org.springframework.web.accept.ServletPathExtensionContentNegotiationStrategy.java Source code

Introduction

Here is the source code for org.springframework.web.accept.ServletPathExtensionContentNegotiationStrategy.java

Source

/*
 * 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.accept;

import java.util.Map;
import javax.servlet.ServletContext;

import org.springframework.core.io.Resource;
import org.springframework.http.MediaType;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
import org.springframework.web.HttpMediaTypeNotAcceptableException;
import org.springframework.web.context.request.NativeWebRequest;

/**
 * Extends {@code PathExtensionContentNegotiationStrategy} that also uses
 * {@link ServletContext#getMimeType(String)} to resolve file extensions.
 *
 * @author Rossen Stoyanchev
 * @since 3.2
 */
public class ServletPathExtensionContentNegotiationStrategy extends PathExtensionContentNegotiationStrategy {

    private final ServletContext servletContext;

    /**
     * Create an instance without any mappings to start with. Mappings may be
     * added later when extensions are resolved through
     * {@link ServletContext#getMimeType(String)} or via
     * {@link org.springframework.http.MediaTypeFactory}.
     */
    public ServletPathExtensionContentNegotiationStrategy(ServletContext context) {
        this(context, null);
    }

    /**
     * Create an instance with the given extension-to-MediaType lookup.
     */
    public ServletPathExtensionContentNegotiationStrategy(ServletContext servletContext,
            @Nullable Map<String, MediaType> mediaTypes) {

        super(mediaTypes);
        Assert.notNull(servletContext, "ServletContext is required");
        this.servletContext = servletContext;
    }

    /**
     * Resolve file extension via {@link ServletContext#getMimeType(String)}
     * and also delegate to base class for a potential
     * {@link org.springframework.http.MediaTypeFactory} lookup.
     */
    @Override
    @Nullable
    protected MediaType handleNoMatch(NativeWebRequest webRequest, String extension)
            throws HttpMediaTypeNotAcceptableException {

        MediaType mediaType = null;
        String mimeType = this.servletContext.getMimeType("file." + extension);
        if (StringUtils.hasText(mimeType)) {
            mediaType = MediaType.parseMediaType(mimeType);
        }
        if (mediaType == null || MediaType.APPLICATION_OCTET_STREAM.equals(mediaType)) {
            MediaType superMediaType = super.handleNoMatch(webRequest, extension);
            if (superMediaType != null) {
                mediaType = superMediaType;
            }
        }
        return mediaType;
    }

    /**
     * Extends the base class
     * {@link PathExtensionContentNegotiationStrategy#getMediaTypeForResource}
     * with the ability to also look up through the ServletContext.
     * @param resource the resource to look up
     * @return the MediaType for the extension, or {@code null} if none found
     * @since 4.3
     */
    @Override
    public MediaType getMediaTypeForResource(Resource resource) {
        MediaType mediaType = null;
        String mimeType = this.servletContext.getMimeType(resource.getFilename());
        if (StringUtils.hasText(mimeType)) {
            mediaType = MediaType.parseMediaType(mimeType);
        }
        if (mediaType == null || MediaType.APPLICATION_OCTET_STREAM.equals(mediaType)) {
            MediaType superMediaType = super.getMediaTypeForResource(resource);
            if (superMediaType != null) {
                mediaType = superMediaType;
            }
        }
        return mediaType;
    }

}