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 */
017package org.apache.logging.log4j.core.config.plugins.validation.validators;
018
019import java.util.Collection;
020import java.util.Map;
021
022import org.apache.logging.log4j.Logger;
023import org.apache.logging.log4j.core.config.plugins.validation.ConstraintValidator;
024import org.apache.logging.log4j.core.config.plugins.validation.constraints.Required;
025import 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 */
039public 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}