Spring BeanFactory Example
July 08, 2022
BeanFactory.
1. The
BeanFactory is the root interface for accessing a Spring bean container.
2. Normally a
BeanFactory will load bean definitions stored in a configuration source and can configure them.
3. Bean factory implementations should support the standard bean lifecycle interfaces as far as possible.
4. Find some implementation classes of
BeanFactory interface.
ClassPathXmlApplicationContext
ClassPathXmlApplicationContext
FileSystemXmlApplicationContext
ResourceAdapterApplicationContext
XmlWebApplicationContext
5. Find the methods of
BeanFactory interface.
getBean : Returns bean instance.
containsBean : Returns boolean. It checks if this bean factory contains a bean definition with given name.
getBeanProvider : Returns a provider for the specified bean.
getType : Determines the type of the bean.
isPrototype : Is this bean a prototype.
isSingleton : Is this bean a singleton.
isTypeMatch : Checks whether the bean with the given name matches the specified type.
getBean() Method
ThegetBean() is a BeanFactory method that returns the bean instance. It allows following arguments.
1.
<T> T getBean(Class<T> requiredType) throws BeansException
Parameters: The requiredType is type the bean must match; can be an interface or superclass.
Returns: It returns an instance of the single bean matching the required type.
Throws: If the bean cannot be created, it throws
BeansException.
2.
<T> T getBean(Class<T> requiredType, Object... args) throws BeansException
The requiredType is type the bean must match; can be an interface or superclass.
The args are the arguments to use when creating a bean instance using explicit arguments.
3.
Object getBean(String name) throws BeansException
The name is the name of the bean to retrieve.
4.
<T> T getBean(String name, Class<T> requiredType) throws BeansException
Parameters:
The name is the name of the bean to retrieve.
The requiredType is type the bean must match; can be an interface or superclass.
5.
Object getBean(String name, Object... args) throws BeansException
The name is the name of the bean to retrieve.
The args are the arguments to use when creating a bean instance using explicit arguments.
Example-1
Here we are usingClassPathXmlApplicationContext class that implements BeanFactory interface.
SpringDemo.java
package com.concretepage;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class SpringDemo {
public static void main(String[] args) {
BeanFactory beanFactory = new ClassPathXmlApplicationContext("app-config.xml");
Student student = (Student)beanFactory.getBean("student");
System.out.println(student.getName());
System.out.println(student.getAge());
}
}
package com.concretepage;
public class Student {
private String name;
private int age;
-----
}
<?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="student" class="com.concretepage.Student">
<property name="name" value="Mohan" />
<property name="age" value="25" />
</bean>
</beans>
Mohan 25
Example-2
Here we are usingGenericXmlApplicationContext class that implements BeanFactory interface.
SpringDemo.java
package com.concretepage;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.context.support.GenericXmlApplicationContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
public class SpringDemo {
public static void main(String[] args) {
Resource resource = new ClassPathResource("app-config.xml");
BeanFactory beanFactory = new GenericXmlApplicationContext(resource);
Student student = (Student)beanFactory.getBean("student");
System.out.println(student.getName());
System.out.println(student.getAge());
}
}
