Spring源码分析-IOC之Aware

Aware:已感知的，意识到的，所以这些接口从字面意思应该是能感知到所有

Aware

前面的含义,Spring中提供了一些Aware相关接口,比如BeanNameAware,BeanFactoryAware,ApplicationContextAware等,下面我们来看下BeanNameAware,BeanNameAware就是将name注入实例,我们来看下具体的应用:

[code]package com.ck.bean;

import java.io.Serializable;

import org.springframework.beans.factory.BeanNameAware;

public class Person implements BeanNameAware, Serializable{

private static final long serialVersionUID = 1L;

private String name;

@Override
public void setBeanName(String name) {
this.name = name;
}

public String getName() {
return name;
}

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

}

看下配置文件:

[code]<?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:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.1.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.1.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.1.xsd">

<bean id="person" class="com.ck.bean.Person"/>
</beans>

看下测试代码:

[code]package com.ck.ioc;

import org.junit.Test;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;

import com.ck.bean.Person;

public class IocTest {
@Test
public void test() {
ConfigurableApplicationContext ctx = new FileSystemXmlApplicationContext( "src/main/resources/applicationContext.xml");
Person person = ctx.getBean(Person.class);
System.out.println(person.getName());
}

}

我们看下测试结果:

[code]四月 04, 2019 8:31:16 下午 org.springframework.context.support.FileSystemXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.FileSystemXmlApplicationContext@3c679bde: startup date [Thu Apr 04 20:31:16 CST 2019]; root of context hierarchy
四月 04, 2019 8:31:17 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from file [X:\CK\stsws\springWeb\src\main\resources\applicationContext.xml]
person

我们看到实现了BeanNameAware的接口,最终在实例中获得了在Spring容器中name,spring中的其他aware与BeanNameAware打通小异,各位可以尝试下,我们来看下aware在Spring中的实现原理,我们根据前面介绍的 Spring源码分析-IOC之InitializingBean代码继续往下走:

AbstractAutowireCapableBeanFactory中的initializaBean:

[code]protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {
if (System.getSecurityManager() != null) {
AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
invokeAwareMethods(beanName, bean);
return null;
}
}, getAccessControlContext());
}
else {
//注意此入口
invokeAwareMethods(beanName, bean);
}

Object wrappedBean = bean;
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
}

try {
invokeInitMethods(beanName, wrappedBean, mbd);
}
catch (Throwable ex) {
throw new BeanCreationException(
(mbd != null ? mbd.getResourceDescription() : null),
beanName, "Invocation of init method failed", ex);
}

if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
}
return wrappedBean;
}

//此处我们可以看到Aware实现的地方
private void invokeAwareMethods(final String beanName, final Object bean) {
if (bean instanceof Aware) {
if (bean instanceof BeanNameAware) {
((BeanNameAware) bean).setBeanName(beanName);
}
if (bean instanceof BeanClassLoaderAware) {
((BeanClassLoaderAware) bean).setBeanClassLoader(getBeanClassLoader());
}
if (bean instanceof BeanFactoryAware) {
((BeanFactoryAware) bean).setBeanFactory(AbstractAutowireCapableBeanFactory.this);
}
}
}

通过代码我们可以一目了然的看到Aware的应用以及在Spring中的应用,这些过程都是在Spring容器实例化bean的地方实现的.