Skip to main content

Basic Log4j tutorial

Step 1 :

create file log4j.properties in $project_home/src/

log4j.appender.portlet = org.apache.log4j.FileAppender
# log file will be in tomcat/logs/
log4j.appender.portlet.File = ${catalina.home}/logs/privatemessage.log
log4j.appender.portlet.Append = false
log4j.appender.portlet.layout = org.apache.log4j.PatternLayout
log4j.appender.portlet.layout.ConversionPattern = %d{ABSOLUTE} [%t] %-5p %-30.30c{2} %x - %m %n

# only log errors
log4j.rootCategory=WARN, portlet
# log trace messages from this package and sub packages
log4j.logger.com.cisco.project=TRACE


Step 2 :

add these lines to web.xml
<context-param>
<param-name>log4jConfigLocation</param-name>
<param-value>classpath:log4j.properties</param-value>
</context-param>

Step 3 :
Use logger in your java classes, before add log4j library to your project classpath
// add imports
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

// define
private static Log logger = LogFactory.getLog(PostLogin.class);

// use this way
logger.trace(" Begin PostLoginHook.... ");

if ( logger.isDebugEnabled() ) {
logger.debug("inside method");
}



Comments

Post a Comment

Popular posts from this blog

Access multiple Databases in JPA

According to JPA specification we can define multiple "persistence-unit" elements (i.e. like below) in persistence.xml file and can easily refer them inside Dao layers as this. public class PolarDaoImpl {     @PersistenceContext(unitName="PolarPU")     protected EntityManager entityManager; -- } public class BearDaoImpl {     @PersistenceContext(unitName="BearPU")     protected EntityManager entityManager; -- } Checkout sample persistence.xml <?xml version="1.0" encoding="UTF-8"?> <persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">     <!-- Database 1 -->     <persistence-unit name="PolarPU" transaction-type="RESOURCE_LOCAL">         <
3 comments
Read more

JPA 2 new feature @ElementCollection explained

@ElementCollection is new annotation introduced in JPA 2.0, This will help us get rid of One-Many and Many-One shitty syntax. Example 1: Stores list of Strings in an Entity @Entity public class Users implements Serializable {     private static final long serialVersionUID = 1L;     @Id     @GeneratedValue(strategy = GenerationType.AUTO)     private Long id;     @ElementCollection     private List<String> certifications = new ArrayList <String> ();     public Long getId() {         return id;     }     public void setId(Long id) {         this.id = id;     }     public List <String> getCertifications() {         return certifications;     }     public void setCertifications(List <String> certifications) {         this.certifications = certifications;     } .. }         Users u = new Users();         u.getCertifications().add("Sun Certified Java Programmer");         em.persist(u); Generated Tables    Users    Co
21 comments
Read more

Reuse JPA Entities as DTO

Note : Major design advantages of JPA Entities are they can detached and used across tiers and networks and later can by merged. Checkout this new way of querying entities in JPA 2.0 String ql = " SELECT new prepclass2.Employee (e.firstname, e.lastname) FROM Employee e "; List<Employee> dtos = em.createQuery(ql).getResultList(); The above query loads all Employee entities but with subset of data i.e. firstname, lastname. Employee entity looks like this. @Entity @Table(name="emp") public class Employee implements Serializable {     private static final long serialVersionUID = 1L;     @Id     @GeneratedValue(strategy = GenerationType.AUTO)     private Long id;     @Column     private String firstname;     @Column     private String lastname;     @Column     private String username;     @Column     private String street;     @Column     private String city;     @Column     private String state;     @Column     private String zipc
11 comments
Read more