spring and tdd

8/7/2019 Spring and TDD

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Facilitate TDD with the

Spring FrameworkBy: Mike Shoemaker


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What is Spring?

Spring provides a light-weight solution for building

enterprise-ready applications, while still supporting thepossibility of using declarative transaction management,remote access to your logic using RMI or webservices,mailing facilities and various options in persisting yourdata to a database. Spring provides an MVC framework,

transparent ways of integrating AOP into your software anda well-structured exception hierarchy including automaticmapping from proprietary exception hierarchies.


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Spring Modules


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Springs Mission? J2EE should be easier to use

It's best to program to interfaces, rather thanclasses. Spring reduces the complexity cost of using interfaces to zero.

JavaBeans offer a great way of configuringapplications.

OO design is more important than anyimplementation technology, such as J2EE.

Checked exceptions are overused in Java. A

framework shouldn't force you to catch exceptionsyou're unlikely to be able to recover from.

Testability is essential, and a framework such asSpring should help make your code easier to test.


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Lightweight Container?

Core usage does not impose unwantedcompile time dependencies like EJB

Loosely Coupled Components

Unit testing is possible againPOJOs


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Role of the Container

AKA BeanFactory

Loads Bean denitions ( XML )Instantiates Beans on behalf of client

Congure dependencies via XML

Replaces Factory methods for object creation


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Singleton Beans

Default conguration

Bean instance is shared

Lifecycle is managed by BeanFactory

EfcientGood for Stateless operations


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Prototype Beans

BeanFactory offers a new instance upon eachclient request

BeanFactory cannot manage lifecycle since itloses track of the bean after it hands it off

Semantically equal to the new keyword


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Sample Bean

package com.acme;

public class MyBean {private String state;

public String getState() {return state;

}

public void setState(String state) {this.state = state;

} }


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How do I get a bean?// String Array of bean denition leString[] paths = {"applicationContext.xml"};

// Load bean denitionsApplicationContext ctx = new ClassPathXmlApplicationContext(paths);

// Code to retrieve bean from BeanFactoryMyBean bean = (MyBean)ctx.getBean(myBean);


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ApplicationContext

Extends BeanFactory functionality

Can initialize singleton beans upon load

Can lazy load beans

Provides i18n supportSupports lifecycle events


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Dependency Injection

Synonymous with Inversion of Control (IOC)

Sometimes referred to as JNDI in reverse

Hollywood Principal

Dont call me, Ill call youDI coined by Martin Fowler


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Types of Dependency

InjectionInterface Dependent ( BAD )

AvalonConstructor Based

Pico Container

Setter Based

Spring


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Example of Constructor

Based Injectioncom.mysql.jdbc.Driver

jdbc:mysql://localhost:3306/myDSfredpassword


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Datasource datasource = .........

// Instantiate passing datasource in constructorLoginDAO dao = new LoginDAOJDBC(datasource);

Equivalent Java Code


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Example of Setter

Based Injection

com.mysql.jdbc.Driver

jdbc:mysql://localhost:3306/myDSfredpassword


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Equivalent Java CodeDatasource datasource = .........

// InstantiateLoginDAO dao = new LoginDAOJDBC();

// set data source that was acquired previouslydao.setDatasource(datasource);


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References

http://www.springframework.orgSpring Live

Spring In Action

Pro Spring


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Group Exercise

Create Car Insurance Application withoutSpring

Once its working, introduce Spring

Discuss Other Possibilities

spring and tdd

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