    001    /*
    002     * Licensed to the Apache Software Foundation (ASF) under one or more
    003     * contributor license agreements. See the NOTICE file distributed with
    004     * this work for additional information regarding copyright ownership.
    005     * The ASF licenses this file to You under the Apache license, Version 2.0
    006     * (the "License"); you may not use this file except in compliance with
    007     * the License. You may obtain a copy of the License at
    008     *
    009     *      http://www.apache.org/licenses/LICENSE-2.0
    010     *
    011     * Unless required by applicable law or agreed to in writing, software
    012     * distributed under the License is distributed on an "AS IS" BASIS,
    013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014     * See the license for the specific language governing permissions and
    015     * limitations under the license.
    016     */
    017    package org.apache.logging.log4j.core.config.plugins.validation.validators;
    018
    019    import java.util.Collection;
    020    import java.util.Map;
    021
    022    import org.apache.logging.log4j.Logger;
    023    import org.apache.logging.log4j.core.config.plugins.validation.ConstraintValidator;
    024    import org.apache.logging.log4j.core.config.plugins.validation.constraints.Required;
    025    import org.apache.logging.log4j.status.StatusLogger;
    026
    027    /**
    028     * Validator that checks an object for emptiness. Emptiness is defined here as:
    029     * <ul>
    030     * <li>The value {@code null}</li>
    031     * <li>An object of type {@link CharSequence} with length 0</li>
    032     * <li>An empty array</li>
    033     * <li>An empty {@link Collection}</li>
    034     * <li>An empty {@link Map}</li>
    035     * </ul>
    036     *
    037     * @since 2.1
    038     */
    039    public class RequiredValidator implements ConstraintValidator<Required> {
    040
    041        private static final Logger LOGGER = StatusLogger.getLogger();
    042
    043        private Required annotation;
    044
    045        @Override
    046        public void initialize(final Required annotation) {
    047            this.annotation = annotation;
    048        }
    049
    050        @Override
    051        public boolean isValid(final Object value) {
    052            if (value == null) {
    053                return err();
    054            }
    055            if (value instanceof CharSequence) {
    056                final CharSequence sequence = (CharSequence) value;
    057                return sequence.length() != 0 || err();
    058            }
    059            final Class<?> clazz = value.getClass();
    060            if (clazz.isArray()) {
    061                final Object[] array = (Object[]) value;
    062                return array.length != 0 || err();
    063            }
    064            if (Collection.class.isAssignableFrom(clazz)) {
    065                final Collection<?> collection = (Collection<?>) value;
    066                return collection.size() != 0 || err();
    067            }
    068            if (Map.class.isAssignableFrom(clazz)) {
    069                final Map<?, ?> map = (Map<?, ?>) value;
    070                return map.size() != 0 || err();
    071            }
    072            LOGGER.debug("Encountered type [{}] which can only be checked for null.", clazz.getName());
    073            return true;
    074        }
    075
    076        private boolean err() {
    077            LOGGER.error(annotation.message());
    078            return false;
    079        }
    080    }