Spring Bean Autowire by byName

Practically bean dependencies are explicitly set in bean configuration files and it is really is a good practice to follow. But Spring is capable of automatically resolving dependencies at runtime. This automatic resolution of bean dependencies is also called autowiring. This type of bean dependencies can also be referred to as collaborating beans or just as collaborators.

There are 5 different types of autowiring modes which are ‘no’, ‘byName’, ‘byType’, ‘constructor’, and ‘autodetect’. In this post, I am taking down ‘byName‘ mode.

Autowiring by name allows a property to be autowired such that it will inspect the container and look for a bean named exactly the same as the property which needs to be autowired. For example, if you have a bean definition which is set to autowire by name, and it contains a “departmentBean” property (i.e. it has a setDepartmentBean(..) method), container will look for a bean definition named departmentBean, and if found, use it to set the property.

Sections in this post:

Bean definitions
Autowire dependency using autowire="byName"
Test the dependency

Bean definitions

A typical bean configuration file (e.g. applicationContext.xml) will look like this:

<?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:context="http://www.springframework.org/schema/context"

xsi:schemaLocation="http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

http://www.springframework.org/schema/context

http://www.springframework.org/schema/context/spring-context-3.0.xsd">

<context:component-scan base-package="com.howtodoinjava" />

<bean id="employee" class="com.howtodoinjava.demo.beans.EmployeeBean" autowire="byName">

<property name="fullName" value="Lokesh Gupta"/>

</bean>

<bean id="departmentBean" class="com.howtodoinjava.demo.beans.DepartmentBean" >

<property name="name" value="Human Resource" />

</bean>

</beans>

Autowire dependency using autowire=”byName”

In above configuration, I have enabled the autowiring by name for ’employee’ bean. It has been done using:

autowire="byName"

Let’s see the code.

package com.howtodoinjava.demo.beans;

public class EmployeeBean

{

private String fullName;

private DepartmentBean departmentBean;

public DepartmentBean getDepartmentBean() {

return departmentBean;

}

public void setDepartmentBean(DepartmentBean departmentBean) {

this.departmentBean = departmentBean;

}

public String getFullName() {

return fullName;

}

public void setFullName(String fullName) {

this.fullName = fullName;

}

And DepartmentBean looks like this which has been set:

package com.howtodoinjava.demo.beans;

public class DepartmentBean {

private String name;

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

Test the dependency

To test that bean has been set properly, run following code:

package com.howtodoinjava.demo;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.howtodoinjava.demo.beans.EmployeeBean;

public class TestAutowire {

public static void main(String[] args) {

ApplicationContext context =

new ClassPathXmlApplicationContext(new String[] {"application-context.xml"});

EmployeeBean employee = (EmployeeBean)context.getBean("employee");

System.out.println(employee.getFullName());

System.out.println(employee.getDepartmentBean().getName());

}

Output:

Lokesh Gupta

Human Resource

Clearly, dependency was injected by name successfully.

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Spring Bean Autowire by byName

Spring Bean Autowire by byName

Bean definitions

Autowire dependency using autowire=”byName”

Test the dependency

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