Java/Language Basics/Log4j

and assign level and appender to your own logger

   <source lang="java">
 

log4j.logger.ru.foo=DEBUG,FILE

 </source>
   
  
 
  

define a named logger

   <source lang="java">
 

log4j.logger.dataAccessLogger = com.apress.logging.logger

 </source>
   
  
 
  

define the appender named CONSOLE

   <source lang="java">
 

log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender log4j.appender.CONSOLE.conversionPattern=%m%n

 </source>
   
  
 
  

define the appender named FILE

   <source lang="java">
 

log4j.appender.FILE=org.apache.log4j.FileAppender log4j.appender.FILE.File=${user.home}/log.out

 </source>
   
  
 
  

define the root logger with two appenders writing to console and file

   <source lang="java">
 

log4j.rootLogger = DEBUG, CONSOLE, FILE

 </source>
   
  
 
  

Example log4j Configuration File

   <source lang="java">
 

/* Logging In Java with the JDK 1.4 Logging API and Apache log4j by Samudra Gupta Apress Copyright 2003 ISBN:1590590996

• /

//Example log4j Configuration File /*

1. set the level of the root logger to DEBUG and set its appender

as an appender named X log4j.rootLogger = DEBUG, X

1. set the appender named X to be a console appender

log4j.appender.X=org.apache.log4j.ConsoleAppender

1. set the layout for the appender X

log4j.appender.X.layout=org.apache.log4j.PatternLayout log4j.appender.X.layout.conversionPattern=%m%n

• /

// Complex log4j Configuration File /*

1. define the root logger with two appenders writing to console and file

log4j.rootLogger = DEBUG, CONSOLE, FILE

1. define your own logger named com.foo

log4j.logger.ru.foo=com.foo.MyLogger

1. assign appender to your own logger

log4j.logger.ru.foo.appender=FILE

1. define the appender named

FILE log4j.appender.FILE=org.apache.log4j.FileAppender log4j.appender.FILE.File=${user.home}/log.out

1. define the appender named CONSOLE

log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender log4j.appender.CONSOLE.conversionPattern=%m%n log4j.properties

1. set the level of the root logger to DEBUG (the lowest level) and

set its appender

1. as an appender named X

log4j.rootLogger = DEBUG, X

1. set your own logger

log4j.logger.ru.apress.logging.log4j=DEBUG, X

1. set the appender named X to be a console appender

log4j.appender.X=org.apache.log4j.ConsoleAppender

1. set the layout for the appender X

log4j.appender.X.layout=org.apache.log4j.PatternLayout log4j.appender.X.layout.conversionPattern=%p-%m%n

• /

 </source>
   
  
 
  

html.properties: configuring the custom logger

   <source lang="java">
 

log4j.logger.ru.apress.logging.log4j=DEBUG, FILE log4j.appender.FILE=org.apache.log4j.FileAppender log4j.appender.FILE.File=htmlLayout.html log4j.appender.FILE.layout=org.apache.log4j.HTMLLayout log4j.appender.FILE.layout.Title=HTML Layout Demo log4j.appender.FILE.layout.LocationInfo=true

 </source>
   
  
 
  

jdbc.properties configuration file for log4j

   <source lang="java">
 

1. configuring the custom logger

log4j.logger.ru.apress.logging.log4j=DEBUG, DB log4j.appender.DB=org.apache.log4j.jdbc.JDBCAppender log4j.appender.DB.URL=jdbc:odbc:dbdef log4j.appender.DB.user=system log4j.appender.DB.password=manager log4j.appender.DB.sql=INSERT INTO LOGGING_DATA VALUES("%x","%d{yyyy-MM-dd}","%C","%p","%m")

 </source>
   
  
 
  

jms.properties configuration file for JMS

   <source lang="java">
 

1. configuring the custom logger

log4j.logger.ru.apress.logging.log4j=DEBUG, JMS

1. configuring the JMS appender

log4j.appender.JMS=org.apache.log4j.net.JMSAppender log4j.appender.JMS.topicConnectionFactoryBindingName=TopicConnectionFactory log4j.appender.JMS.topicBindingName=loggingTopic

 </source>
   
  
 
  

log4j: A complete example

   <source lang="java">
 

/* Logging In Java with the JDK 1.4 Logging API and Apache log4j by Samudra Gupta Apress Copyright 2003 ISBN:1590590996

• /

import org.apache.log4j.or.ObjectRenderer; import org.apache.log4j.Logger; import org.apache.log4j.spi.Filter; import org.apache.log4j.spi.LoggingEvent; class CustomerOrder {

 /** Holds value of property productName. */
 private String productName;
 /** Holds value of property productCode. */
 private int productCode;
 /** Holds value of property productPrice. */
 private int productPrice;
 /** Creates a new instance of CustomerOrder */
 public CustomerOrder() {
 }
 public CustomerOrder(String name, int code, int price) {
   this.productCode = code;
   this.productPrice = price;
   this.productName = name;
 }
 /**
  * Getter for property productName.
  * 
  * @return Value of property productName.
  */
 public String getProductName() {
   return this.productName;
 }
 /**
  * Setter for property productName.
  * 
  * @param productName
  *            New value of property productName.
  */
 public void setProductName(String productName) {
   this.productName = productName;
 }
 /**
  * Getter for property productCode.
  * 
  * @return Value of property productCode.
  */
 public int getProductCode() {
   return this.productCode;
 }
 /**
  * Setter for property productCode.
  * 
  * @param productCode
  *            New value of property productCode.
  */
 public void setProductCode(int productCode) {
   this.productCode = productCode;
 }
 /**
  * Getter for property productPrice.
  * 
  * @return Value of property productPrice.
  */
 public int getProductPrice() {
   return this.productPrice;
 }
 /**
  * Setter for property productPrice.
  * 
  * @param productPrice
  *            New value of property productPrice.
  */
 public void setProductPrice(int productPrice) {
   this.productPrice = productPrice;
 }

} class ProductFilter extends Filter {

 /** Creates a new instance of ProductFilter */
 public ProductFilter() {
 }
 public int decide(LoggingEvent event) {
   int result = this.ACCEPT;
   //obtaining the message object passed through Logger
   Object message = event.getMessage();
   //checking if the message object is of correct type
   if (message instanceof CustomerOrder) {
     CustomerOrder order = (CustomerOrder) message;
     int productCode = order.getProductCode();
     //checking for the product code greater than 100 only
     if (productCode < 100) {
       result = this.DENY;
     }
   } else {
     //this filter can ignore this, pass to next filter
     result = this.NEUTRAL;
   }
   return result;
 }

} class OrderRenderer implements ObjectRenderer {

 private static final String separator = "-";
 /** Creates a new instance of OrderRenderer */
 public OrderRenderer() {
 }
 public String doRender(Object obj) {
   StringBuffer buffer = new StringBuffer(50);
   CustomerOrder order = null;
   String productName = null;
   int productCode = 0;
   int productPrice = 0;
   //check if the instance is of correct type CustomerOrder
   if (obj instanceof CustomerOrder) {
     order = (CustomerOrder) obj;
     productName = order.getProductName();
     productCode = order.getProductCode();
     productPrice = order.getProductPrice();
     buffer.append(productName);
     buffer.append(separator);
     buffer.append(new Integer(productCode).toString());
     buffer.append(separator);
     buffer.append(new Integer(productPrice).toString());
   }
   return buffer.toString();
 }

} public class ProductFilterDemo {

 private static Logger logger = Logger.getLogger("name");
 /** Creates a new instance of ProductFilterDemo */
 public ProductFilterDemo() {
 }
 public void processOrder(CustomerOrder order) {
   logger.info(order);
 }
 public static void main(String args[]) {
   CustomerOrder order1 = new CustomerOrder("Beer", 101, 20);
   CustomerOrder order2 = new CustomerOrder("Lemonade", 95, 10);
   CustomerOrder order3 = new CustomerOrder("Chocolate", 223, 5);
   ProductFilterDemo demo = new ProductFilterDemo();
   demo.processOrder(order1);
   demo.processOrder(order2);
   demo.processOrder(order3);
 }

} //filter_properties.xml /*

* 
* <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE log4j:configuration SYSTEM
* "log4j.dtd">
* 
* <log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
* 
* <renderer renderedClass="com.apress.business.CustomerOrder"
* renderingClass="com.apress.logging.log4j.renderer.OrderRenderer"> </renderer>
* 
* <appender name="A1" class="org.apache.log4j.ConsoleAppender">
* 
* <layout class="org.apache.log4j.PatternLayout"> <param
* name="ConversionPattern" value="%t %-5p %c{2} - %m%n"/> </layout> <filter
* class="com.apress.logging.log4j.filter.ProductFilter"/> </appender>
* 
* <logger name="com.apress.logging.log4j"> <level value="debug"/> <appender-ref
* ref="A1"/> </logger> </log4j:configuration>
*/

 </source>
   
  
 
  

log4j: advanced log

   <source lang="java">
 

/* Logging In Java with the JDK 1.4 Logging API and Apache log4j by Samudra Gupta Apress Copyright 2003 ISBN:1590590996

• /

import org.apache.log4j.Logger; import org.apache.log4j.NDC; public class AdvancedLogging {

 private static Logger logger = Logger.getLogger("name");
 private String userName = null;
 private double balance;
 /** Creates a new instance of AdvancedLogging */
 public AdvancedLogging(String user) {
   this.userName = user;
 }
 /**
  * Deposit some amount
  */
 public void deposit(double amount) {
   NDC.push(userName);
   balance += amount;
   logger.info("Deposited " + amount + " new balance: " + balance);
   NDC.pop();
 }
 /**
  * withdraw some amount
  */
 public void withdraw(double amount) {
   NDC.push(userName);
   if (balance >= amount) {
     balance -= amount;
     logger.info("Withdrawn " + amount + " new balance: " + balance);
   } else {
     System.out.println("Not enough balance");
     logger.error("Failed to withdraw: balance: " + balance
         + " attempted withdraw: " + amount);
   }
   NDC.pop();
 }
 public static void main(String args[]) {
   AdvancedLogging demo = new AdvancedLogging("sam");
   demo.deposit(100.50);
   demo.withdraw(80);
   demo.withdraw(50);
 }

}

 </source>
   
  
 
  

log4j: asynchronous log

   <source lang="java">
 

/* Logging In Java with the JDK 1.4 Logging API and Apache log4j by Samudra Gupta Apress Copyright 2003 ISBN:1590590996

• /

import org.apache.log4j.AsyncAppender; import org.apache.log4j.ConsoleAppender; import org.apache.log4j.Logger; public class AsyncLogging {

 private static Logger logger = Logger.getLogger("name");
 private AsyncAppender asyncAppender = null;
 private ConsoleAppender consoleAppender = null;
 /** Creates a new instance of AsyncLogging */
 public AsyncLogging() {
   try {
     logger.setAdditivity(false);
     asyncAppender = (AsyncAppender) logger.getRootLogger().getAppender(
         "ASYNC");
     asyncAppender.setBufferSize(4);
   } catch (Exception e) {
     System.out.println("error: " + e.toString());
   }
 }
 /**
  * This method simply logs the messages
  */
 public void doLogging() {
   logger.debug("Hello 1");
   logger.debug("Hello 2");
   logger.debug("Hello 3");
   //logger.debug("Hello 4");
   //logger.debug("Hello 5");
 }
 /**
  * the main method
  */
 public static void main(String args[]) {
   AsyncLogging demo = new AsyncLogging();
   demo.doLogging();
 }

}

 </source>
   
  
 
  

log4j config file: configuring the appender CONSOLE

   <source lang="java">
 

log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender log4j.appender.CONSOLE.layout=org.apache.log4j.TTCCLayout

 </source>
   
  
 
  

log4j config file: configuring the layout TTCCLayout

   <source lang="java">
 

log4j.appender.CONSOLE.layout.ThreadPrinting=false og4j.appender.CONSOLE.layout.ContextPrinting=false log4j.appender.CONSOLE.layout.CategoryPrefixing=false log4j.appender.CONSOLE.layout.DateFormat=RELATIVE

 </source>
   
  
 
  

log4j config file: configuring the named logger

   <source lang="java">
 

log4j.logger.ru.apress.logging.log4j=DEBUG, CONSOLE

 </source>
   
  
 
  

log4j config file: configuring the root logger

   <source lang="java">
 

log4j.rootLogger=DEBUG, CONSOLE

 </source>
   
  
 
  

log4j Configuration File: assign appender to your own logger

   <source lang="java">
 

log4j.logger.ru.foo.appender=FILE

 </source>
   
  
 
  

log4j Configuration File: define the appender named

   <source lang="java">
 

FILE log4j.appender.FILE=org.apache.log4j.FileAppender log4j.appender.FILE.File=${user.home}/log.out

 </source>
   
  
 
  

log4j Configuration File: define the appender named CONSOLE

   <source lang="java">
 

log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender log4j.appender.CONSOLE.conversionPattern=%m%n

 </source>
   
  
 
  

log4j Configuration File: define the root logger with two appenders writing to console and file

   <source lang="java">
 

log4j.rootLogger = DEBUG, CONSOLE, FILE

 </source>
   
  
 
  

log4j Configuration File: define your own logger named com.foo

   <source lang="java">
 

log4j.logger.ru.foo=com.foo.MyLogger

 </source>
   
  
 
  

log4j Configuration File: set the appender named X to be a console appender

   <source lang="java">
 

log4j.appender.X=org.apache.log4j.ConsoleAppender

 </source>
   
  
 
  

log4j Configuration File: set the layout for the appender X

   <source lang="java">
 

log4j.appender.X.layout=org.apache.log4j.PatternLayout log4j.appender.X.layout.conversionPattern=%m%n

 </source>
   
  
 
  

log4j Configuration File: #set the level of the root logger to DEBUG and set its appender as an appender named X

   <source lang="java">
 

log4j.rootLogger = DEBUG, X

 </source>
   
  
 
  

log4j: File Based Logg Demo

   <source lang="java">
 

/* Logging In Java with the JDK 1.4 Logging API and Apache log4j by Samudra Gupta Apress Copyright 2003 ISBN:1590590996

• /

import org.apache.log4j.*; public class FileBasedLoggingDemo implements Runnable {

 private static Logger logger = Logger.getLogger("filename");
 /** Creates a new instance of FileBasedLoggingDemo */
 public FileBasedLoggingDemo() {
 }
 /**
  * This method is called by the application. This method creates a new
  * thread to start logging
  */
 public void doLogging() {
   Thread t = new Thread(this);
   t.start();
 }
 /**
  * The thread"s run() method, which does repeated logging at an interval of
  * 60secs.
  */
 public void run() {
   int count = 1;
   while (true) {
     //logging information
     try {
       logger.debug("Logging the information..." + count);
       Thread.sleep(60 * 1000);
       count++;
     } catch (Exception e) {
       logger.warn("Exception occured", e);
     }
   }
 }
 /**
  * the main method
  */
 public static void main(String args[]) {
   FileBasedLoggingDemo demo = new FileBasedLoggingDemo();
   demo.doLogging();
 }

}

 </source>
   
  
 
  

log4j: layout demo

   <source lang="java">
 

/* Logging In Java with the JDK 1.4 Logging API and Apache log4j by Samudra Gupta Apress Copyright 2003 ISBN:1590590996

• /

import org.apache.log4j.Logger; import org.apache.log4j.ConsoleAppender; import org.apache.log4j.TTCCLayout; import org.apache.log4j.NDC; public class LayoutDemo {

 private static Logger logger = Logger.getLogger("name");
 private ConsoleAppender appender = null;
 private TTCCLayout layout = null;
 /** Creates a new instance of LayoutDemo */
 public LayoutDemo() {
   //set the parent additivity to false
   logger.setAdditivity(false);
   //initialize the layout
   layout = new TTCCLayout("yyyy-MM-dd");
   //initialize the console appender with the layout
   appender = new ConsoleAppender(layout, "System.out");
   //adding the console appender to the logger
   logger.addAppender(appender);
 }
 public void computeSquareRoot(double number) {
   NDC.push(new Double(number).toString());
   double sqrt = Math.sqrt(number);
   logger.info("The sqrt value: " + sqrt);
   NDC.pop();
 }
 public static void main(String args[]) {
   LayoutDemo demo = new LayoutDemo();
   demo.ruputeSquareRoot(22);
   demo.ruputeSquareRoot(44);
 }

}

 </source>
   
  
 
  

log4j: log and servlet

   <source lang="java">
 

import javax.servlet.*; import javax.servlet.http.*; import java.io.PrintWriter; import java.io.IOException; import org.apache.log4j.*; public class LoggingServlet extends HttpServlet {

   private static Logger logger =Logger.getLogger(LoggingServlet.class);
   public void doPost(HttpServletRequest req, HttpServletResponse res)
                      throws IOException, ServletException
   {
       logger.info("invoked the LoggingServlet...");
       PrintWriter writer = res.getWriter();
       writer.println("Check your web server console...");
       writer.flush();
       writer.close();
   }

}

 </source>
   
  
 
  

log4j.properties: daily layout

   <source lang="java">
 

log4j.appender.DAILY.layout=org.apache.log4j.PatternLayout log4j.appender.DAILY.layout.conversionPattern=%p - %m%n

 </source>
   
  
 
  

log4j.properties: file layout

   <source lang="java">
 

log4j.appender.FILE.layout=org.apache.log4j.PatternLayout log4j.appender.FILE.layout.conversionPattern=%p - %m%n

 </source>
   
  
 
  

log4j.properties: rolling layout

   <source lang="java">
 

log4j.appender.ROLLING.layout=org.apache.log4j.PatternLayout log4j.appender.ROLLING.layout.conversionPattern=%p - %m%n

 </source>
   
  
 
  

log4j.properties: set the appender CONSOLE

   <source lang="java">
 

log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender

 </source>
   
  
 
  

log4j.properties: set the appender DAILY

   <source lang="java">
 

log4j.appender.DAILY=org.apache.log4j.DailyRollingFileAppender log4j.appender.DAILY.File=${user.home}/daily.log log4j.appender.DAILY.DatePattern="." yyyy-MM-dd-HH-mm

 </source>
   
  
 
  

log4j.properties: set the appender FILE

   <source lang="java">
 

log4j.appender.FILE=org.apache.log4j.FileAppender log4j.appender.FILE.File=${user.home}/out.log

 </source>
   
  
 
  

log4j.properties: set the appender ROLLING

   <source lang="java">
 

log4j.appender.ROLLING=org.apache.log4j.RollingFileAppender log4j.appender.ROLLING.File=${user.home}/rolling.log log4j.appender.ROLLING.MaxFileSize=1KB

 </source>
   
  
 
  

log4j.properties: set the layout for the appenders

   <source lang="java">
 

log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout log4j.appender.CONSOLE.layout.conversionPattern=%p - %m%n

 </source>
   
  
 
  

log4j.properties: set the level of the root logger to DEBUG (the lowest level) and set its appenders named DEBUG and CONSOLE

   <source lang="java">
 

log4j.rootLogger = DEBUG, CONSOLE

 </source>
   
  
 
  

log4j.properties: set your own logger

   <source lang="java">
 

log4j.logger.ru.apress.logging.log4j=DEBUG, FILE, ROLLING, DAILY

 </source>
   
  
 
  

log4j: simple log

   <source lang="java">
 

/* Logging In Java with the JDK 1.4 Logging API and Apache log4j by Samudra Gupta Apress Copyright 2003 ISBN:1590590996

• /

import org.apache.log4j.Logger; public class SimpleLogging {

   /** Creates a new instance of SimpleLogging */
   public SimpleLogging() {
   }
   /**
    * @param args the command line arguments
    */
   public static void main(String[] args) {
       Logger logger =Logger.getLogger("name");
       logger.info("Hello this is an info message");
   }

}

 </source>
   
  
 
  

Logging Servlet with log4j

   <source lang="java">
 

import javax.servlet.*; import javax.servlet.http.*; import java.io.PrintWriter; import java.io.IOException; import org.apache.log4j.*; public class LoggingServlet extends HttpServlet {

   private static Logger logger = Logger.getLogger(LoggingServlet.class);
   public void doPost(HttpServletRequest req, HttpServletResponse res)
                      throws IOException, ServletException
   {
       logger.info("invoked the LoggingServlet...");
       PrintWriter writer = res.getWriter();
       writer.println("Check your web server console...");
       writer.flush();
       writer.close();
   }

}

 </source>
   
  
 
  

nt.properties for NT configuration

   <source lang="java">
 

1. configuring the custom logger

log4j.logger.ru.apress.logging.log4j=DEBUG, NT

1. configuring the NT appender

log4j.appender.NT=org.apache.log4j.nt.NTEventLogAppender log4j.appender.NT.layout=org.apache.log4j.SimpleLayout

 </source>
   
  
 
  

Pass the configuration file and configuration class

   <source lang="java">
 

java -Dlog4j.configuration=config file yourApp java -Dlog4j.configurationClass=config class yourApp

 </source>
   
  
 
  

set the appender named testAppender to be a console appender

   <source lang="java">
 

log4j.appender.testAppender=org.apache.log4j.ConsoleAppender

 </source>
   
  
 
  

set the layout for the appender testAppender

   <source lang="java">
 

log4j.appender.testAppender.layout=org.apache.log4j.PatternLayout log4j.appender.testAppender.layout.conversionPattern=%m%n

 </source>
   
  
 
  

set the level of the root logger to DEBUG and set its appender as an appender named testAppender

   <source lang="java">
 

log4j.rootLogger = DEBUG, testAppender

 </source>
   
  
 
  

smtp.properties for EMail based logging

   <source lang="java">
 

1. configuring the custom logger

log4j.logger.ru.apress.logging.log4j=DEBUG, SMTP

1. configuring the SMTP appender

log4j.appender.SMTP=org.apache.log4j.net.SMTPAppender log4j.appender.SMTP.SMTPHost=smtp.mail.yahoo.ru log4j.appender.SMTP.to=clientname@mailserver.ru log4j.appender.SMTP.subject=Testing the appender log4j.appender.SMTP.from=yourname@mailserver.ru log4j.appender.SMTP.layout=org.apache.log4j.SimpleLayout

 </source>
   
  
 
  

xml.properties: configuring the custom logger

   <source lang="java">
 

log4j.logger.ru.apress.logging.log4j=DEBUG, FILE log4j.appender.FILE=org.apache.log4j.FileAppender log4j.appender.FILE.File=xmlLayout.xml log4j.appender.FILE.layout=org.apache.log4j.xml.XMLLayout log4j.appender.FILE.layout.LocationInfo=true

 </source>