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/appender/db/jdbc/FactoryMethodConnectionSource.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.appender.db.jdbc;

import java.io.PrintWriter;
import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.SQLException;
import javax.sql.DataSource;

import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.Core;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginFactory;
import org.apache.logging.log4j.core.util.Loader;
import org.apache.logging.log4j.status.StatusLogger;
import org.apache.logging.log4j.util.Strings;

/**
 * A {@link JdbcAppender} connection source that uses a public static factory method to obtain a {@link Connection} or
 * {@link DataSource}.
 */
@Plugin(name = "ConnectionFactory", category = Core.CATEGORY_NAME, elementType = "connectionSource", printObject = true)
public final class FactoryMethodConnectionSource extends AbstractConnectionSource {
    private static final Logger LOGGER = StatusLogger.getLogger();

    private final DataSource dataSource;
    private final String description;

    private FactoryMethodConnectionSource(final DataSource dataSource, final String className, final String methodName,
                                          final String returnType) {
        this.dataSource = dataSource;
        this.description = "factory{ public static " + returnType + ' ' + className + '.' + methodName + "() }";
    }

    @Override
    public Connection getConnection() throws SQLException {
        return this.dataSource.getConnection();
    }

    @Override
    public String toString() {
        return this.description;
    }

    /**
     * Factory method for creating a connection source within the plugin manager.
     *
     * @param className The name of a public class that contains a static method capable of returning either a
     *                  {@link DataSource} or a {@link Connection}.
     * @param methodName The name of the public static method on the aforementioned class that returns the data source
     *                   or connection. If this method returns a {@link Connection}, it should return a new connection
     *                   every call.
     * @return the created connection source.
     */
    @PluginFactory
    public static FactoryMethodConnectionSource createConnectionSource(
            @PluginAttribute("class") final String className,
            @PluginAttribute("method") final String methodName) {
        if (Strings.isEmpty(className) || Strings.isEmpty(methodName)) {
            LOGGER.error("No class name or method name specified for the connection factory method.");
            return null;
        }

        final Method method;
        try {
            final Class<?> factoryClass = Loader.loadClass(className);
            method = factoryClass.getMethod(methodName);
        } catch (final Exception e) {
            LOGGER.error(e.toString(), e);
            return null;
        }

        final Class<?> returnType = method.getReturnType();
        String returnTypeString = returnType.getName();
        DataSource dataSource;
        if (returnType == DataSource.class) {
            try {
                dataSource = (DataSource) method.invoke(null);
                returnTypeString += "[" + dataSource + ']';
            } catch (final Exception e) {
                LOGGER.error(e.toString(), e);
                return null;
            }
        } else if (returnType == Connection.class) {
            dataSource = new DataSource() {
                @Override
                public Connection getConnection() throws SQLException {
                    try {
                        return (Connection) method.invoke(null);
                    } catch (final Exception e) {
                        throw new SQLException("Failed to obtain connection from factory method.", e);
                    }
                }

                @Override
                public Connection getConnection(final String username, final String password) throws SQLException {
                    throw new UnsupportedOperationException();
                }

                @Override
                public int getLoginTimeout() throws SQLException {
                    throw new UnsupportedOperationException();
                }

                @Override
                public PrintWriter getLogWriter() throws SQLException {
                    throw new UnsupportedOperationException();
                }

                @Override
                @SuppressWarnings("unused")
                public java.util.logging.Logger getParentLogger() {
                    throw new UnsupportedOperationException();
                }

                @Override
                public boolean isWrapperFor(final Class<?> iface) throws SQLException {
                    return false;
                }

                @Override
                public void setLoginTimeout(final int seconds) throws SQLException {
                    throw new UnsupportedOperationException();
                }

                @Override
                public void setLogWriter(final PrintWriter out) throws SQLException {
                    throw new UnsupportedOperationException();
                }

                @Override
                public <T> T unwrap(final Class<T> iface) throws SQLException {
                    return null;
                }
            };
        } else {
            LOGGER.error("Method [{}.{}()] returns unsupported type [{}].", className, methodName,
                    returnType.getName());
            return null;
        }

        return new FactoryMethodConnectionSource(dataSource, className, methodName, returnTypeString);
    }
}

⏎ org/apache/logging/log4j/core/appender/db/jdbc/FactoryMethodConnectionSource.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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