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This is the core Apache Tika™ toolkit library from which all other modules inherit functionality. It also includes the core facades for the Tika API.
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/*
 * 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.utils;

import org.apache.tika.config.Field;
import org.apache.tika.config.Param;
import org.apache.tika.config.ParamField;
import org.apache.tika.config.TikaConfig;
import org.apache.tika.exception.TikaConfigException;

import java.lang.annotation.Annotation;
import java.lang.reflect.AccessibleObject;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Set;

/**
 * This class contains utilities for dealing with tika annotations
 * @since Apache Tika 1.14
 */
public class AnnotationUtils {

    /**
     * Cache for annotations for Bean classes which have {@link Field}
     */
    private static final Map, List> PARAM_INFO =
            new HashMap<>();

    /**
     * Collects all the fields and methods for an annotation
     * @param clazz bean class with annotations
     * @param annotation annotation class
     * @return list of accessible objects such as fields and methods
     */
    private static List collectInfo(
            Class clazz, Class annotation) {

        Class superClazz = clazz;
        List members = new ArrayList<>();
        List annotatedMembers = new ArrayList<>();
        //walk through the inheritance chain
        while (superClazz != null && superClazz != Object.class) {
            members.addAll(Arrays.asList(superClazz.getDeclaredFields()));
            members.addAll(Arrays.asList(superClazz.getDeclaredMethods()));
            superClazz = superClazz.getSuperclass();
        }

        for (final AccessibleObject member : members) {
            if (member.isAnnotationPresent(annotation)) {
                AccessController.doPrivileged(new PrivilegedAction(){
                    @Override
                    public Void run() {
                        member.setAccessible(true);
                        return null;
                    }
                });
                annotatedMembers.add(member);
            }
        }
        return annotatedMembers;
    }

    /**
     * Assigns the param values to bean
     * @throws TikaConfigException when an error occurs while assigning params
     */
    public static void assignFieldParams(Object bean, Map params) throws TikaConfigException {
        Class beanClass = bean.getClass();
        if (!PARAM_INFO.containsKey(beanClass)) {
            synchronized (TikaConfig.class){
                if (!PARAM_INFO.containsKey(beanClass)) {
                    List aObjs = collectInfo(beanClass,
                            org.apache.tika.config.Field.class);
                    List fields = new ArrayList<>(aObjs.size());

                    for (AccessibleObject aObj : aObjs) {
                        fields.add(new ParamField(aObj));
                    }
                    PARAM_INFO.put(beanClass, fields);
                }
            }
        }

        List fields = PARAM_INFO.get(beanClass);

        Set validFieldNames = new HashSet<>();

        for (ParamField field : fields) {
            validFieldNames.add(field.getName());
            Param param = params.get(field.getName());
            if (param != null){
                if (field.getType().isAssignableFrom(param.getType())) {
                    try {
                        field.assignValue(bean, param.getValue());
                    } catch (Exception e) {
                        throw new TikaConfigException(e.getMessage(), e);
                    }
                } else {
                    String msg = String.format(Locale.ROOT, "Value '%s' of type '%s' cant be" +
                            " assigned to field '%s' of defined type '%s'",
                            param.getValue(), param.getValue().getClass(),
                            field.getName(), field.getType());
                    throw new TikaConfigException(msg);
                }
            } else if (field.isRequired()){
                //param not supplied but field is declared as required?
                String msg = String.format(Locale.ROOT, "Param %s is required for %s," +
                        " but it is not given in config.", field.getName(),
                        bean.getClass().getName());
                throw new TikaConfigException(msg);
            } else {
                //FIXME: SLF4j is not showing up for import, fix it and send this to LOG.debug
                //LOG.debug("Param not supplied, field is not mandatory");
            }
        }
    }
}