MimeTypeProvider.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.sling.commons.mime;

import org.osgi.annotation.versioning.ConsumerType;

/**
 * The <code>MimeTypeProvider</code> interface defines an API for services
 * which are asked for MIME type mappings for unknown MIME types or extensions.
 * <p>
 * It is important to understand, that services registered with this interface
 * are only called as a last resort and that the first service asked and
 * replying with a non-<code>null</code> answer wins. Specifically if a MIME
 * type mapping is configured by default or as an extension to the MIME type
 * service, MimeTypeProvider services are not queried.
 * <p>
 * This interface may be implemented by bundles wishing to provide control over
 * how extensions are mapped to MIME types and vice-versa.
 */
@ConsumerType
public interface MimeTypeProvider {

    /**
     * Returns the MIME type of the extension of the given <code>name</code>.
     * The extension is the part of the name after the last dot. If the name
     * does not contain a dot, the name as a whole is assumed to be the
     * extension.
     *
     * @param name The name for which the MIME type is to be returned.
     * @return The MIME type for the extension of the name. If the extension
     *         cannot be mapped to a MIME type or <code>name</code> is
     *         <code>null</code>, <code>null</code> is returned.
     * @see #getExtension(String)
     */
    String getMimeType(String name);

    /**
     * Returns the primary name extension to which the given
     * <code>mimeType</code> maps. The returned extension must map to the
     * given <code>mimeType</code> when fed to the
     * {@link #getMimeType(String)} method. In other words, the expression
     * <code>mimeType.equals(getMimeType(getExtension(mimeType)))</code> must
     * always be <code>true</code> for any non-<code>null</code> MIME type.
     * <p>
     * A MIME type may be mapped to multiple extensions (e.g.
     * <code>text/plain</code> to <code>txt</code>, <code>log</code>,
     * ...). This method is expected to returned one of those extensions. It is
     * up to the implementation to select an appropriate extension if multiple
     * mappings exist for a single MIME type.
     *
     * @param mimeType The MIME type whose primary extension is requested.
     * @return A extension which maps to the given MIME type or
     *         <code>null</code> if no such mapping exists.
     * @see #getMimeType(String)
     */
    String getExtension(String mimeType);

}