Java Discussion Platform: March 2015

Tuesday, 31 March 2015

Basic Introduction Of Apache JMeter

What is JMeter ?

The Apache JMeterTM is pure Java open source software, which was first developed by Stefano Mazzocchi of the Apache Software Foundation, designed to load test functional behavior and measure performance. You can use JMeter to analyze and measure the performance of web application or variety of services. Performance testing means testing a web application against heavy load, multiple and concurrent user traffic. JMeter originally is used for testing Web Application or FTP application. Nowadays, it is used for functional test, database server test etc.

Why JMeter ?

Open source license: JMeter is totally free, allows developer use the source code for the development
Friendly GUI: JMeter is extremely easy to use and doesn't take time to get familiar with it
Platform independent: JMeter is 100% pure Java desktop application. So it can run on multiple platforms
Full multi-threading framework. JMeter allows concurrent and simultaneous sampling of different functions by a separate thread group
Visualize Test Result: Test result can be display in a different format such as chart, table, tree and log file
Easy installation: You just copy and run the *.bat file to run JMeter. No installation needed.
Highly Extensible: You can write your own tests. JMeter also supports visualization plugins allow you extend your testing
Multiple testing strategy: JMeter supports many testing strategies such as Load Testing, Distributed Testing, and Functional Testing.
Simulation: JMeter can simulate multiple users with concurrent threads, create a heavy load against web application under test
Support multi-protocol: JMeter does not only support web application testing, but also evaluate database server performance. All basic protocols such as HTTP, JDBC, LDAP, SOAP, JMS, and FTP are supported by JMeter
Record & Playback - Record the user activity on the browser and simulate them in web application using JMeter
Script Test: Jmeter can be integrated with Bean Shell & Selenium for automated testing.

How does JMeter work ?

JMeter simulates a group of users sending requests to a target server, and return statistics information of target server through graphical diagrams

The completed workflow of JMeter as show in figure below

KEEP WATCHING FOR MORE TUTORIALS.

Thursday, 12 March 2015

Hibernate Issue – Initial SessionFactory Creation Failed.Java.Lang.NoClassDefFoundError: Org/Dom4j/DocumentException

A common Hibernate’s error, this is caused by the missing dependency library – dom4j.

Initial SessionFactory creation failed.java.lang.NoClassDefFoundError: org/dom4j/DocumentException
Exception in thread "main" java.lang.ExceptionInInitializerError
 at com.mkyong.persistence.HibernateUtil.buildSessionFactory(HibernateUtil.java:18)
 at com.mkyong.persistence.HibernateUtil.<clinit>(HibernateUtil.java:8)
 at com.mkyong.common.App.main(App.java:17)
Caused by: java.lang.NoClassDefFoundError: org/dom4j/DocumentException
 at com.mkyong.persistence.HibernateUtil.buildSessionFactory(HibernateUtil.java:13)
 ... 2 more
Caused by: java.lang.ClassNotFoundException: org.dom4j.DocumentException
 at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
 at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
 at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
 ... 3 more

Solution

You can download the library here – http://sourceforge.net/projects/dom4j/files/dom4j/

Add the dependency in Maven’s pom.xml

       <dependency>
  <groupId>dom4j</groupId>
  <artifactId>dom4j</artifactId>
  <version>1.6.1</version>
 </dependency>

Hibernate Issue – An AnnotationConfiguration Instance Is Required To Use

The Hibernate annotation is required “AnnotationConfiguration” instead of normal “Configuration()” to build the session factory.

INFO: Configuration resource: /hibernate.cfg.xml
Initial SessionFactory creation failed.org.hibernate.MappingException: 
An AnnotationConfiguration instance is required to use <mapping class="com.mkyong.common.Stock"/>
Exception in thread "main" java.lang.ExceptionInInitializerError
 at com.mkyong.persistence.HibernateUtil.buildSessionFactory(HibernateUtil.java:19)
 at com.mkyong.persistence.HibernateUtil.<clinit>(HibernateUtil.java:8)
 at com.mkyong.common.App.main(App.java:11)
Caused by: org.hibernate.MappingException: An AnnotationConfiguration instance is required to use <mapping class="com.mkyong.common.Stock"/>
 at org.hibernate.cfg.Configuration.parseMappingElement(Configuration.java:1600)
 at org.hibernate.cfg.Configuration.parseSessionFactory(Configuration.java:1555)
 at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1534)
 at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1508)
 at org.hibernate.cfg.Configuration.configure(Configuration.java:1428)
 at org.hibernate.cfg.Configuration.configure(Configuration.java:1414)
 at com.mkyong.persistence.HibernateUtil.buildSessionFactory(HibernateUtil.java:13)
 ... 2 more

Solution

1. Download the Hibernate annotation library

You can download the library from Hibernate official website

Add the dependency in Maven’s pom.xml

        <!-- Hibernate annotation -->
 <dependency>
  <groupId>hibernate-annotations</groupId>
  <artifactId>hibernate-annotations</artifactId>
  <version>3.3.0.GA</version>
 </dependency>

P.S You may need to include the JBoss repository in order to download the Hibernate annotation library.

<repositories>
    <repository>
      <id>JBoss repository</id>
      <url>http://repository.jboss.com/maven2/</url>
    </repository>
  </repositories>

2. Use AnnotationConfiguration to build session factory

Normal Hibernate XML file mapping is using Configuration()

          return new Configuration().configure().buildSessionFactory();

For Hibernate annotation, you have to change it to “AnnotationConfiguration”

          return new AnnotationConfiguration().configure().buildSessionFactory();

HibernateUtil.java

A full example of “HibernateUtil.java” of using “AnnotationConfiguration” for Hibernate annotation applacation.

package com.mkyong.persistence;
 
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
 
public class HibernateUtil {
 
    private static final SessionFactory sessionFactory = buildSessionFactory();
 
    private static SessionFactory buildSessionFactory() {
        try {
            // Create the SessionFactory from hibernate.cfg.xml
            return new AnnotationConfiguration().configure().buildSessionFactory();
 
        }
        catch (Throwable ex) {
            // Make sure you log the exception, as it might be swallowed
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }
 
    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
 
    public static void shutdown() {
     // Close caches and connection pools
     getSessionFactory().close();
    }
 
}

Hibernate Issue - Org.Hibernate.AnnotationException: Unknown Id.Generator

Problem

Runing the following Hibernate’s annotation sequence generator with PostgreSQL database.

        @Id 
 @Column(name="user_id", nullable=false) 
 @GeneratedValue(strategy = GenerationType.SEQUENCE ,generator="account_user_id_seq")
 private Integer userId;

Hits the following Unknown Id.generator exception.

Caused by: org.hibernate.AnnotationException: Unknown Id.generator: account_user_id_seq
 at org.hibernate.cfg.BinderHelper.makeIdGenerator(BinderHelper.java:413)
 at org.hibernate.cfg.AnnotationBinder.bindId(AnnotationBinder.java:1795)
 at org.hibernate.cfg.AnnotationBinder.processElementAnnotations(AnnotationBinder.java:1229)
 at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:733)

The sequence “account_user_id_seq” is created in PostgreSQL database, what caused the above exception?

Solution

When declaring the Hibernate’s annotation strategy to use “Sequences” as Id generator, try specify the @SequenceGenerator as well, as following

        @Id 
 @Column(name="user_id", nullable=false) 
 @SequenceGenerator(name="my_seq", sequenceName="account_user_id_seq")
 @GeneratedValue(strategy = GenerationType.SEQUENCE ,generator="my_seq")
 private Integer userId;

Hibernate Issue - Remember That Ordinal Parameters Are 1-Based!...

Problem

HibernateTemplate code …

getHibernateTemplate().find("from Domain d 
where d.domainName = :domainName", domainName);

When i execute the above code, i hit the following error message

java.lang.IndexOutOfBoundsException: Remember that ordinal parameters are 1-based!
 ...
 at org.hibernate.impl.AbstractQueryImpl.determineType(AbstractQueryImpl.java:397)
 at org.hibernate.impl.AbstractQueryImpl.setParameter(AbstractQueryImpl.java:369)

Solution

I go inside and study HibernateTemplate.java file and find below code

public List find(final String queryString, final Object[] values) throws DataAccessException {
 return (List) executeWithNativeSession(new HibernateCallback() {
  public Object doInHibernate(Session session) throws HibernateException {
   Query queryObject = session.createQuery(queryString);
   prepareQuery(queryObject);
   if (values != null) {
    for (int i = 0; i < values.length; i++) {
     queryObject.setParameter(i, values[i]);
    }
   }
   return queryObject.list();
  }
 });
}

From code above, the HibernateTemplete is using 0-based instead of 1-based. Is this a spring or hibernate library problem? Since error message stated parameters need to start at 1-based. I tried some solution like change spring or hibernate library, however it’s not working…

It’s seem I’m on a wrong direction, i have to start finding solution at beginning again, first i study my own code…………!!! I cant imaging how careless i am, i made a stupid mistake on my code, this is not spring or hibernate problem, it is my syntax error.

Change from

getHibernateTemplate().find("
    from Domain d where d.domainName = :domainName", domainName);

getHibernateTemplate().find("
    from Domain d where d.domainName = ?", domainName);

Problem solved, code execute without error anymore.

Note
The error message generated by HibernateTemplate is really misleading !!!

Hibernate Issue - Java.Lang.ClassNotFoundException : Javassist.Util.Proxy.MethodFilter

Problem

Using Hibernate 3.6.3, but hits this javassist not found error, see below for error stacks :

Caused by: java.lang.NoClassDefFoundError: javassist/util/proxy/MethodFilter
 ...
 at org.hibernate.tuple.entity.PojoEntityTuplizer.<init>(PojoEntityTuplizer.java:77)
 ... 16 more
Caused by: java.lang.ClassNotFoundException: javassist.util.proxy.MethodFilter
 at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
 at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
 at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
 ... 21 more

Solution

javassist.jar is missing, and you can get the latest from JBoss Maven repositorty.

File : pom.xml

<project ...>
 <repositories>
  <repository>
   <id>JBoss repository</id>
   <url>http://repository.jboss.org/nexus/content/groups/public/</url>
  </repository>
 </repositories>
 
 <dependencies>
  <dependency>
   <groupId>org.hibernate</groupId>
   <artifactId>hibernate-core</artifactId>
   <version>3.6.3.Final</version>
  </dependency>
 
  <dependency>
   <groupId>javassist</groupId>
   <artifactId>javassist</artifactId>
   <version>3.12.1.GA</version>
  </dependency>
 
 </dependencies>
</project>

Hibernate Issue – The Type AnnotationConfiguration Is Deprecated

Problem

Working with Hibernate 3.6, noticed the previous “org.hibernate.cfg.AnnotationConfiguration“, is marked as “deprecated“.

Code snippets …

import org.hibernate.cfg.AnnotationConfiguration;
//...
private static SessionFactory buildSessionFactory() {
 try {
 
  return new AnnotationConfiguration().configure().buildSessionFactory();
 
 } catch (Throwable ex) {
 
  System.err.println("Initial SessionFactory creation failed." + ex);
  throw new ExceptionInInitializerError(ex);
 }
}

The code is still working, just keep displaying the deprecated warning message, is there any replacement for “AnnotationConfiguration” ?

Solution

In Hibernate 3.6, “org.hibernate.cfg.AnnotationConfiguration” is deprecated, and all its functionality has been moved to “org.hibernate.cfg.Configuration“.

So , you can safely replace your “AnnotationConfiguration” with “Configuration” class.

Code snippets …

import org.hibernate.cfg.Configuration;
//...
private static SessionFactory buildSessionFactory() {
 try {
 
  return new Configuration().configure().buildSessionFactory();
 
 } catch (Throwable ex) {
 
  System.err.println("Initial SessionFactory creation failed." + ex);
  throw new ExceptionInInitializerError(ex);
 }
}

Hibernate Issue – Could Not Find C3P0ConnectionProvider

Problem

Configured Hibernate to use “c3p0” connection pool, but hits following warning :

//...
2011-04-25_12:18:37.190 WARN  o.h.c.ConnectionProviderFactory - 
c3p0 properties is specificed, but could not find 
 
org.hibernate.connection.C3P0ConnectionProvider from the classpath,
 these properties are going to be ignored.
2011-04-25_12:18:37.191 INFO  o.h.c.DriverManagerConnectionProvider - 
Using Hibernate built-in connection pool (not for production use!)
//...

Look like “org.hibernate.connection.C3P0ConnectionProvider” is missing?

Solution

Since Hibernate v3.3 (if not mistaken), the “C3P0ConnectionProvider” is moved to another jar file “hibernate-c3p0.jar“. You need to include it, in order to make Hibernate supports c3p0 connection pool.

You can download the “hibernate-c3p0.jar” from JBoss public repository.

File : pom.xml

<project ...>
 
 <repositories>
  <repository>
   <id>JBoss repository</id>
   <url>http://repository.jboss.org/nexus/content/groups/public/</url>
  </repository>
 </repositories>
 
 <dependencies>
 
  <!-- Hibernate c3p0 connection pool -->
  <dependency>
   <groupId>org.hibernate</groupId>
   <artifactId>hibernate-c3p0</artifactId>
   <version>3.6.3.Final</version>
  </dependency>
 
 </dependencies>
</project>