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.web.appender;
018
019import java.io.Serializable;
020import javax.servlet.ServletContext;
021
022import org.apache.logging.log4j.core.Filter;
023import org.apache.logging.log4j.core.Layout;
024import org.apache.logging.log4j.core.LogEvent;
025import org.apache.logging.log4j.core.appender.AbstractAppender;
026import org.apache.logging.log4j.core.config.plugins.Plugin;
027import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
028import org.apache.logging.log4j.core.config.plugins.PluginElement;
029import org.apache.logging.log4j.core.config.plugins.PluginFactory;
030import org.apache.logging.log4j.core.config.plugins.validation.constraints.Required;
031import org.apache.logging.log4j.core.layout.AbstractStringLayout;
032import org.apache.logging.log4j.core.layout.PatternLayout;
033import 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)
039public 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}