Java tutorial
/** * Licensed to JumpMind Inc under one or more contributor * license agreements. See the NOTICE file distributed * with this work for additional information regarding * copyright ownership. JumpMind Inc licenses this file * to you under the GNU General Public License, version 3.0 (GPLv3) * (the "License"); you may not use this file except in compliance * with the License. * * You should have received a copy of the GNU General Public License, * version 3.0 (GPLv3) along with this library; if not, see * <http://www.gnu.org/licenses/>. * * 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.jumpmind.util; import java.util.ArrayList; import java.util.Collections; import java.util.LinkedHashMap; import java.util.List; import java.util.Map; import org.apache.commons.lang.StringUtils; import org.apache.log4j.AppenderSkeleton; import org.apache.log4j.spi.LoggingEvent; public class BufferedLogAppender extends AppenderSkeleton { protected Map<String, List<LoggingEvent>> events = Collections .synchronizedMap(new LinkedHashMap<String, List<LoggingEvent>>()); protected int size = 100; protected String filterText; @Override protected void append(LoggingEvent event) { Object mdc = event.getMDC("engineName"); boolean addEvent = mdc != null; if (addEvent && filterText != null) { String message = (String) event.getMessage(); addEvent = message.contains(filterText); addEvent |= event.getLoggerName().contains(filterText); if (mdc != null) { addEvent |= mdc.toString().contains(filterText); } } if (addEvent) { String engineName = mdc.toString(); List<LoggingEvent> list = events.get(engineName); if (list == null) { list = Collections.synchronizedList(new ArrayList<LoggingEvent>(size)); events.put(engineName, list); } list.add(event); if (list.size() > size) { list.remove(0); } } } public void close() { } public boolean requiresLayout() { return false; } public void setSize(int size) { this.size = size; while (events.size() > size) { events.remove(0); } } public int getSize() { return size; } public void setFilterText(String filterText) { if (StringUtils.isBlank(filterText)) { this.filterText = null; } else { this.filterText = filterText; } } public String getFilterText() { return filterText; } public List<LoggingEvent> getEvents(String engineName) { return events.get(engineName); } }