Here is the code for ServletLogAppender.java. Basically, all you need to do
to use it is put the right "appender" section in your log4j properties:
log4j.[[category]] = ... , servletAppender, ...
log4j.servletAppender=com.vecna.servlet.ServletLogAppender
and be sure to call ServletLogAppender.setServletContext(...) at least once
prior to use. The easiest way to do this is to initialize Log4j from within
a servlet context loader or a load-on-startup servlet, when you have the
servlet context object available.
The comments reference Log4jConfigurator, which is servlet context listener
that boils down to this:
public void contextInitialized (ServletContextEvent sce) {
Properties props = [[ grab properties from somewhere ]];
PropertyConfigurator.configure(props);
ServletLogAppender.setServletContext(sce.getServletContext());
}
Hope you find it useful!
-- Bill
--------------------------------------
package com.vecna.servlet;
import org.apache.log4j.AppenderSkeleton;
import org.apache.log4j.Priority;
import org.apache.log4j.spi.ThrowableInformation;
import org.apache.log4j.spi.LoggingEvent;
import javax.servlet.ServletContext;
/**
* ©1998-2001 Vecna Technologies, Inc. All Rights Reserved.
* <br>$Source: /home/cvsroot/webtools/src/servlet/ServletLogAppender.java,v
$
*
* Wrapper class that adapts a servlet context's logger to work within
* the log4j framework.
* <p>
*
* This appender cannot be used until the setServletContext method is
* called. If you initialize Log4j using the Log4jConfigurator class,
* this will be done for you. The servletContext property is static;
* because each webapp gets its own classloader there is a one-to-one
* mapping between servlet contexts and instances of
* ServletLogAppender.class.
*
* @author Bill Schneider ([EMAIL PROTECTED])
*/
public class ServletLogAppender extends AppenderSkeleton {
/**
* Servlet Context
*/
private static ServletContext s_sctx;
/**
* Sets the servlet context for all ServletLogAppenders within
* the current class loader (one per webapp).
* Logging events will be appended to the servlet context's logger.
* @param sctx the servlet context
*/
public static void setServletContext(ServletContext sctx) {
s_sctx = sctx;
}
/**
* Closes this appender. This is a no-op.
*/
public void close() {
// do nothing
}
/**
* Always returns false because the formatting of the log statement
* is handled by the servlet context, not by log4j
* @return always false
*/
public boolean requiresLayout() {
return false;
}
/**
* Logs <code>event</code> into the servlet context by calling
* context.log.
*/
protected void append(LoggingEvent event) {
if (s_sctx == null) {
throw new IllegalStateException
("ServletLogAppender.append called before setServletContext");
}
String errorDescription = event.getRenderedMessage();
ThrowableInformation ti = event.getThrowableInformation();
if (ti != null) {
Throwable t = ti.getThrowable();
s_sctx.log(errorDescription, t);
} else {
s_sctx.log(errorDescription);
}
}
}
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