IOC (Inversion Of Control)/ DI (Dependency Injection) - Constructor Injection

Example Code of Constructor Injection - You need to create three files beans.xml, User.java and the main class Main.java Then run the class Main.java . You need spring.jar file in your classpath .

beans.xml

<?xml version="1.0" encoding="UTF-8"?>
<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.xsd">

<bean id="user" class="sycorax.sinjection.User" >
<constructor-arg index="0" type="java.lang.String" value="sycorax"/>
<constructor-arg index="1" type="java.lang.String" value="kolkata"/>
<constructor-arg index="2" type="java.lang.String" value="info@sycorax.co.in"/>
</bean>

</beans>

User.java

package sycorax.sinjection;

/**
*
* @author sycorax.co.in
*/
public class User {

private String name;
private int addr;
private String email;

public User(String name, String addr, String email){
this.name = name;
this.addr = addr;
this.email = email;
}

public String getName() {
return name;
}

public int getAddr() {
return addr;
}

public String getEmail() {
return email;
}

public String toString() {
return "Name :"+name + " Address: " + addr + " Email: " + email;
}
}

Main.java

package springinjection;

/**
*
* @author sycorax.co.in
*/
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main2 {

public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
User user = (User)context.getBean("user");
System.out.println(user);
}

}