Spring启动原理和可扩展设计分析( 二 ) _Spring

web.xml 里的context-param找contextClass
没有的话就加载默认：spring jar里ContextLoader.properties写的XmlWebApplicationContext

web.mxl + DispatcherServlet
<servlet> <servlet-name>springMvc</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class></servlet>DispatcherServlet基于Servlet生命周期会在JAVAx.servlet.GenericServlet.init()初始化spring容器
springboot
DispatcherServletAutoConfiguration
@Bean(name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME) public DispatcherServlet dispatcherServlet() { DispatcherServlet dispatcherServlet = new DispatcherServlet(); dispatcherServlet.setDispatchOptionsRequest( this.webMvcProperties.isDispatchOptionsRequest()); dispatcherServlet.setDispatchTraceRequest( this.webMvcProperties.isDispatchTraceRequest()); dispatcherServlet.setThrowExceptionIfNoHandlerFound( this.webMvcProperties.isThrowExceptionIfNoHandlerFound()); return dispatcherServlet; }Spring MVC原理接着上面的web原理
Dispatcher
Dispatcher是一个Servlet ，是spring web的入口，来看下spring的dispatcher如何处理请求

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spring mvc
Spring MVC的入口是Controller ，那么解析Controller的东西自然就是SpringMVC的入口了。
这个入口就是：

RequestMappingHandlerMapping

这个东西继承了3个Aware

ApplicationAware（Spring web）
ServletContextAware （Spring web）
EmbeddedValueResolverAware （Spring context）

是不是很熟悉！

通过Aware ， Spring mvc就这么起来了！并且能够自定义解析各种注解

RequestMappingHandlerMapping
内部维护一个Map<T, HandlerMethod> handlerMethods ， T就是Controller的类
public class RequestMappingHandlerMapping extends RequestMappingInfoHandlerMapping implements MatchableHandlerMapping, EmbeddedValueResolverAware { /** 1. 初始化 */ public void afterPropertiesSet() { initHandlerMethods(); } /** 2. 扫描所有Object的bean ，扫描Controller、RequestMapping 3. 扫描每个controller的web请求方法，写入到handlerMethods里，以后处理请求时用来对应查找 */protected void initHandlerMethods() {String[] beanNames = (this.detectHandlerMethodsInAncestorContexts ? BeanFactoryUtils.beanNamesForTypeIncludingAncestors(getApplicationContext(), Object.class) : getApplicationContext().getBeanNamesForType(Object.class)); for (String beanName : beanNames) { if (!beanName.startsWith(SCOPED_TARGET_NAME_PREFIX) && isHandler(getApplicationContext().getType(beanName))){ //查找web请求方法 detectHandlerMethods(beanName); } } handlerMethodsInitialized(getHandlerMethods()); } @Override protected boolean isHandler(Class<?> beanType) { return ((AnnotationUtils.findAnnotation(beanType, Controller.class) != null) || (AnnotationUtils.findAnnotation(beanType, RequestMapping.class) != null)); } /** 4. 处理web请求时负责找到对应的处理方法 */ @Override public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception { Object handler = getHandlerInternal(request); if (handler == null) { handler = getDefaultHandler(); } if (handler == null) { return null; } // Bean name or resolved handler? if (handler instanceof String) { String handlerName = (String) handler; handler = getApplicationContext().getBean(handlerName); } /** 组装HandlerExecutionChain ，里面主要包括处理列表： List<HandlerInterceptor> interceptorList; */ return getHandlerExecutionChain(handler, request); }}
【Spring启动原理和可扩展设计分析】