Setter Injection in Spring

                                                 Setter Dependency Injection

This post will show how to use Setter dependency injection in Spring IOC. As in the earlier post I already mentioned about the dependency injection and its types. Please refer the below link for more details:-

http://www.javatechtipssharedbygaurav.com/2013/05/spring-basic-interview-questions-part-1.html

 

In case of setter dependency injection, container calls the setter methods on the bean class after executing a factory method or no-argument constructor for the instantiation of our beans or spring container (IOC container) will inject the dependencies for using the setter methods in a bean class. This is more preferable dependency injection as compare to constructor dependency injection.

Example of Setter Dependency injection:-

System Requirements:-

• Eclipse Editor or any other.

• JDK 1.5 or higher(I am using jdk 1.7.0_03)

• Spring jars.

Required Jars are:-

spring-core.jar
spring-2.5.jar
spring-beans.jar
spring-context.jar
commons-logging.jar
dom4j-1.4.jar
antlr.jar
log4j.jar

Steps for creating Eclipse java project for implementing setter dependency injection:-

• Create a java project in eclipse and name it as SpringSetterInjectionImplementation.

• Create a package in the src folder with the name as com.spring.gauarv.setterinjection.example.

• Create the below files in this package and place the corresponding code in those files.

• Create an XML file and name it as setterinjection-beans.xml and place this file in the classpath outside the src folder.

• Execute the SetterInjectionClient.java by selecting the option Run as Java Application.

CreateProject.java

package com.spring.gauarv.setterinjection.example;

public class CreateProject {
    public CreateProject() {
        System.out.println("INSIDE CREATEPROJECT CLASS CONSTRUCTOR");
    }

    public void createJavaProject() {
        System.out.println("INSIDE CREATEJAVAPROJECT() METHOD");
    }
}

EclipseTool.java

package com.spring.gauarv.setterinjection.example;

public class EclipseTool {
    private CreateProject createProject;

    /**
     * @return the createProject
     */
    public CreateProject getCreateProject() {
        return createProject;
    }

    /**
     * @param createProject
     *            the createProject to set
     */
    public void setCreateProject(CreateProject createProject) {
        this.createProject = createProject;
    }

    public void javaProjectCreation() {
        createProject.createJavaProject();
    }
}

setterinjection-beans.xml

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">


    <bean id="eclipseTool" class="com.spring.gauarv.setterinjection.example.EclipseTool">
        <property name="createProject">
            <bean id="createProject"
                class="com.spring.gauarv.setterinjection.example.CreateProject" />
        </property>
    </bean>
</beans>

SetterInjectionClient.java

package com.spring.gauarv.setterinjection.example;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SetterInjectionClient {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext(
                "setterinjection-beans.xml");

        EclipseTool eclipseTool = (EclipseTool) context.getBean("eclipseTool");

        eclipseTool.javaProjectCreation();
    }
}

Project structure :-

Result:-

log4j:WARN No appenders could be found for logger (org.springframework.context.support.ClassPathXmlApplicationContext).
log4j:WARN Please initialize the log4j system properly.
INSIDE CREATEPROJECT CLASS CONSTRUCTOR
INSIDE CREATEJAVAPROJECT() METHOD

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