Apache Log4j Core Implementation provides the functional components of the logging system. Users are free to create their own plugins and include them in the logging configuration. Apache Log4j Core is a required module to use Apache Log4j.

Bytecode (Java 8) for Apache Log4j Core Implementation is provided in a separate JAR file like log4j-core-2.14.1.jar.

Source Code files for Apache Log4j API are provided in both binary packge like apache-log4j-2.14.1-bin.zip and source package like apache-log4j-2.14.1-src.zip. You can download them at Apache Log4j Website.

You can also browse Source Code files for Apache Log4j Core Implementation 2.14.1 below.

⏎ org/apache/logging/log4j/core/config/plugins/validation/ConstraintValidators.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.logging.log4j.core.config.plugins.validation;

import java.lang.annotation.Annotation;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Collection;

import org.apache.logging.log4j.core.util.ReflectionUtil;

/**
 * Utility class to locate an appropriate {@link ConstraintValidator} implementation for an annotation.
 *
 * @since 2.1
 */
public final class ConstraintValidators {

    private ConstraintValidators() {
    }

    /**
     * Finds all relevant {@link ConstraintValidator} objects from an array of annotations. All validators will be
     * {@link ConstraintValidator#initialize(java.lang.annotation.Annotation) initialized} before being returned.
     *
     * @param annotations the annotations to find constraint validators for
     * @return a collection of ConstraintValidators for the given annotations
     */
    public static Collection<ConstraintValidator<?>> findValidators(final Annotation... annotations) {
        final Collection<ConstraintValidator<?>> validators =
            new ArrayList<>();
        for (final Annotation annotation : annotations) {
            final Class<? extends Annotation> type = annotation.annotationType();
            if (type.isAnnotationPresent(Constraint.class)) {
                final ConstraintValidator<?> validator = getValidator(annotation, type);
                if (validator != null) {
                    validators.add(validator);
                }
            }
        }
        return validators;
    }

    private static <A extends Annotation> ConstraintValidator<A> getValidator(final A annotation,
                                                                              final Class<? extends A> type) {
        final Constraint constraint = type.getAnnotation(Constraint.class);
        final Class<? extends ConstraintValidator<?>> validatorClass = constraint.value();
        if (type.equals(getConstraintValidatorAnnotationType(validatorClass))) {
            @SuppressWarnings("unchecked") // I don't think we could be any more thorough in validation here
            final ConstraintValidator<A> validator = (ConstraintValidator<A>)
                ReflectionUtil.instantiate(validatorClass);
            validator.initialize(annotation);
            return validator;
        }
        return null;
    }

    private static Type getConstraintValidatorAnnotationType(final Class<? extends ConstraintValidator<?>> type) {
        for (final Type parentType : type.getGenericInterfaces()) {
            if (parentType instanceof ParameterizedType) {
                final ParameterizedType parameterizedType = (ParameterizedType) parentType;
                if (ConstraintValidator.class.equals(parameterizedType.getRawType())) {
                    return parameterizedType.getActualTypeArguments()[0];
                }
            }
        }
        return Void.TYPE;
    }
}

⏎ org/apache/logging/log4j/core/config/plugins/validation/ConstraintValidators.java

Or download all of them as a single archive file:

File name: log4j-core-2.14.1-sources.jar
File size: 1281358 bytes
Release date: 2021-03-06
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