Java tutorial
/* * Copyright (C) 2010 Robert Stewart (robert@wombatnation.com) * * Licensed 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.log4mongo; import com.mongodb.DBObject; import com.mongodb.MongoException; import com.mongodb.util.JSON; import org.apache.log4j.spi.ErrorCode; import org.apache.log4j.spi.LoggingEvent; import org.bson.Document; /** * A Log4J Appender that uses a PatternLayout to write log events into a MongoDB database. * <p> * The conversion pattern specifies the format of a JSON document. The document can contain * sub-documents and the elements can be strings or arrays. * <p> * For some Log4J appenders (especially file appenders) blank space padding is often used to get * fields in adjacent rows to line up. For example, %-5p is often used to make all log levels the * same width in characters. Since each value is stored in a separate property in the document, it * usually doesn't make sense to use blank space padding with MongoDbPatternLayoutAppender. * <p> * The appender does <u>not</u> create any indexes on the data that's stored. If query performance * is required, indexes must be created externally (e.g., in the mongo shell or an external * reporting application). * * @author Robert Stewart (robert@wombatnation.com) * @see <a href="http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/Appender.html">Log4J * Appender Interface</a> * @see <a href="http://www.mongodb.org/">MongoDB</a> */ public class MongoDbPatternLayoutAppender extends MongoDbAppender { @Override public boolean requiresLayout() { return (true); } /** * Inserts a BSON representation of a LoggingEvent into a MongoDB collection. A PatternLayout is * used to format a JSON document containing data available in the LoggingEvent and, optionally, * additional data returned by custom PatternConverters. * <p> * The format of the JSON document is specified in the .layout.ConversionPattern property. * * @param loggingEvent * The LoggingEvent that will be formatted and stored in MongoDB */ @Override protected void append(final LoggingEvent loggingEvent) { if (isInitialized()) { DBObject bson = null; String json = layout.format(loggingEvent); if (json.length() > 0) { Object obj = JSON.parse(json); if (obj instanceof DBObject) { bson = (DBObject) obj; } } if (bson != null) { try { getCollection().insertOne(new Document(bson.toMap())); } catch (MongoException e) { errorHandler.error("Failed to insert document to MongoDB", e, ErrorCode.WRITE_FAILURE); } } } } }