001: /* ====================================================================
002: * The Apache Software License, Version 1.1
003: *
004: * Copyright (c) 1997-2003 The Apache Software Foundation. All rights
005: * reserved.
006: *
007: * Redistribution and use in source and binary forms, with or without
008: * modification, are permitted provided that the following conditions
009: * are met:
010: *
011: * 1. Redistributions of source code must retain the above copyright
012: * notice, this list of conditions and the following disclaimer.
013: *
014: * 2. Redistributions in binary form must reproduce the above copyright
015: * notice, this list of conditions and the following disclaimer in
016: * the documentation and/or other materials provided with the
017: * distribution.
018: *
019: * 3. The end-user documentation included with the redistribution,
020: * if any, must include the following acknowledgment:
021: * "This product includes software developed by the
022: * Apache Software Foundation (http://www.apache.org/)."
023: * Alternately, this acknowledgment may appear in the software
024: * itself, if and wherever such third-party acknowledgments
025: * normally appear.
026: *
027: * 4. The names "Jakarta", "Avalon", and "Apache Software Foundation"
028: * must not be used to endorse or promote products derived from this
029: * software without prior written permission. For written
030: * permission, please contact apache@apache.org.
031: *
032: * 5. Products derived from this software may not be called "Apache",
033: * nor may "Apache" appear in their name, without prior written
034: * permission of the Apache Software Foundation.
035: *
036: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
037: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
038: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
039: * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
040: * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
041: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
042: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
043: * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
044: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
045: * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
046: * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
047: * SUCH DAMAGE.
048: * ====================================================================
049: *
050: * This software consists of voluntary contributions made by many
051: * individuals on behalf of the Apache Software Foundation. For more
052: * information on the Apache Software Foundation, please see
053: * <http://www.apache.org/>.
054: */
055: package org.apache.log.output.db;
056:
057: import java.sql.Connection;
058: import java.sql.SQLException;
059: import javax.sql.DataSource;
060: import org.apache.log.LogEvent;
061: import org.apache.log.output.AbstractTarget;
062:
063: /**
064: * Abstract JDBC target.
065: *
066: * @author <a href="mailto:dev@avalon.apache.org">Avalon Development Team</a>
067: * @author <a href="mailto:peter@apache.org">Peter Donald</a>
068: */
069: public abstract class AbstractJDBCTarget extends AbstractTarget {
070: ///Datasource to extract connections from
071: private DataSource m_dataSource;
072:
073: ///Database connection
074: private Connection m_connection;
075:
076: /**
077: * Creation of a new instance of the AbstractJDBCTarget.
078: * @param dataSource the JDBC datasource
079: */
080: protected AbstractJDBCTarget(final DataSource dataSource) {
081: m_dataSource = dataSource;
082: }
083:
084: /**
085: * Process a log event, via formatting and outputting it.
086: *
087: * @param event the log event
088: * @exception Exception if an event processing error occurs
089: */
090: protected synchronized void doProcessEvent(final LogEvent event)
091: throws Exception {
092: checkConnection();
093:
094: if (isOpen()) {
095: output(event);
096: }
097: }
098:
099: /**
100: * Output a log event to DB.
101: * This must be implemented by subclasses.
102: *
103: * @param event the log event.
104: */
105: protected abstract void output(LogEvent event);
106:
107: /**
108: * Startup log session.
109: *
110: */
111: protected synchronized void open() {
112: if (!isOpen()) {
113: super .open();
114: openConnection();
115: }
116: }
117:
118: /**
119: * Open connection to underlying database.
120: *
121: */
122: protected synchronized void openConnection() {
123: try {
124: m_connection = m_dataSource.getConnection();
125: } catch (final Throwable throwable) {
126: getErrorHandler().error("Unable to open connection",
127: throwable, null);
128: }
129: }
130:
131: /**
132: * Utility method for subclasses to access connection.
133: *
134: * @return the Connection
135: */
136: protected final synchronized Connection getConnection() {
137: return m_connection;
138: }
139:
140: /**
141: * Utility method to check connection and bring it back up if necessary.
142: */
143: protected final synchronized void checkConnection() {
144: if (isStale()) {
145: closeConnection();
146: openConnection();
147: }
148: }
149:
150: /**
151: * Detect if connection is stale and should be reopened.
152: *
153: * @return true if connection is stale, false otherwise
154: */
155: protected synchronized boolean isStale() {
156: if (null == m_connection) {
157: return true;
158: }
159:
160: try {
161: if (m_connection.isClosed()) {
162: return true;
163: }
164: } catch (final SQLException se) {
165: return true;
166: }
167:
168: return false;
169: }
170:
171: /**
172: * Shutdown target.
173: * Attempting to write to target after close() will cause errors to be logged.
174: *
175: */
176: public synchronized void close() {
177: if (isOpen()) {
178: closeConnection();
179: super .close();
180: }
181: }
182:
183: /**
184: * Close connection to underlying database.
185: *
186: */
187: protected synchronized void closeConnection() {
188: if (null != m_connection) {
189: try {
190: m_connection.close();
191: } catch (final SQLException se) {
192: getErrorHandler()
193: .error("Error shutting down JDBC connection",
194: se, null);
195: }
196:
197: m_connection = null;
198: }
199: }
200: }
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