    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.web.appender;
    018
    019    import java.io.Serializable;
    020    import javax.servlet.ServletContext;
    021
    022    import org.apache.logging.log4j.core.Filter;
    023    import org.apache.logging.log4j.core.Layout;
    024    import org.apache.logging.log4j.core.LogEvent;
    025    import org.apache.logging.log4j.core.appender.AbstractAppender;
    026    import org.apache.logging.log4j.core.config.plugins.Plugin;
    027    import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
    028    import org.apache.logging.log4j.core.config.plugins.PluginElement;
    029    import org.apache.logging.log4j.core.config.plugins.PluginFactory;
    030    import org.apache.logging.log4j.core.config.plugins.validation.constraints.Required;
    031    import org.apache.logging.log4j.core.layout.AbstractStringLayout;
    032    import org.apache.logging.log4j.core.layout.PatternLayout;
    033    import org.apache.logging.log4j.web.WebLoggerContextUtils;
    034
    035    /**
    036     * Logs using the ServletContext's log method
    037     */
    038    @Plugin(name = "Servlet", category = "Core", elementType = "appender", printObject = true)
    039    public class ServletAppender extends AbstractAppender {
    040
    041        private static final long serialVersionUID = 1L;
    042
    043        private final ServletContext servletContext;
    044
    045        private ServletAppender(final String name, final AbstractStringLayout layout, final Filter filter,
    046                                final ServletContext servletContext, final boolean ignoreExceptions) {
    047            super(name, filter, layout, ignoreExceptions);
    048            this.servletContext = servletContext;
    049        }
    050
    051        @Override
    052        public void append(final LogEvent event) {
    053            servletContext.log(((AbstractStringLayout) getLayout()).toSerializable(event));
    054        }
    055
    056        /**
    057         * Create a Servlet Appender.
    058         * @param layout The layout to use (required). Must extend {@link AbstractStringLayout}.
    059         * @param filter The Filter or null.
    060         * @param name The name of the Appender (required).
    061         * @param ignoreExceptions If {@code true} (default) exceptions encountered when appending events are logged;
    062         *                         otherwise they are propagated to the caller.
    063         * @return The ServletAppender.
    064         */
    065        @PluginFactory
    066        public static ServletAppender createAppender(
    067                @PluginElement("Layout") Layout<? extends Serializable> layout,
    068                @PluginElement("Filter") final Filter filter,
    069                @PluginAttribute("name")
    070                @Required(message = "No name provided for ServletAppender")
    071                final String name,
    072                @PluginAttribute(value = "ignoreExceptions", defaultBoolean = true) final boolean ignoreExceptions) {
    073            final ServletContext servletContext = WebLoggerContextUtils.getServletContext();
    074            if (servletContext == null) {
    075                LOGGER.error("No servlet context is available");
    076                return null;
    077            }
    078            if (layout == null) {
    079                layout = PatternLayout.createDefaultLayout();
    080            } else if (!(layout instanceof AbstractStringLayout)) {
    081                LOGGER.error("Layout must be a StringLayout to log to ServletContext");
    082                return null;
    083            }
    084            return new ServletAppender(name, (AbstractStringLayout) layout, filter, servletContext, ignoreExceptions);
    085        }
    086
    087    }