dot kam - be kind, do good

hibernate / java / spring — Comments Off
26
Sep 10

Money Making Project

For the past several years most of my projects were based on Spring and Hibernate. And what I keep seeing is how people struggle to understand how the two are working together.

So going from project to project, I have to repeat the same spiel over and over again to get people up to speed.

Since I believe that the most effective way to LEARN is to DO, I create simple examples for people to play with / to complete / to analyze, etc..

So “Money Making Project” is one of such examples. It comfortably lives at github’s luxury apartments, so anybody can “git clone” / “fork” and play with it.

Besides making money, this project also demos things such as:

A way to structure a project

Maven based structure ( hence can be easily used by gradle ). Configuration and property files organized under “META-INF/conf”, “META-INF/props”, etc..

A way to separate Spring configs

“tx-spring-config.xml”, “persistence-spring-config.xml”, “service-spring-config.xml”, “repository-spring-config.xml” and “application-context.xml” that includes them all

Properties via PropertyPlaceholderConfigurer

<context:property-placeholder location="classpath:META-INF/props/env.properties"/>

Hibernate overall configuration file

That is injected into AnnotationSessionFactoryBean

Hibernate Named Queries

That are linked to the Hibernate overall config

<mapping resource="META-INF/conf/hibernate/mapping/startup-bank-named-queries.xml"/>

Spring’s DAO / Hibernate Exception Translation

Via @Repository and “PersistenceExceptionTranslationPostProcessor”

Simple CRUD Repository

public interface MoneyRepository {
 
    public void make( MoneyRoll moneyRoll );        // C
    public MoneyRoll find( Long id );                       // R
    public void update( MoneyRoll moneyRoll );     // U
    public void takeOut( MoneyRoll moneyRoll );    // D
}

with a Hibernate based implementation

Transaction Management with Spring AOP

Declarative, on a Service Level, using “aop:config”, “tx:advice” namespaces

Spring Testing

With SpringJUnit4ClassRunner, ContextConfiguration, etc..

Using Embeded in-memory H2 Database for Testing

<jdbc:embedded-database id="dataSource" type="H2"/>

Hibernate Logging

Most useful hibernate “log4j.logger” properties

Demoing how important Transaction is for Hibernate Sessions

“HibernateSessionNotBoundToThreadIntegrationTest” for the second (after LazyInitializationException ) most common Hibernate exception: “No Hibernate Session bound to thread, and configuration does not allow creation of non-transactional one here”

money / spel / spring — Comments Off
10
Sep 10

Spring Expression Language: Calling a Method with Parameters

Have you ever wanted to win $1,000,000 with a single SpEL ( Spring Expression Language ) call? Well, now you can, and here is how.

Let’s say there is a Lottery that deposits money to a winner’s bank account and congratulates the winner:

private class Lottery {
    // ...
    public String congratulateWinner( String name, BigDecimal amount, Date date ) {
    	String now = new SimpleDateFormat( "MM-dd-yyyy" ).format( date );
    	String cash = new DecimalFormat( "$#,###,###" ).format( amount.doubleValue() );
 
    	return "Congratulations " + name + "! " +
    	       "Today is " + now + ", and it's your lucky day, because " +
    	       "you just won " + cash + "!";
    }
}

Here is how to make Anatoly win money with SpEL:

"congratulateWinner( 'Anatoly', #amount, #date )"

( of course, let’s not forget to set an amount to at least a million dollars ).

And here is a million dollar unit test:

@Test
public void shouldInvokeMethodWithParameters() {
 
    Lottery lottery = new Lottery();
 
    GregorianCalendar calendar = new GregorianCalendar();
    calendar.set( 2010, 8, 10 );
 
    BigDecimal amount = BigDecimal.valueOf( 1000000.00 );
 
    // letting SPEL know about the "lottery", the "amount" won, and the "date"
    EvaluationContext context = new StandardEvaluationContext( lottery );
    context.setVariable( "amount", amount );
    context.setVariable( "date", calendar.getTime() );
 
    ExpressionParser parser = new SpelExpressionParser();
 
    // using '#' to identify a variable ( NOTE: #this, #root are reserved variables )
    Expression exp = parser.parseExpression( "congratulateWinner( 'Anatoly', #amount, #date )" );
 
    String congratulations = ( String ) exp.getValue( context );	
    assertEquals( "Congratulations Anatoly! " + 
                  "Today is 09-10-2010, and it's your lucky day, because you just won $1,000,000!", 
                  congratulations );
}

(!) Do not write code that does not earn you money :)

aop / aspectj / groovy / java — Comments Off
09
Sep 10

Check If The Aspect Was Applied

Let’s say you have an aspect defined that will be applied to a class:

<bean id="someComponent"
      class="org.dotkam.SomeComponent" />
 
<aop:config>
	<aop:aspect ref="someAspect">
		<aop:around method="someMethod"
                            pointcut="execution(public * org.dotkam.SomeComponent.*(..))" />
	</aop:aspect>
</aop:config>

and you of course have “proxy-target-class” set to “true”:

<aop:aspectj-autoproxy proxy-target-class="true"/>

Here is how to check if the aspect was applied:

import static org.junit.Assert.assertTrue;
import net.sf.cglib.proxy.Enhancer;
 
  ... ...
@Resource(name="someComponent")
SomeComponent someComponent
 
  ... ...
assertTrue( Enhancer.isEnhanced( someComponent.getClass() ) );

Behind the scenes it is enhanced with CGLIB’s Enhancer that has a convenient isEnhanced method.

Useful when developing aspects.

NOTE: The above is true given, of course, that this is THE ONLY aspect applied to this component.

php — Comments Off
08
Sep 10

Convert String to Map in PHP

Let’s say I would like to have a PHP line:

image( "src => images/logo.png", "class => right", "alt => Company Logo" );

to generate a full blown HTML <img> tag:

<img src="http://www.dotkam.com/images/company-logo.png" class="right" alt="Company Logo">

For this I would need to translate these three function parameters:

"src => images/logo.png", "class => right", "alt => Company Logo"

into a MAP ( yes, PHP calls it an array, but it is in fact a MAP ):

imageTag (
    'src' => 'images/logo.png'
    'class' => 'right'
    'alt' => 'Company Logo'
)

Here is how it is done:

function image( ) {
 
    $validAttributes = array( 'src', 'class', 'alt' );
 
    foreach ( func_get_args() as $attr ) {
    	$attrMap = explode( ' => ', $attr ); 
    	if ( in_array( $attrMap[0], $validAttributes ) ) {
    		$imageAttrMap[ $attrMap[0] ] = $attrMap[1];
    	}
    	else {
    	    die( 'Configuration Problem: ['.$attrMap[0].'] is not a valid &lt;img&gt; attribute.' );
    	}
    }
 
    // .... validate 'src' is there, append imgTag string with all the attrs, echo it...
}

outlook — Comments Off
26
Aug 10

Cannot Start Microsoft Outlook. Cannot Open the Outlook Window

Sometimes I have to work on Windows boxes… Here is the fix:

C:\Program Files\Microsoft Office\Office12>outlook.exe /resetnavpane

kam
one of those blogs

Money Making Project

Spring Expression Language: Calling a Method with Parameters

Check If The Aspect Was Applied

Convert String to Map in PHP

Cannot Start Microsoft Outlook. Cannot Open the Outlook Window

here is more about

kamone of those blogs

Money Making Project

Spring Expression Language: Calling a Method with Parameters

Check If The Aspect Was Applied

Convert String to Map in PHP

Cannot Start Microsoft Outlook. Cannot Open the Outlook Window

here is more about

kam
one of those blogs