org.apache.tika.detect.CompositeDetector Maven / Gradle / Ivy
/*
* 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.tika.detect;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import org.apache.tika.metadata.Metadata;
import org.apache.tika.metadata.TikaCoreProperties;
import org.apache.tika.mime.MediaType;
import org.apache.tika.mime.MediaTypeRegistry;
/**
* Content type detector that combines multiple different detection mechanisms.
*/
public class CompositeDetector implements Detector {
/**
* Serial version UID
*/
private static final long serialVersionUID = 5980683158436430252L;
private final MediaTypeRegistry registry;
private final List detectors;
public CompositeDetector(MediaTypeRegistry registry,
List detectors, Collection> excludeDetectors) {
if (excludeDetectors == null || excludeDetectors.isEmpty()) {
this.detectors = detectors;
} else {
this.detectors = new ArrayList();
for (Detector d : detectors) {
if (!isExcluded(excludeDetectors, d.getClass())) {
this.detectors.add(d);
}
}
}
this.registry = registry;
}
public CompositeDetector(MediaTypeRegistry registry,
List detectors) {
this(registry, detectors, null);
}
public CompositeDetector(List detectors) {
this(new MediaTypeRegistry(), detectors);
}
public CompositeDetector(Detector... detectors) {
this(Arrays.asList(detectors));
}
public MediaType detect(InputStream input, Metadata metadata)
throws IOException {
MediaType type = MediaType.OCTET_STREAM;
for (Detector detector : getDetectors()) {
//short circuit via OverrideDetector
//can't rely on ordering because subsequent detector may
//change Override's to a specialization of Override's
if (detector instanceof OverrideDetector && metadata.get(TikaCoreProperties.CONTENT_TYPE_OVERRIDE) != null) {
return detector.detect(input, metadata);
}
MediaType detected = detector.detect(input, metadata);
if (registry.isSpecializationOf(detected, type)) {
type = detected;
}
}
return type;
}
/**
* Returns the component detectors.
*/
public List getDetectors() {
return Collections.unmodifiableList(detectors);
}
private boolean isExcluded(Collection> excludeDetectors, Class d) {
return excludeDetectors.contains(d) || assignableFrom(excludeDetectors, d);
}
private boolean assignableFrom(Collection> excludeDetectors, Class d) {
for (Class e : excludeDetectors) {
if (e.isAssignableFrom(d)) return true;
}
return false;
}
}