The following is the steps you do for enable logging
1. Download log4j-1.2.16.jar from apache web site and put this in your WEB-INF/lib folder
2. In your web.xml ( preferable your first servlet that executes )
init-param
3. Create a simple text file log4j.properties and place under WEB-INF folder of web application
---
log4j.rootLogger=DEBUG, R
log4j.rootLogger=TRACE, R
log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=${catalina.home}/logs/myapplication.log
log4j.appender.R.MaxFileSize=10MB
log4j.appender.R.MaxBackupIndex=10
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n
---
4. a) Say in Login servlet init() method
String log4jLocation = config.getInitParameter("log4j-properties-location");
ServletContext sc = config.getServletContext();
if (log4jLocation == null)
{
System.err.println("*** No log4j-properties-location init param, so initializing log4j with BasicConfigurator");
BasicConfigurator.configure();
} else
{
String webAppPath = sc.getRealPath("/");
String log4jProp = webAppPath + log4jLocation;
File yoMamaYesThisSaysYoMama = new File(log4jProp);
if (yoMamaYesThisSaysYoMama.exists()) {
System.out.println("Initializing log4j with: " + log4jProp);
PropertyConfigurator.configure(log4jProp);
} else {
System.err.println("*** " + log4jProp + " file not found, so initializing log4j with BasicConfigurator");
BasicConfigurator.configure();
}
}
mlog.info("LOG4J initialization for CCM User application successful.");
...
4. b )
In the servlet class ( in post method or what have you ) and POJO class deployed
At start declare
Logger mlog = Logger.getLogger(some.class);
..
..
// some action
mlog.info("Inside 'Add UC1 ' request processing.");
mlog.trace("Query executed " + ps);
mlog.trace(ackmsg);
mlog.error(ex.getMessage());
5. Run the application perform actions that would generate these logs.
6. Go to TOMCAT installation %HOME% and open myapplication.log in a text editor.
That it ; you have enhanced traceability of your functionailty you coded.
References :
http://www.avajava.com/tutorials/lessons/how-do-i-initialize-log4j-in-a-web-application.html
