Spring 源码梳理(六) BeanNameAware和BeanFactoryAware

小鱼儿 2022-07-17 16:16 400阅读 0赞

***BeanNameAware和BeanFactoryAware***

**1.BeanNameAware和BeanFactoryAware概念**

BeanNameAware:实现该接口的Bean能够在初始化时知道自己在BeanFactory中对应的名字。

BeanFactoryAware:实现该接口的Bean能够在初始化时知道自己所在的BeanFactory的名字。

**2.继续前面文章的分析，看这一段源码：**

![Center][]

initializeBean方法，前面的文章已经分析过了，上图中的applyBeanPostProcessorsBeforeInitialization也分析了。 这个invokeAwareMethods就是对继承Aware接口的Bean进行初始化，再看下图：

![Center 1][]

也就是说继承BeanNameAware接口的会获得Bean名称，继承BeanFactoryAware接口的会获得BeanFactory名称。

**3.在App.java中继承上述两个接口，并且打印相关信息：**

package com.mycompany.app;
    
    import java.util.HashMap;
    import java.util.Map;
    
    import org.springframework.beans.BeansException;
    import org.springframework.beans.factory.BeanFactory;
    import org.springframework.beans.factory.BeanFactoryAware;
    import org.springframework.beans.factory.BeanNameAware;
    import org.springframework.beans.factory.FactoryBean;
    import org.springframework.beans.factory.InitializingBean;
    
    public class App implements InitializingBean,FactoryBean<Object>,BeanNameAware,BeanFactoryAware
    {
    	private App(){
    		System.out.println("App.App()");
    	}
    	private  String says="App";
        public String getSays() {
    		return says;
    	}
    	public void setSays(String says) {
    		this.says = says;
    	}
    	public void say(){
        	System.out.println("App.app():"+says);
        }
    	
    	/*如在源码中看到的，在getset之后，在BeanPostProcessor的after方法之前执行*/
    	public void setBeanName(String name) {
    		System.out.println("App.setBeanName():"+name);
    	}
    	/*如在源码中看到的，在getset之后，在BeanPostProcessor的after方法之前执行*/
    	public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
    		System.out.println("App.setBeanFactory():"+beanFactory);
    	}
    	/**
    	 * 在构造函数和getset方法之后执行postProcessBeforeInitialization方法
    	 */
    	/*这个方法是InitializingBean在继承InitializingBean接口后，要实现的方法，顾名思义，是在
    	 *属性设置之后进行一些操作*/
    	public void afterPropertiesSet() throws Exception {
    		System.out.println("App.afterPropertiesSet()");
    	}
    	/*这个方法是在Spring配置中通过init-method属性指定为该方法，然后才会执行，在afterPropertiesSet方法之后*/
    	public void initMethod(){
    		System.out.println("App.initMethod()");
    	}
    	/**
    	 *在afterPropertiesSet和initMethod方法之后执行postProcessAfterInitialization方法
    	 */
    	
    	/*FactoryBean测试*/
    	public Object getObject() throws Exception {
    		System.out.println("App.getObject()");
    		Map<String,Object> map = new HashMap<String, Object>();
    		map.put("test", "GetObject");
    		return map;
    	}
    	@SuppressWarnings("rawtypes")
    	public Class<?> getObjectType() {
    		return new HashMap().getClass();
    	}
    	public boolean isSingleton() {
    		return true;
    	}
    }

其他几个文件前面贴过，这里再贴上来：

BeanFactoryPostProcessorApp.java

package com.mycompany.app;
    
    import org.springframework.beans.BeansException;
    import org.springframework.beans.factory.config.BeanDefinition;
    import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
    import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
    
    public class BeanFactoryPostProcessorApp implements BeanFactoryPostProcessor{
    	private BeanFactoryPostProcessorApp() {
    		System.out.println("BeanFactoryPostProcessorApp.BeanFactoryPostProcessorApp()");
    	}
    
    	public void postProcessBeanFactory(
    			ConfigurableListableBeanFactory beanFactory) throws BeansException {
    		BeanDefinition beanDefinition = (BeanDefinition)beanFactory.getBeanDefinition("app");
    		beanDefinition.setAttribute("says", "BeanFactoryPostProcessor");
    		System.out
    				.println("BeanFactoryPostProcessorApp.postProcessBeanFactory(): "+beanDefinition.getAttribute("says"));
    	}
    
    }

BeanPostProcessorApp.java

package com.mycompany.app;
    
    import org.springframework.beans.BeansException;
    import org.springframework.beans.factory.config.BeanPostProcessor;
    
    public class BeanPostProcessorApp implements BeanPostProcessor{
    	
    	/*如果打印结果出现该字符串,证明进行了初始化*/
    	private BeanPostProcessorApp(){
    		System.out.println("BeanPostProcessorApp.BeanPostProcessorApp()");
    	}
    	
    	public Object postProcessBeforeInitialization(Object bean, String beanName)
    			throws BeansException {
    		if(bean instanceof App){
    			((App)bean).setSays("Before:BeanPostProcessorApp");
    			System.out
    					.println("BeanPostProcessorApp.postProcessBeforeInitialization()");
    		}
    		return bean;
    	}
    
    	public Object postProcessAfterInitialization(Object bean, String beanName)
    			throws BeansException {
    		if(bean instanceof App){
    			((App)bean).setSays("After:BeanPostProcessorApp");
    			System.out
    					.println("BeanPostProcessorApp.postProcessAfterInitialization()");
    		}
    		return bean;
    	}
    
    }

SpringBean.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:context="http://www.springframework.org/schema/context"  
        xmlns:mybatis-spring="http://mybatis.org/schema/mybatis-spring"  
        xmlns:tx="http://www.springframework.org/schema/tx" xmlns:jee="http://www.springframework.org/schema/jee"  
        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd  
            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd  
            http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd  
            http://mybatis.org/schema/mybatis-spring http://mybatis.org/schema/mybatis-spring-1.2.xsd  
            http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd">  
       
          
        <bean id="app" class="com.mycompany.app.App" init-method="initMethod"></bean>  
      
      	<bean id="beanPostProcessorApp" class="com.mycompany.app.BeanPostProcessorApp"></bean>
      	
      	<bean id="beanFactoryPostProcessorApp" class="com.mycompany.app.BeanFactoryPostProcessorApp"></bean>
    </beans>

BeanFactoryPostProcessorAppTest.java

package com.mycompany.app;
    
    import java.util.Map;
    
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    public class BeanFactoryPostProcessorAppTest {
    	public static void main(String[] args) {
        	@SuppressWarnings("resource")
    		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("SpringBean.xml"); 
            Map map = (Map)applicationContext.getBean("app");  
            System.out.println("BeanFactoryPostProcessorAppTest.main()："+map.get("test").toString());
    	}
    
    }

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
      <modelVersion>4.0.0</modelVersion>
      <groupId>com.mycompany.app</groupId>
      <artifactId>myapp</artifactId>
      <packaging>jar</packaging>
      <version>1.0-SNAPSHOT</version>
      <name>myapp</name>
      <url>http://maven.apache.org</url>
      
      <properties>
    		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    		<spring.version>4.1.3.RELEASE</spring.version>
      </properties>
      
      <dependencies>
        <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>3.8.1</version>
          <scope>test</scope>
        </dependency>
       	<dependency>
    		<groupId>org.springframework</groupId>
    		<artifactId>spring-core</artifactId>
    		<version>${spring.version}</version>
    	</dependency>
    
    	<dependency>
    		<groupId>org.springframework</groupId>
    		<artifactId>spring-tx</artifactId>
    		<version>${spring.version}</version>
    	</dependency>
    
    	<dependency>
    		<groupId>org.springframework</groupId>
    		<artifactId>spring-web</artifactId>
    		<version>${spring.version}</version>
    	</dependency>
    
    	<dependency>
    		<groupId>org.springframework</groupId>
    		<artifactId>spring-context-support</artifactId>
    		<version>${spring.version}</version>
    	</dependency>
    
    	<dependency>
    		<groupId>org.springframework</groupId>
    		<artifactId>spring-webmvc</artifactId>
    		<version>${spring.version}</version>
    	</dependency>
    
    	<dependency>
    		<groupId>org.springframework</groupId>
    		<artifactId>spring-jdbc</artifactId>
    		<version>${spring.version}</version>
    	</dependency>
      </dependencies>
      
    </project>

然后运行BeanFactoryPostProcessorAppTest.java，结果如下：

![Center 2][]

**4.梳理下执行顺序：**

BeanFactory接口 -> Bean构造函数 -> Bean的GetSet方法 -> Aware接口 -> BeanPostProcessor的Before方法

\-> afterPropertiesSet -> initMethod -> BeanPostProcessor的After方法 -> FactoryBean的getObject方法

[Center]: /images/20220717/a96b7fe372b94423a4b512d37496f03f.png
[Center 1]: /images/20220717/49e19ce4107b4cc3be322ecf73e71a6a.png
[Center 2]: /images/20220717/1e4b3250c4e34354b2f43674cbb3c6d2.png