一、常见的初始化方式

spring常见的初始化方式有如下几种：

1. main函数里使用ClassPathXmlApplicationContext

public static void main(String[] args) { ClassPathXmlApplicationContext classPathXmlApplicationContext = new ClassPathXmlApplicationContext("classpath*:/spring/test/appcontext-dependencies.xml"); Thread.currentThread().join(); }

2. web.xml通过ContextLoaderListener

contextConfigLocation

classpath:spring/test/appcontext-dependencies.xml

org.springframework.web.context.ContextLoaderListener

3. web.xml通过DispatcherServlet

springDispatcher

org.springframework.web.servlet.DispatcherServlet

contextConfigLocation

classpath\*:config/spring/common/appcontext-\*.xml, classpath\*:config/spring/local/appcontext-\*.xml

springDispatcher

/study/\*

4. spring-test通过SpringJUnit4ClassRunner

@RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations = {"classpath*:/spring/test/appcontext-dependencies.xml"})

5. spring4.x通过groovy dsl

import org.hibernate.validator.HibernateValidator import org.springframework.context.support.ReloadableResourceBundleMessageSource import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean

beans { xmlns context: "http://www.springframework.org/schema/context" xmlns mvc: "http://www.springframework.org/schema/mvc"

context.'component-scan'('base-package': "com.chenxiaojie.spring4")
mvc.'annotation-driven'('validator': "validator")

validator(LocalValidatorFactoryBean) {
    providerClass = HibernateValidator.class
    validationMessageSource = ref("messageSource")
}

}

6. spring4.x通过全注解(http://jinnianshilongnian.iteye.com/blog/1991830)

@Configuration @EnableWebMvc @ComponentScan(basePackages = "com.chenxiaojie.spring4") public class MvcConfiguration extends WebMvcConfigurationSupport { @Override protected Validator getValidator() { LocalValidatorFactoryBean localValidatorFactoryBean = new LocalValidatorFactoryBean(); localValidatorFactoryBean.setProviderClass(HibernateValidator.class); localValidatorFactoryBean.setValidationMessageSource(messageSource()); return localValidatorFactoryBean; } }

二、初始化流程

无论是上方的哪一种初始化方式最后context初始化代码都是下方的refresh方法，这是典型的模板方法设计模式。

AbstractApplicationContext：

public void refresh() throws BeansException, IllegalStateException {

// 同步块决定了spring的初始化一定是单线程的(spring作为bean容器默认只初始化一次, 多线程提高初始化速度并没有什么意义) synchronized (this.startupShutdownMonitor) {

// 预准备refresh, 检查environment参数是否合理 prepareRefresh();

  // 构造beanFactory, 里面包含所有beanDefinition加载, 主要是解析xml和注解
  // 参考AbstractRefreshableApplicationContext->refreshBeanFactory->loadBeanDefinitions方法
  // 参考AbstractBeanDefinitionReader->loadBeanDefinitions(String location, Set<Resource> actualResources)

// 参考XmlBeanDefinitionReader->loadBeanDefinitions(EncodedResource encodedResource) // 参考DefaultBeanDefinitionDocumentReader->doRegisterBeanDefinitions(Element root) // 参考ContextNamespaceHandler->ComponentScanBeanDefinitionParser->parse->ClassPathBeanDefinitionScanner->doScan // 参考ClassPathScanningCandidateComponentProvider->findCandidateComponents(String basePackage) ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

  // 预准备beanFactory, 设置基本环境变量
  prepareBeanFactory(beanFactory);

  try {
     // 默认为空实现
     postProcessBeanFactory(beanFactory);

     // 添加实现了PriorityOrdered优先级极高的处理器, 这个环节只走半生命周期, 因为在new的时候postProcessors还未初始化完毕
     // org.springframework.context.annotation.internalConfigurationAnnotationProcessor
     invokeBeanFactoryPostProcessors(beanFactory);

     // 添加实现了Ordered的处理器,

// org.springframework.context.annotation.internalAutowiredAnnotationProcessor // org.springframework.context.annotation.internalRequiredAnnotationProcessor // org.springframework.context.annotation.internalCommonAnnotationProcessor // org.springframework.aop.config.internalAutoProxyCreator // org.springframework.context.annotation.ConfigurationClassPostProcessor.importAwareProcessor registerBeanPostProcessors(beanFactory);

     // 初始化消息
     initMessageSource();

     // 初始化事件处理器
     initApplicationEventMulticaster();

     // 默认空实现
     onRefresh();

     // 注册所有的spring监听器
     registerListeners();

     // 实现化所有业务相关的单例bean
     finishBeanFactoryInitialization(beanFactory);

     // 执行Lifecycle/事件通知等事务
     finishRefresh();
  }

  catch (BeansException ex) {
     // 销毁所有bean
     destroyBeans();

     cancelRefresh(ex);

     throw ex;
  }

} }

结构图

Spring核心源码