcomePage.get());
            setRootViewName("forward:index.html");
        } else if (welcomeTemplateExists(templateAvailabilityProviders, applicationContext)) {
            logger.info("Adding welcome page template: index");
            setRootViewName("index");
        }
    }

    private boolean welcomeTemplateExists(TemplateAvailabilityProviders templateAvailabilityProviders,
            ApplicationContext applicationContext) {
        return templateAvailabilityProviders.getProvider("index", applicationContext) != null;
    }

    private void setRootViewName(String viewName) {
        ParameterizableViewController controller = new ParameterizableViewController();
        controller.setViewName(viewName);
        setRootHandler(controller);
        setOrder(2);
    }

    @Override
    public Object getHandlerInternal(HttpServletRequest request) throws Exception {
        for (MediaType mediaType : getAcceptedMediaTypes(request)) {
            if (mediaType.includes(MediaType.TEXT_HTML)) {
                return super.getHandlerInternal(request);
            }
        }
        return null;
    }

    private List<MediaType> getAcceptedMediaTypes(HttpServletRequest request) {
        String acceptHeader = request.getHeader(HttpHeaders.ACCEPT);
        if (StringUtils.hasText(acceptHeader)) {
            return MediaType.parseMediaTypes(acceptHeader);
        }
        return MEDIA_TYPES_ALL;
    }

}