Apache Log4j 1.2 Bridge allows applications coded to use Log4j 1.2 API to use Log4j 2 instead.

Bytecode (Java 8) for Apache Log4j 1.2 Bridge is provided in a separate JAR file like log4j-1.2-api-2.14.1.jar.

Source Code files for Apache Log4j 1.2 Bridge 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 1.2 Bridge 2.14.1 below.

⏎ org/apache/log4j/builders/appender/AsyncAppenderBuilder.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.log4j.builders.appender;

import org.apache.log4j.Appender;
import org.apache.log4j.bridge.AppenderWrapper;
import org.apache.log4j.builders.AbstractBuilder;
import org.apache.log4j.builders.BooleanHolder;
import org.apache.log4j.builders.Holder;
import org.apache.log4j.config.Log4j1Configuration;
import org.apache.log4j.config.PropertiesConfiguration;
import org.apache.log4j.helpers.OptionConverter;
import org.apache.log4j.xml.XmlConfiguration;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.appender.AsyncAppender;
import org.apache.logging.log4j.core.config.AppenderRef;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.status.StatusLogger;
import org.w3c.dom.Element;

import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

import static org.apache.log4j.builders.BuilderManager.CATEGORY;
import static org.apache.log4j.xml.XmlConfiguration.NAME_ATTR;
import static org.apache.log4j.xml.XmlConfiguration.PARAM_TAG;
import static org.apache.log4j.xml.XmlConfiguration.VALUE_ATTR;
import static org.apache.log4j.xml.XmlConfiguration.forEachElement;
import static org.apache.log4j.config.Log4j1Configuration.APPENDER_REF_TAG;
import static org.apache.log4j.config.Log4j1Configuration.THRESHOLD_PARAM;


/**
 * Build an Asynch Appender
 */
@Plugin(name = "org.apache.log4j.AsyncAppender", category = CATEGORY)
public class AsyncAppenderBuilder extends AbstractBuilder implements AppenderBuilder {

    private static final Logger LOGGER = StatusLogger.getLogger();
    private static final String BLOCKING_PARAM = "Blocking";
    private static final String INCLUDE_LOCATION_PARAM = "IncludeLocation";

    public AsyncAppenderBuilder() {
    }

    public AsyncAppenderBuilder(String prefix, Properties props) {
        super(prefix, props);
    }

    @Override
    public Appender parseAppender(final Element appenderElement, final XmlConfiguration config) {
        String name = appenderElement.getAttribute(NAME_ATTR);
        Holder<List<String>> appenderRefs = new Holder<>(new ArrayList<>());
        Holder<Boolean> blocking = new BooleanHolder();
        Holder<Boolean> includeLocation = new BooleanHolder();
        Holder<String> level = new Holder<>("trace");
        Holder<Integer> bufferSize = new Holder<>(1024);
        forEachElement(appenderElement.getChildNodes(), currentElement -> {
            switch (currentElement.getTagName()) {
                case APPENDER_REF_TAG:
                    Appender appender = config.findAppenderByReference(currentElement);
                    if (appender != null) {
                        appenderRefs.get().add(appender.getName());
                    }
                    break;
                case PARAM_TAG: {
                    switch (currentElement.getAttribute(NAME_ATTR)) {
                        case BUFFER_SIZE_PARAM: {
                            String value = currentElement.getAttribute(VALUE_ATTR);
                            if (value == null) {
                                LOGGER.warn("No value supplied for BufferSize parameter. Defaulting to 1024.");
                            } else {
                                bufferSize.set(Integer.parseInt(value));
                            }
                            break;
                        }
                        case BLOCKING_PARAM: {
                            String value = currentElement.getAttribute(VALUE_ATTR);
                            if (value == null) {
                                LOGGER.warn("No value supplied for Blocking parameter. Defaulting to false.");
                            } else {
                                blocking.set(Boolean.parseBoolean(value));
                            }
                            break;
                        }
                        case INCLUDE_LOCATION_PARAM: {
                            String value = currentElement.getAttribute(VALUE_ATTR);
                            if (value == null) {
                                LOGGER.warn("No value supplied for IncludeLocation parameter. Defaulting to false.");
                            } else {
                                includeLocation.set(Boolean.parseBoolean(value));
                            }
                            break;
                        }
                        case THRESHOLD_PARAM: {
                            String value = currentElement.getAttribute(VALUE_ATTR);
                            if (value == null) {
                                LOGGER.warn("No value supplied for Threshold parameter, ignoring.");
                            } else {
                                level.set(value);
                            }
                            break;
                        }
                    }
                    break;
                }
            }
        });
        return createAppender(name, level.get(), appenderRefs.get().toArray(new String[0]), blocking.get(),
                bufferSize.get(), includeLocation.get(), config);
    }

    @Override
    public Appender parseAppender(final String name, final String appenderPrefix, final String layoutPrefix,
            final String filterPrefix, final Properties props, final PropertiesConfiguration configuration) {
        String appenderRef = getProperty(APPENDER_REF_TAG);
        boolean blocking = getBooleanProperty(BLOCKING_PARAM);
        boolean includeLocation = getBooleanProperty(INCLUDE_LOCATION_PARAM);
        String level = getProperty(THRESHOLD_PARAM);
        int bufferSize = getIntegerProperty(BUFFER_SIZE_PARAM, 1024);
        if (appenderRef == null) {
            LOGGER.warn("No appender references configured for AsyncAppender {}", name);
            return null;
        }
        Appender appender = configuration.parseAppender(props, appenderRef);
        if (appender == null) {
            LOGGER.warn("Cannot locate Appender {}", appenderRef);
            return null;
        }
        return createAppender(name, level, new String[] {appenderRef}, blocking, bufferSize, includeLocation,
                configuration);
    }

    private <T extends Log4j1Configuration> Appender createAppender(String name, String level,
            String[] appenderRefs, boolean blocking, int bufferSize, boolean includeLocation,
            T configuration) {
        org.apache.logging.log4j.Level logLevel = OptionConverter.convertLevel(level,
                org.apache.logging.log4j.Level.TRACE);
        AppenderRef[] refs = new AppenderRef[appenderRefs.length];
        int index = 0;
        for (String appenderRef : appenderRefs) {
            refs[index++] = AppenderRef.createAppenderRef(appenderRef, logLevel, null);
        }
        return new AppenderWrapper(AsyncAppender.newBuilder()
                .setName(name)
                .setAppenderRefs(refs)
                .setBlocking(blocking)
                .setBufferSize(bufferSize)
                .setIncludeLocation(includeLocation)
                .setConfiguration(configuration)
                .build());
    }
}

⏎ org/apache/log4j/builders/appender/AsyncAppenderBuilder.java

Or download all of them as a single archive file:

File name: log4j-1.2-api-2.14.1-sources.jar
File size: 168047 bytes
Release date: 2021-03-06
Download 

⇒ Source Code for Apache Log4j JMX GUI

⇐ Source Code for Apache Log4j Flume Appender

⇑ Downloading and Reviewing Apache Log4j Packages

⇑⇑ FAQ for Apache Log4j