Spring DI with Object Using Setter Injection

We will see below how to inject dependency object through the Setter Injection.

package com.bk.spring.test;

public class StudentBean {

    private int id;
    private String name;
    private String emailId;
    private CourseBean courseBean;

    public int getId() {
        return id;
    }


    public void setId(int id) {
        this.id = id;
    }


    public String getName() {
        return name;
    }


    public void setName(String name) {
        this.name = name;
    }


    public String getEmailId() {
        return emailId;
    }


    public void setEmailId(String emailId) {
        this.emailId = emailId;
    }


    public CourseBean getCourseBean() {
        return courseBean;
    }


    public void setCourseBean(CourseBean courseBean) {
        this.courseBean = courseBean;
    }


    public void getStudentDetails() {
        System.out.println("Id is " + this.id + " \n name is " + name
                + " \n email id is " + emailId +  "\n" + courseBean.getCourseDetails());
    }

}

package com.bk.spring.test;

public class CourseBean {

    private String name;
    private String duration;
    private Double fee;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDuration() {
        return duration;
    }

    public void setDuration(String duration) {
        this.duration = duration;
    }

    public Double getFee() {
        return fee;
    }

    public void setFee(Double fee) {
        this.fee = fee;
    }
       
    public String getCourseDetails(){
        return "Course " + name + " has " + duration + " duration with fee " + fee;
    }

}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
    <bean name="student" class="com.bk.spring.test.StudentBean">
        <property name="id" value="1"></property>
        <property name="name" value="Krishna"></property>
        <property name="emailId" value="Krishna@abc.com"></property>
        <property name="courseBean" ref="courseBean"></property>
    </bean>
    <bean name="courseBean" class="com.bk.spring.test.CourseBean">
        <property name="name" value="Java"></property>
        <property name="duration" value="90Days"></property>
        <property name="fee" value="2018"></property>
       </bean>
   </beans>


package com.bk.spring.test;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;

public class SpringConDITest {

    public static void main(String a[]) {

        Resource res = new ClassPathResource("applicationContext.xml");
        BeanFactory factory = new XmlBeanFactory(res);
        StudentBean bean = (StudentBean) factory.getBean("student");
        bean.getStudentDetails();
       
    }

}
Output:

Id is 1
 name is Krishna
 email id is Krishna@abc.com
Course Java has 90Days duration with fee 2018.0
 

Spring DI with Object Using CI

We will see below how to inject dependency object through the Constructor Injection.

package com.bk.spring.test;

public class CourseBean {

    private String name;
    private String duration;
    private Double fee;

   public CourseBean(String name, String duration, Double fee){
        this.name = name;
        this.duration = duration;
        this.fee = fee;
    }
   
    public String getCourseDetails(){
        return "Course " + name + " has " + duration + " duration with fee " + fee;
    }

}


package com.bk.spring.test;

public class StudentBean {

    private int id;
    private String name;
    private String emailId;
    private CourseBean courseBean;
    private double fee;

    StudentBean() {
        System.out.println("default constructor");
    }

    StudentBean(String name) {
        this.name = name;
    }
   
    StudentBean(int id) {
        this.id = id;
    }

    StudentBean(int id, String name, String emailId, CourseBean courseBean, double fee) {
        this.id = id;
        this.name = name;
        this.emailId = emailId;
        this.courseBean = courseBean;
        this.fee = fee;
    }

    public void getStudentDetails() {
        System.out.println("Id is " + this.id + " \n name is " + name
                + " \n email id is " + emailId +  "\n" + courseBean.getCourseDetails());
    }

}


<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
    <bean name="student" class="com.bk.spring.test.StudentBean">
        <constructor-arg value="001" />
        <constructor-arg value="krishna" />
        <constructor-arg value="Krishna@abc.com" />
        <constructor-arg>
        <ref bean="courseBean"/>
        </constructor-arg>
        <constructor-arg value="2018" />
    </bean>
    <bean name="courseBean" class="com.bk.spring.test.CourseBean">
        <constructor-arg value="Java"/>
        <constructor-arg value="90 Days"/>
        <constructor-arg value="2018"/>
    </bean>
  </beans>

package com.bk.spring.test;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;

public class SpringConDITest {

    public static void main(String a[]) {

        Resource res = new ClassPathResource("applicationContext.xml");
        BeanFactory factory = new XmlBeanFactory(res);
        StudentBean bean = (StudentBean) factory.getBean("student");
        bean.getStudentDetails();
          }

}

Output :
Id is 1
 name is krishna
 email id is Krishna@abc.com
Course Java has 90Days duration with fee 2018.0

Spring CI with Map

We can inject the map values by constructor in spring frame work. We can inject the map as follows.

package com.bk.spring.test;

import java.util.Map;

public class TestBean {

    private String id;
    private String question;
    private Map<String, String> answers;

    public TestBean(String id, String question, Map<String, String> answers) {
        this.id = id;
        this.question = question;
        this.answers = answers;
    }

    public void displayQandA() {
        System.out.println("Question id is");
        System.out.println(id);
        System.out.println("Question is");
        System.out.println(question);
        System.out.println("Answer is ");
        System.out.println(answers);
    }

}


<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
        <bean name="testBean" class="com.bk.spring.test.TestBean">
        <constructor-arg value="00001" />
        <constructor-arg value="What is Spring?"></constructor-arg>
        <constructor-arg>
            <map>
                <entry key="Spring is Enterprise application dev framework" value="Krishna"></entry>
                <entry key="Spring is open source framework" value="Chandu"></entry>
            </map>
        </constructor-arg>
    </bean>
</beans>

package com.bk.spring.test;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;

public class SpringConDITest {

    public static void main(String a[]) {

        Resource res = new ClassPathResource("applicationContext.xml");
        BeanFactory factory = new XmlBeanFactory(res);
               
        TestBean testBean = (TestBean)factory.getBean("testBean");
        testBean.displayQandA();

    }

}


Output:

Question id is
00001
Question is
What is Spring?
Answer is
{Spring is Enterprise application dev framework=Krishna, Spring is open source framework=Chandu}

Spring CI with collections

We can inject the collection values by constructor in spring frame work. We can inject the list as follows.

package com.bk.spring.test;

import java.util.List;

public class EmployeeBean {

    private String id;
    private String name;
    private List<String> projects;
   
    public EmployeeBean(String id, String name, List<String> projects){
        this.id = id;
        this.name = name;
        this.projects = projects;
    }
   
    public void displayEmplyeeDetails(){
        System.out.println("employee details are " + id + " ");
        System.out.println("id is " + id);
        System.out.println("name is " + name);
        System.out.println("projects are " );
        for (String string : projects) {
            System.out.println(string);
        }
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
       <bean name="employeeBean" class="com.bk.spring.test.EmployeeBean">
        <constructor-arg value="0000001" />
        <constructor-arg value="Krishna" />
        <constructor-arg>
            <list>
                <value>Java Project</value>
                <value>J2EE Project</value>
                <value>Spring Project</value>
            </list>
        </constructor-arg>
    </bean>
</beans>


package com.bk.spring.test;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;

public class SpringConDITest {

    public static void main(String a[]) {

        Resource res = new ClassPathResource("applicationContext.xml");
        BeanFactory factory = new XmlBeanFactory(res);
    
        EmployeeBean employeeBean = (EmployeeBean) factory.getBean("employeeBean");
        employeeBean.displayEmplyeeDetails();

    }

}

Setter injection in Spring

Setter injection is one of the approach to inject dependencies in Spring. We can use <property> element of <bean> tag to set the properties as shown below.

package com.bk.spring.test;

public class CourseBean {

    private String name;
    private String duration;
    private Double fee;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDuration() {
        return duration;
    }

    public void setDuration(String duration) {
        this.duration = duration;
    }

    public Double getFee() {
        return fee;
    }

    public void setFee(Double fee) {
        this.fee = fee;
    }
   
    public void getCourseDetails(){
        System.out.println("Course " + name + " has " + duration + " duration with fee " + fee);
    }

}

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" xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
      <bean name="courseBean" class="com.bk.spring.test.CourseBean">
    <property name="name" value="Java"></property>
    <property name="duration" value="90Days"></property>
    <property name="fee" value="2018"></property>
    </bean>
</beans>

Main test class:

package com.bk.spring.test;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;

public class SpringConDITest {

    public static void main(String a[]) {

        Resource res = new ClassPathResource("applicationContext.xml");
        BeanFactory factory = new XmlBeanFactory(res);  
        CourseBean courseBean = (CourseBean) factory.getBean("courseBean");
        courseBean.getCourseDetails();

    }

}

Output : Course Java has 90Days duration with fee 2018.0