/**
* Determines the {@link MediaType} for the given filename.
*
* <p>The default implementation will check the {@linkplain #setMediaTypes(Map) media types}
* property first for a defined mapping. If not present, and if the Java Activation Framework can
* be found on the classpath, it will call {@link FileTypeMap#getContentType(String)}
*
* <p>This method can be overridden to provide a different algorithm.
*
* @param filename the current request file name (i.e. {@code hotels.html})
* @return the media type, if any
*/
protected MediaType getMediaTypeFromFilename(String filename) {
String extension = StringUtils.getFilenameExtension(filename);
if (!StringUtils.hasText(extension)) {
return null;
}
extension = extension.toLowerCase(Locale.ENGLISH);
MediaType mediaType = this.mediaTypes.get(extension);
if (mediaType == null) {
String mimeType = getServletContext().getMimeType(filename);
if (StringUtils.hasText(mimeType)) {
mediaType = MediaType.parseMediaType(mimeType);
}
if (this.useJaf
&& (mediaType == null || MediaType.APPLICATION_OCTET_STREAM.equals(mediaType))) {
MediaType jafMediaType = ActivationMediaTypeFactory.getMediaType(filename);
if (jafMediaType != null && !MediaType.APPLICATION_OCTET_STREAM.equals(jafMediaType)) {
mediaType = jafMediaType;
}
}
if (mediaType != null) {
this.mediaTypes.putIfAbsent(extension, mediaType);
}
}
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}.
* @since 4.3
*/
public MediaType getMediaTypeForResource(Resource resource) {
MediaType mediaType = super.getMediaTypeForResource(resource);
if (mediaType == null) {
String mimeType = this.servletContext.getMimeType(resource.getFilename());
if (StringUtils.hasText(mimeType)) {
mediaType = MediaType.parseMediaType(mimeType);
}
}
if (MediaType.APPLICATION_OCTET_STREAM.equals(mediaType)) {
mediaType = null;
}
return mediaType;
}
@Override
protected MediaType handleNoMatch(NativeWebRequest webRequest, String extension)
throws HttpMediaTypeNotAcceptableException {
if (this.useJaf && JAF_PRESENT) {
MediaType mediaType = JafMediaTypeFactory.getMediaType("file." + extension);
if (mediaType != null && !MediaType.APPLICATION_OCTET_STREAM.equals(mediaType)) {
return mediaType;
}
}
if (this.ignoreUnknownExtensions) {
return null;
}
throw new HttpMediaTypeNotAcceptableException(getAllMediaTypes());
}
/**
* A public method exposing the knowledge of the path extension strategy to resolve file
* extensions to a MediaType in this case for a given {@link Resource}. The method first looks up
* any explicitly registered file extensions first and then falls back on JAF if available.
*
* @param resource the resource to look up
* @return the MediaType for the extension or {@code null}.
* @since 4.3
*/
public MediaType getMediaTypeForResource(Resource resource) {
Assert.notNull(resource);
MediaType mediaType = null;
String filename = resource.getFilename();
String extension = StringUtils.getFilenameExtension(filename);
if (extension != null) {
mediaType = lookupMediaType(extension);
}
if (mediaType == null && JAF_PRESENT) {
mediaType = JafMediaTypeFactory.getMediaType(filename);
}
if (MediaType.APPLICATION_OCTET_STREAM.equals(mediaType)) {
mediaType = null;
}
return mediaType;
}
/**
* Resolve file extension via {@link ServletContext#getMimeType(String)} and also delegate to base
* class for a potential JAF lookup.
*/
@Override
protected MediaType handleNoMatch(NativeWebRequest webRequest, String extension)
throws HttpMediaTypeNotAcceptableException {
MediaType mediaType = null;
if (this.servletContext != 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;
}
/**
* Add default headers to the output message.
*
* <p>This implementation delegates to {@link #getDefaultContentType(Object)} if a content type
* was not provided, calls {@link #getContentLength}, and sets the corresponding headers
*
* @since 4.2
*/
protected void addDefaultHeaders(HttpHeaders headers, T t, MediaType contentType)
throws IOException {
if (headers.getContentType() == null) {
MediaType contentTypeToUse = contentType;
if (contentType == null || contentType.isWildcardType() || contentType.isWildcardSubtype()) {
contentTypeToUse = getDefaultContentType(t);
} else if (MediaType.APPLICATION_OCTET_STREAM.equals(contentType)) {
MediaType mediaType = getDefaultContentType(t);
contentTypeToUse = (mediaType != null ? mediaType : contentTypeToUse);
}
if (contentTypeToUse != null) {
headers.setContentType(contentTypeToUse);
}
}
if (headers.getContentLength() == -1) {
Long contentLength = getContentLength(t, headers.getContentType());
if (contentLength != null) {
headers.setContentLength(contentLength);
}
}
}
