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The Spring framework provides developers with a wealth of extension points, one of which is the callback interface in the Bean life cycle. This article will focus on introducing an important interface
BeanFactoryAware
, discuss its function, usage, and application scenarios in actual development.
1 Introduction
In Spring, BeanFactoryAware interface is a callback interface that provides a method for setting up a Bean factory. When a Bean implements the BeanFactoryAware interface, after the Bean instance is instantiated, the Spring container will call the setBeanFactory method and pass the factory where the Bean is located as a parameter Pass it in.
The source code is as follows
2. Function
BeanFactoryAware is mainly used to obtain a reference to the factory (BeanFactory) that loads the current Bean, so that the Bean can obtain information about its own factory at runtime.
3. Use
To make a Bean implement the BeanFactoryAware interface, you need to follow the following steps
3.1 Create and implement the interface
package org.example.cheney;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
public class DemoBean implements BeanFactoryAware {
@Override
public void setBeanFactory(BeanFactory beanFactory) {
System.out.println("【BeanFactoryAware】Bean 的工厂是：" + beanFactory);
}
}
3.2 Configure Bean information
xmlCopy code<bean id="myBean" class="com.example.MyBean"/>
3.3 Create startup class
package org.example.cheney;
import org.springframework.context.support.AbstractXmlApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class App {
public static void main(String[] args) {
String location = "applicationContext.xml";
try (AbstractXmlApplicationContext context = new ClassPathXmlApplicationContext(location)) {
System.out.println("End.");
}
}
}
3.4 Startup
Output result:
4. Application scenarios
BeanFactoryAwareInterfaces are usually used in the following scenarios:
-
Get the Bean factory reference:
When a Bean needs to obtain a reference to its own factory at runtime in order to perform some factory-related operations
-
Dynamically load other beans:
Sometimes other beans need to be loaded dynamically, and the factory reference required to load is the factory that loads the bean.
Summarize
The Spring framework provides developers with a wealth of extension points, one of which is the callback interface in the Bean life cycle. The BeanFactoryAware interface provides developers with a simple and useful way to obtain a reference to the factory where a Bean is located. By implementing this interface, a Bean can obtain a reference to its own factory during the initialization phase, thereby handling some factory-related logic more flexibly.