/**
* Resolves a reference to a local or remote file or element. If the link refers to an element in
* the current document, this method returns that element. If the link refers to a remote
* document, this method will initiate asynchronous retrieval of the document, and return a URL of
* the downloaded document in the file cache, if it is available locally. If the link identifies a
* COLLADA document, the document will be returned as a parsed ColladaRoot.
*
* @param link the address of the document or element to resolve. This may be a full URL, a URL
* fragment that identifies an element in the current document ("#myElement"), or a URL and a
* fragment identifier ("http://server.com/model.dae#myElement").
* @return the requested element, or null if the element is not found.
* @throws IllegalArgumentException if the address is null.
*/
public Object resolveReference(String link) {
if (link == null) {
String message = Logging.getMessage("nullValue.DocumentSourceIsNull");
Logging.logger().severe(message);
throw new IllegalArgumentException(message);
}
try {
String[] linkParts = link.split("#");
String linkBase = linkParts[0];
String linkRef = linkParts.length > 1 ? linkParts[1] : null;
// See if it's a reference to an internal element.
if (WWUtil.isEmpty(linkBase) && !WWUtil.isEmpty(linkRef)) return this.getItemByID(linkRef);
// Interpret the path relative to the current document.
String path = this.getSupportFilePath(linkBase);
if (path == null) path = linkBase;
// See if it's an already found and parsed COLLADA file.
Object o = WorldWind.getSessionCache().get(path);
if (o != null && o instanceof ColladaRoot)
return linkRef != null ? ((ColladaRoot) o).getItemByID(linkRef) : o;
URL url = WWIO.makeURL(path);
if (url == null) {
// See if the reference can be resolved to a local file.
o = this.resolveLocalReference(path, linkRef);
}
// If we didn't find a local file, treat it as a remote reference.
if (o == null) o = this.resolveRemoteReference(path, linkRef);
if (o != null) return o;
// If the reference was not resolved as a remote reference, look for a local element
// identified by the
// reference string. This handles the case of malformed internal references that omit the #
// sign at the
// beginning of the reference.
return this.getItemByID(link);
} catch (Exception e) {
String message = Logging.getMessage("generic.UnableToResolveReference", link);
Logging.logger().warning(message);
}
return null;
}
/**
* Resolves a reference to a remote element identified by address and identifier, where {@code
* linkBase} identifies a remote document, and {@code linkRef} is the id of the desired element.
* This method retrieves resources asynchronously using the {@link
* gov.nasa.worldwind.cache.FileStore}.
*
* <p>The return value is null if the file is not yet available in the FileStore. If {@code
* linkBase} refers to a COLLADA file and {@code linkRef} is non-null, the return value is the
* element identified by {@code linkRef}. If {@code linkBase} refers to a COLLADA file and {@code
* linkRef} is null, the return value is a parsed {@link ColladaRoot} for the COLLADA file
* identified by {@code linkBase}. Otherwise the return value is a {@link URL} to the file in the
* file cache.
*
* @param linkBase the address of the document containing the requested element.
* @param linkRef the element's identifier.
* @return URL to the requested file, parsed ColladaRoot, or COLLADA element. Returns null if the
* document is not yet available in the FileStore.
* @throws IllegalArgumentException if the {@code linkBase} is null.
*/
public Object resolveRemoteReference(String linkBase, String linkRef) {
if (linkBase == null) {
String message = Logging.getMessage("nullValue.DocumentSourceIsNull");
Logging.logger().severe(message);
throw new IllegalArgumentException(message);
}
try {
// See if it's in the cache. If not, requestFile will start another thread to retrieve it and
// return null.
URL url = WorldWind.getDataFileStore().requestFile(linkBase);
if (url == null) return null;
// It's in the cache. If it's a COLLADA file try to parse it so we can search for the
// specified reference.
// If it's not COLLADA, just return the url for the cached file.
String contentType = WorldWind.getDataFileStore().getContentType(linkBase);
if (contentType == null) {
String suffix = WWIO.getSuffix(linkBase.split(";")[0]); // strip of trailing garbage
if (!WWUtil.isEmpty(suffix)) contentType = WWIO.makeMimeTypeForSuffix(suffix);
}
if (!this.canParseContentType(contentType)) return url;
// If the file is a COLLADA document, attempt to open it. We can't open it as a File with
// createAndParse
// because the ColladaRoot that will be created needs to have the remote address in order to
// resolve any
// relative references within it.
ColladaRoot refRoot = this.parseCachedColladaFile(url, linkBase);
// Add the parsed file to the session cache so it doesn't have to be parsed again.
WorldWind.getSessionCache().put(linkBase, refRoot);
// Now check the newly opened COLLADA file for the referenced item, if a reference was
// specified.
if (linkRef != null) return refRoot.getItemByID(linkRef);
else return refRoot;
} catch (Exception e) {
String message =
Logging.getMessage("generic.UnableToResolveReference", linkBase + "/" + linkRef);
Logging.logger().warning(message);
return null;
}
}
