Java Tips By Gaurav: Spring Collection injection or Wiring

Collection Wiring in Spring

Spring Framework provides the support for the Java Collections. It provides support for list, set, map and props java elements. We can use java collection elements by passing direct values of the collection and also by passing a reference of a bean as one of the collection elements.

The Supported Java collection elements are as below:-

<list>:-> It helps in injecting a list of values, as we know list allows duplicates.

<set>:-> It helps in injecting a set of values and as we know set does not allow duplicates.

<map>:-> It can be used to inject a bunch of key-value pairs where key and value can be of any object.

<props>:- > It can be used to inject a bunch of key-value pairs where the key and value are Strings.

How to use List Collection Injection or Wiring in Spring?

List Collection Wiring in Spring

Example of Spring List property or List Collection injection in spring.

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 List injection or wiring:-

Create a java project in eclipse.

Create a package in the src folder with the name as com.spring.gaurav.collection.list.use.example.

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

Create an XML file and name it as collection-list-use-in-spring-framework.xml and place this file in the classpath outside the src folder.

Execute the ListCollectionUseInSpringFrameworkClient.java by selecting the option Run as Java Application.

SaarcNations.java

package com.spring.gaurav.collection.list.use.example;

public class SaarcNations {

private String nationName;

private String nationCapital;

public String getNationName() {

return nationName;

}

public void setNationName(String nationName) {

this.nationName = nationName;

}

public String getNationCapital() {

return nationCapital;

}

public void setNationCapital(String nationCapital) {

this.nationCapital = nationCapital;

}

AsianCountries.java



	package com.spring.gaurav.collection.list.use.example; import java.util.List; public class AsianCountries { private List<SaarcNations> nationList; public List<SaarcNations> getNationList() { return nationList; } public void setNationList(List<SaarcNations> nationList) { this.nationList = nationList; } }

collection-list-use-in-spring-framework.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="asianCountriesBeanId"

class="com.spring.gaurav.collection.list.use.example.AsianCountries">

<!-- We can add values in the list in the below two formats, first by

directly adding the bean or second by adding the referenced bean -->

<list>

<bean class="com.spring.gaurav.collection.list.use.example.SaarcNations">

<property name="nationName"

value="INDIA(REPUBLIC OF INDIA (BHARAT GANRAJYA))" />

<property name="nationCapital" value="NEW DELHI" />

</bean>

<ref bean="saarcNationBeanId1" />

</list>

</property>

</bean>

<bean id="saarcNationBeanId1"