/*
* Copyright 1999-2005 The Apache Software Foundation.
*
* 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.apache.log4j.jdbc;
import org.apache.log4j.*;
import org.apache.log4j.spi.*;
import org.apache.log4j.PatternLayout;
import java.util.ArrayList;
import java.util.Iterator;
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.Statement;
import java.sql.SQLException;
/**
<p><b><font color="#FF2222">WARNING: This version of JDBCAppender
is very likely to be completely replaced in the future. Moreoever,
it does not log exceptions</font></b>.
The JDBCAppender provides for sending log events to a database.
<p>Each append call adds to an <code>ArrayList</code> buffer. When
the buffer is filled each log event is placed in a sql statement
(configurable) and executed.
<b>BufferSize</b>, <b>db URL</b>, <b>User</b>, & <b>Password</b> are
configurable options in the standard log4j ways.
<p>The <code>setSql(String sql)</code> sets the SQL statement to be
used for logging -- this statement is sent to a
<code>PatternLayout</code> (either created automaticly by the
appender or added by the user). Therefore by default all the
conversion patterns in <code>PatternLayout</code> can be used
inside of the statement. (see the test cases for examples)
<p>Overriding the {@link #getLogStatement} method allows more
explicit control of the statement used for logging.
<p>For use as a base class:
<ul>
<li>Override <code>getConnection()</code> to pass any connection
you want. Typically this is used to enable application wide
connection pooling.
<li>Override <code>closeConnection(Connection con)</code> -- if
you override getConnection make sure to implement
<code>closeConnection</code> to handle the connection you
generated. Typically this would return the connection to the
pool it came from.
<li>Override <code>getLogStatement(LoggingEvent event)</code> to
produce specialized or dynamic statements. The default uses the
sql option value.
</ul>
@author Kevin Steppe (<A HREF="mailto:ksteppe@pacbell.net">ksteppe@pacbell.net</A>)
*/
public class JDBCAppender extends org.apache.log4j.AppenderSkeleton
implements org.apache.log4j.Appender {
/**
* URL of the DB for default connection handling
*/
protected String databaseURL = "jdbc:odbc:myDB";
/**
* User to connect as for default connection handling
*/
protected String databaseUser = "me";
/**
* User to use for default connection handling
*/
protected String databasePassword = "mypassword";
/**
* Connection used by default. The connection is opened the first time it
* is needed and then held open until the appender is closed (usually at
* garbage collection). This behavior is best modified by creating a
* sub-class and overriding the <code>getConnection</code> and
* <code>closeConnection</code> methods.
*/
protected Connection connection = null;
/**
* Stores the string given to the pattern layout for conversion into a SQL
* statement, eg: insert into LogTable (Thread, Class, Message) values
* ("%t", "%c", "%m").
*
* Be careful of quotes in your messages!
*
* Also see PatternLayout.
*/
protected String sqlStatement = "";
/**
* size of LoggingEvent buffer before writting to the database.
* Default is 1.
*/
protected int bufferSize = 1;
/**
* ArrayList holding the buffer of Logging Events.
*/
protected ArrayList buffer;
/**
* Helper object for clearing out the buffer
*/
protected ArrayList removes;
public JDBCAppender() {
super();
buffer = new ArrayList(bufferSize);
removes = new ArrayList(bufferSize);
}
/**
* Adds the event to the buffer. When full the buffer is flushed.
*/
public void append(LoggingEvent event) {
buffer.add(event);
if (buffer.size() >= bufferSize)
flushBuffer();
}
/**
* By default getLogStatement sends the event to the required Layout object.
* The layout will format the given pattern into a workable SQL string.
*
* Overriding this provides direct access to the LoggingEvent
* when constructing the logging statement.
*
*/
protected String getLogStatement(LoggingEvent event) {
return getLayout().format(event);
}
/**
*
* Override this to provide an alertnate method of getting
* connections (such as caching). One method to fix this is to open
* connections at the start of flushBuffer() and close them at the
* end. I use a connection pool outside of JDBCAppender which is
* accessed in an override of this method.
* */
protected void execute(String sql) throws SQLException {
Connection con = null;
Statement stmt = null;
try {
con = getConnection();
stmt = con.createStatement();
stmt.executeUpdate(sql);
} catch (SQLException e) {
if (stmt != null)
stmt.close();
throw e;
}
stmt.close();
closeConnection(con);
//System.out.println("Execute: " + sql);
}
/**
* Override this to return the connection to a pool, or to clean up the
* resource.
*
* The default behavior holds a single connection open until the appender
* is closed (typically when garbage collected).
*/
protected void closeConnection(Connection con) {
}
/**
* Override this to link with your connection pooling system.
*
* By default this creates a single connection which is held open
* until the object is garbage collected.
*/
protected Connection getConnection() throws SQLException {
if (!DriverManager.getDrivers().hasMoreElements())
setDriver("sun.jdbc.odbc.JdbcOdbcDriver");
if (connection == null) {
connection = DriverManager.getConnection(databaseURL, databaseUser,
databasePassword);
}
return connection;
}
/**
* Closes the appender, flushing the buffer first then closing the default
* connection if it is open.
*/
public void close()
{
flushBuffer();
try {
if (connection != null && !connection.isClosed())
connection.close();
} catch (SQLException e) {
errorHandler.error("Error closing connection", e, ErrorCode.GENERIC_FAILURE);
}
this.closed = true;
}
/**
* loops through the buffer of LoggingEvents, gets a
* sql string from getLogStatement() and sends it to execute().
* Errors are sent to the errorHandler.
*
* If a statement fails the LoggingEvent stays in the buffer!
*/
public void flushBuffer() {
//Do the actual logging
removes.ensureCapacity(buffer.size());
for (Iterator i = buffer.iterator(); i.hasNext();) {
try {
LoggingEvent logEvent = (LoggingEvent)i.next();
String sql = getLogStatement(logEvent);
execute(sql);
removes.add(logEvent);
}
catch (SQLException e) {
errorHandler.error("Failed to excute sql", e,
ErrorCode.FLUSH_FAILURE);
}
}
// remove from the buffer any events that were reported
buffer.removeAll(removes);
// clear the buffer of reported events
removes.clear();
}
/** closes the appender before disposal */
public void finalize() {
close();
}
/**
* JDBCAppender requires a layout.
* */
public boolean requiresLayout() {
return true;
}
/**
*
*/
public void setSql(String s) {
sqlStatement = s;
if (getLayout() == null) {
this.setLayout(new PatternLayout(s));
}
else {
((PatternLayout)getLayout()).setConversionPattern(s);
}
}
/**
* Returns pre-formated statement eg: insert into LogTable (msg) values ("%m")
*/
public String getSql() {
return sqlStatement;
}
public void setUser(String user) {
databaseUser = user;
}
public void setURL(String url) {
databaseURL = url;
}
public void setPassword(String password) {
databasePassword = password;
}
public void setBufferSize(int newBufferSize) {
bufferSize = newBufferSize;
buffer.ensureCapacity(bufferSize);
removes.ensureCapacity(bufferSize);
}
public String getUser() {
return databaseUser;
}
public String getURL() {
return databaseURL;
}
public String getPassword() {
return databasePassword;
}
public int getBufferSize() {
return bufferSize;
}
/**
* Ensures that the given driver class has been loaded for sql connection
* creation.
*/
public void setDriver(String driverClass) {
try {
Class.forName(driverClass);
} catch (Exception e) {
errorHandler.error("Failed to load driver", e,
ErrorCode.GENERIC_FAILURE);
}
}
}