Log4j with multiple appenders using xml file.

Please follow the following program to understand log4j implementation for multiple appenders using xml file.

Java : MultipleAppenders

import org.apache.log4j.Logger;

import org.apache.log4j.xml.DOMConfigurator;

public class MultipleAppenders {

      private static final Logger logger = Logger.getLogger(MultipleAppenders.class);

      public static void main(String[] args) {

            DOMConfigurator.configure("log.xml");

            logger.debug("Debug Message.");// Method to Method.

            logger.info("Info Message.");// Information passing and recieving.

            logger.warn("Warning Message.");// Retrying again.

      }

}

XML: log.xml

<xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration xmlns:log4j='http://jakarta.apache.org/log4j/'>

      <appender name="Console" class="org.apache.log4j.ConsoleAppender">

            <layout class="org.apache.log4j.PatternLayout">

                  <param name="ConversionPattern" value="%p %c - %m%n" />          

            </layout>        

      </appender>

      <appender name="Html" class="org.apache.log4j.FileAppender">

            <param name="File" value="sample.html"/>       

            <layout class="org.apache.log4j.HTMLLayout"/>                    

      </appender>
      <appender name="File" class="org.apache.log4j. FileAppender ">
            <param name="File" value="sample.log"/>

            <layout class="org.apache.log4j.PatternLayout">                   

                  <param name="ConversionPattern" value="%p %c - %m%n" />           

            </layout>        

      </appender>

      <root>

            <level value="trace" />

            <appender-ref ref="Console" />

            <appender-ref ref="File" />

            <appender-ref ref="Html" />

      </root>

</log4j:configuration>

Log4j with multiple appenders using properties.

Please follow the following program to understand log4j implementation for multiple appenders using properties file.

Java : MultipleAppenders

import org.apache.log4j.Logger;

import org.apache.log4j.PropertyConfigurator;

public class MultipleAppenders {

      private static final Logger logger = Logger.getLogger(MultipleAppenders.class);

      public static void main(String[] args) {

            PropertyConfigurator.configure("log.properties");

            logger.debug("Debug Message.");// Method to Method.

            logger.info("Info Message.");// Information passing and recieving.

            logger.warn("Warning Message.");// Retrying again.

      }

}

Properties: log.properties

log4j.rootLogger=DEBUG, Console, File, Html

#Console Appender

log4j.appender.Console=org.apache.log4j.ConsoleAppender

log4j.appender.Console.layout=org.apache.log4j.PatternLayout

log4j.appender.Console.layout.ConversionPattern=%d %p %c --> %M - %m%n

log4j.appender.Console.Threshold = DEBUG

#File Appender

log4j.appender.File=org.apache.log4j.FileAppender

log4j.appender.File.File=file.log

log4j.appender.File.layout=org.apache.log4j.PatternLayout

log4j.appender.File.layout.ConversionPattern=%d %p %c --> %M - %m%n

log4j.appender.File.Threshold = WARN

#File Appender with HTMLLayout

log4j.appender.Html=org.apache.log4j.FileAppender

log4j.appender.Html.File=file.html

log4j.appender.Html.layout=org.apache.log4j.HTMLLayout

log4j.appender.Html.Threshold = TRACE

Log4j using XML configuration.

Please follow the following program to understand log4j implementation using xml file.

Here I have used console appender to log the events.

Java : XMLConfigurationDemo

import org.apache.log4j.Logger;

import org.apache.log4j.xml.DOMConfigurator;

public class XMLConfigurationDemo {

      private static final Logger logger = Logger.getLogger(XMLConfigurationDemo.class);

      public static void main(String[] args) {

            DOMConfigurator.configure("log.xml");

            logger.trace("Trace Message.");// Point to Point.

            logger.debug("Debug Message.");// Method to Method.

      }

}

XML:log.xml

<xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration xmlns:log4j='http://jakarta.apache.org/log4j/'>

      <appender name="Console" class="org.apache.log4j.ConsoleAppender">

            <layout class="org.apache.log4j.PatternLayout">

                  <param name="ConversionPattern" value="%p %c - %m%n" />

            </layout>

      </appender>

      <root>

            <level value="trace" />

            <appender-ref ref="Console" />

      </root>

</log4j:configuration>

Log4j using properties file.

Please follow the following program to understand log4j implementation.

Here I have used console appender to log the events.

Java File: PropertyConfiguratorDemo

import org.apache.log4j.Logger;

import org.apache.log4j.PropertyConfigurator;

public class PropertyConfiguratorDemo {

      private static final Logger logger = Logger.getLogger(PropertyConfiguratorDemo.class);

      public static void main(String[] args) {

            PropertyConfigurator.configure("log.properties");

            logger.trace("Trace Message.");//Point to Point.

            logger.debug("Debug Message.");//Method to Method.         

            logger.info("Info Message.");//Information passing and recieving.

            logger.warn("Warning Message.");//Retrying again.

            logger.error("Error Message.");//Error occured and can continue further.

            logger.fatal("Fatal Message.");//Error occured and needs to stop application.

      }

}

Properties File: log.properties

log4j.rootLogger=DEBUG, Console

log4j.appender.Console=org.apache.log4j.ConsoleAppender

log4j.appender.Console.layout=org.apache.log4j.PatternLayout

log4j.appender.Console.layout.ConversionPattern=%d %p %c --> %M - %m%n

Output:

2012-05-31 16:19:36,781 DEBUG com.lenin.log4j.PropertyConfiguratorDemo --> main - Debug Message.

2012-05-31 16:19:36,781 INFO com.lenin.log4j.PropertyConfiguratorDemo --> main - Info Message.

2012-05-31 16:19:36,781 WARN com.lenin.log4j.PropertyConfiguratorDemo --> main - Warning Message.

2012-05-31 16:19:36,781 ERROR com.lenin.log4j.PropertyConfiguratorDemo --> main - Error Message.

2012-05-31 16:19:36,781 FATAL com.lenin.log4j.PropertyConfiguratorDemo --> main - Fatal Message.

Pattern Descriptions in Log4j

Please follow the following program to understand the various letters used for pattern in log4j.

import java.io.IOException;

import org.apache.log4j.Appender;

import org.apache.log4j.ConsoleAppender;

import org.apache.log4j.Layout;

import org.apache.log4j.Logger;

import org.apache.log4j.PatternLayout;

public class PatternDescriptions {

      private static final Logger logger = Logger.getLogger(PatternDescriptions.class);

      public static void main(String[] args) throws IOException {

            Layout layout = new PatternLayout("%c %C %d %F %l %L %m %M %p %t %n");

            //c --> Used to output the category of the logging event.

            //C --> Used to output the fully qualified class name of the caller.

            //d --> Used to output the date of the logging event.

            //F --> Used to output the file name where the logging request was issued.

            //l --> Used to output location information of the caller which generated the logging event.

            //L --> Used to output the line number from where the logging request was issued.

            //m --> Used to output the application supplied message associated with the logging event.

            //M --> Used to output the method name where the logging request was issued.

            //p --> Used to output the priority of the logging event.

            //t --> Used to output the name of the thread that generated the logging event.

            //n --> Outputs the platform dependent line separator character or characters.

            Appender appender = new ConsoleAppender(layout);

            logger.addAppender(appender);

            logger.trace("Trace Message.");

            logger.debug("Debug Message.");

            logger.info("Info Message.");

            logger.warn("Warning Message.");

            logger.error("Error Message.");

            logger.fatal("Fatal Message.");

      }

}

Logger with Java Configuration

Please follow the following program to implement log4j with Java Configuration and use the provided scenario's to use the specific logger methods.

import java.io.IOException;

import org.apache.log4j.Appender;

import org.apache.log4j.FileAppender;

import org.apache.log4j.Layout;

import org.apache.log4j.Logger;

import org.apache.log4j.PatternLayout;

public class JavaLoggerDemo {

      private static final Logger logger = Logger.getLogger(JavaLoggerDemo.class);

      public static void main(String[] args) throws IOException {

            Layout layout = new PatternLayout("%-4r [%t] %-5p %c %m %n");

            Appender appender = new FileAppender(layout, "hello.log");

            logger.addAppender(appender);

            logger.trace("Trace Message.");

            logger.debug("Debug Message.");

            logger.info("Info Message.");

            logger.warn("Warning Message.");

            logger.error("Error Message.");

            logger.fatal("Fatal Message.");

      }

}

Logger with BasicConfigurator.

Please follow the following program to implement log4j with BasicConfigurator and use the provided scenario's to use the specific logger methods.

import org.apache.log4j.BasicConfigurator;

import org.apache.log4j.Logger;

public class BasicConfiguratorDemo {

      private static final Logger logger = Logger.getLogger(BasicConfiguratorDemo.class);

      public static void main(String[] args) {

            BasicConfigurator.configure();

            logger.trace("Trace Message.");

            logger.debug("Debug Message.");

            logger.info("Info Message.");

            logger.warn("Warning Message.");

            logger.error("Error Message.");

            logger.fatal("Fatal Error Message.");

      }

}

Checking Prime in java

      public class Prime {

            public boolean isPrime(int n) {

                  if (n < 2) {

                      return false;

                  }

                  if (n == 2) {

                      return true;

                  }

                  if (n % 2 == 0) {

                      return false;

                  }

                  int sqrt = (int) Math.sqrt(n);

                  for (int i = 3; i <= sqrt; i += 2) {

                        if (n % i == 0) {

                           return false;

                        }

                  }

                  return true;

            }

      }