spring整合springmvc
- spring整合springmvc中web.xml配置如下,tomcat在启动过程中会加载web.xml中的内容,ContextLoaderListener实现了tomcat里面的ServletContextListener接口,所以在tomcat容器启动过程通过ContextLoaderListener来进行spring容器的初始化操作,并将classpath:spring/applicationContext-*.xml指定下的spring配置文件加载,该配置文件我只配置了<context:component-scan base-package=“org.com.yp”/>,代表通过扫描org.com.yp包下的类,包含@Component @Controller@Service等注解等类,进行bean注册。
- bean注册是通过AbstractXmlApplicationContext.loadBeanDefinitions该类的方法进行bean定义加载的。
spring中加载bean定义是在org.springframework.context.ConfigurableApplicationContext#refresh方法中的ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory()方法加载bean的,该方法之后会调用org.springframework.context.support.AbstractRefreshableApplicationContext#refreshBeanFactory方法创建bean工厂,并加载的bean定义。
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<?xml version= "1.0" encoding= "UTF-8" ?>
<web-app xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance"
xmlns= "http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http: //java.sun.com/xml/ns/javaee
http: //java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>Archetype Created Web Application</display-name>
<listener>
<listener- class >org.springframework.web.context.ContextLoaderListener</listener- class >
</listener>
<!-- 加载spring容器 -->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring/applicationContext-*.xml</param-value>
</context-param>
<servlet>
<servlet-name>mvc-dispatcher</servlet-name>
<servlet- class >org.springframework.web.servlet.DispatcherServlet</servlet- class >
<!-- 配置springMVC需要加载的配置文件-->
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring/spring-*.xml</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>mvc-dispatcher</servlet-name>
<!-- 默认匹配所有的请求 -->
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
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当tomcat容器启动后,通过路径访问资源时,第一次会调用org.springframework.web.servlet.HttpServletBean#init方法,之后的http请求就不会再方法该方法类;HttpServletBean实现了Servlet接口的规范,所以经过浏览器的请求经过servlet接口初始化执行init方法时,会再从spring容器中去加载springmvc配置中定义的加载类,spring与springmvc是父子容器的关系,下面是HttpServletBean的init方法
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public final void init() throws ServletException {
// Set bean properties from init parameters.
PropertyValues pvs = new ServletConfigPropertyValues(getServletConfig(), this .requiredProperties);
if (!pvs.isEmpty()) {
try {
BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess( this );
ResourceLoader resourceLoader = new ServletContextResourceLoader(getServletContext());
bw.registerCustomEditor(Resource. class , new ResourceEditor(resourceLoader, getEnvironment()));
initBeanWrapper(bw);
bw.setPropertyValues(pvs, true );
}
catch (BeansException ex) {
if (logger.isErrorEnabled()) {
logger.error( "Failed to set bean properties on servlet '" + getServletName() + "'" , ex);
}
throw ex;
}
}
// 最后会调用org.springframework.context.ConfigurableApplicationContext#refresh容器的刷新方法,
// 进行springmvc容器初始化
initServletBean();
}
}
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springboot启动容器
- springboot启动的方式则是先在springboot的org.springframework.boot.SpringApplication#run(java.lang.String…)方法中就初始化了spring的上下文环境(里面包含bean工厂),之后通过org.springframework.boot.SpringApplication#refreshContext方法调用Spring容器中的ConfigurableApplicationContext#refresh方法初始化bean.
- 在spring与springmvc整合的环境中,bean定义的加载是在org.springframework.context.support.AbstractApplicationContext#obtainFreshBeanFactory方法,而springboot中是在
org.springframework.context.support.AbstractApplicationContext#invokeBeanFactoryPostProcessors方法,该方法中通过ConfigurationClassPostProcessor类去加载bean定义,该类实现了BeanDefinitionRegistryPostProcessor接口,这个接口允许对bean定义进行加工处理。
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// spring中的BeanDefinitionRegistryPostProcessor是BeanFactoryPostProcessor的子接口,
// BeanFactoryPostProcessor的作用是在bean的定义信息已经加载但还没有初始化的时候执行方法postProcessBeanFactory()方法,
// 而BeanDefinitionRegistryPostProcessor是在BeanFactoryPostProcessor的前面执行,在源码
// org.springframework.context.support.PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors()方法里面定义了执行顺序
// BeanFactoryPostProcessor是bean工厂的bean属性处理容器,说通俗一些就是可以管理我们的bean工厂内所有的beandefinition(未实例化)数据,可以随心所欲的修改属性。
public void refresh() throws BeansException, IllegalStateException {
synchronized ( this .startupShutdownMonitor) {
prepareRefresh();
//获取告诉子类初始化Bean工厂 将bean加载到缓存中 spring springmvc整合是在这初始化bean的
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
prepareBeanFactory(beanFactory);
try {
postProcessBeanFactory(beanFactory);
// springboot容器启动加载到这时,初始化了下面几个bean name
//0 = "org.springframework.context.annotation.internalConfigurationAnnotationProcessor" =》对应ConfigurationClassPostProcessor类
//1 = "org.springframework.context.annotation.internalAutowiredAnnotationProcessor" =》 AutowiredAnnotationBeanPostProcessor
//2 = "org.springframework.context.annotation.internalCommonAnnotationProcessor" =》 CommonAnnotationBeanPostProcessor
//3 = "org.springframework.context.event.internalEventListenerProcessor" =》 EventListenerMethodProcessor
//4 = "org.springframework.context.event.internalEventListenerFactory" =》 DefaultEventListenerFactory
// 调用我们的bean工厂的后置处理器.加载bean定义(不是实例化),通过ConfigurationClassPostProcessor去加载启动类中的扫描路径
// 然后将路径下到bean加载进来
invokeBeanFactoryPostProcessors(beanFactory);
registerBeanPostProcessors(beanFactory);
initMessageSource();
initApplicationEventMulticaster();
// 这个方法同样也是留个子类实现的springboot也是从这个方法进行启动tomat的.
onRefresh();
registerListeners();
//实例化我们剩余的单实例bean.
finishBeanFactoryInitialization(beanFactory);
// 最后容器刷新 发布刷新事件(Spring cloud也是从这里启动的)
finishRefresh();
}
catch (BeansException ex) {
if (logger.isWarnEnabled()) {
logger.warn( "Exception encountered during context initialization - " +
"cancelling refresh attempt: " + ex);
}
// Destroy already created singletons to avoid dangling resources.
destroyBeans();
// Reset 'active' flag.
cancelRefresh(ex);
// Propagate exception to caller.
throw ex;
}
finally {
// Reset common introspection caches in Spring's core, since we
// might not ever need metadata for singleton beans anymore...
resetCommonCaches();
}
}
}
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原文链接:https://blog.csdn.net/qq_37803406/article/details/116403947