1:看Dispatcher
Servlet的初始化策略
protected void initStrategies(ApplicationContext context) {
initMultipartResolver(context);
initLocaleResolver(context);
initThemeResolver(context);
//初始化处理器映射关系,即用户请求与程序处理的对应关系
initHandlerMappings(context);
initHandlerAdapters(context);
initHandlerExceptionResolvers(context);
initRequestToViewNameTranslator(context);
initViewResolvers(context);
}
//initHandlerMappings默认会先探测ApplicationContext对象中已经设定好的任何HandlerMapping对象,如果有就使用定义好的,如果没有,调用方法getDefaultStrategies,使用默认配置,DisptatchServlet.properties文件中默认的org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping,org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping两个HandlerMapping对象。
2:看下DefaultAnnotationHandlerMapping类层次关系,BeanNameUrlHandlerMapping类层次是一样的
//类层次,凑合看
DefaultAnnotationHandlerMapping
AbstractDetectingUrlHandlerMapping
AbstractUrlHandlerMapping
AbstractHandlerMapping
extends WebApplicationObjectSupport implements HandlerMapping, Ordered
//这里继承了WebApplicationObjectSupport对象,关于这个对象:Convenient superclass for application objects running in a WebApplicationContext.
WebApplicationObjectSupport
extends ApplicationObjectSupport implements ServletContextAware
implements ApplicationContextAware
3:抽象类ApplicationObjectSupport实现了ApplicationContextAware,spring容器的后置处理器会调用setApplicationContext方法,执行顺序:
//ApplicationObjectSupport中的setApplicationContext方法执行
public final void setApplicationContext(ApplicationContext context) throws BeansException {
if (context == null && !isContextRequired()) {
// Reset internal context state.
this.applicationContext = null;
this.messageSourceAccessor = null;
}
else if (this.applicationContext == null) {
// Initialize with passed-in context.
if (!requiredContextClass().isInstance(context)) {
throw new ApplicationContextException(
"Invalid application context: needs to be of type [" + requiredContextClass().getName() + "]");
}
this.applicationContext = context;
this.messageSourceAccessor = new MessageSourceAccessor(context);
//这里会先执行子类WebApplicationObjectSupport的initApplicationContext方法,然后到ApplicationObjectSupport自己的init方法,ApplicationObjectSupport本身的该方法没有任何处理,只是调用了一个空的方法initApplicationContext(),这个无参的重载方法被当作一个钩子供子类方法来实现。
initApplicationContext(context);
}
else {
// Ignore reinitialization if same context passed in.
if (this.applicationContext != context) {
throw new ApplicationContextException(
"Cannot reinitialize with different application context: current one is [" +
this.applicationContext + "], passed-in one is [" + context + "]");
}
}
}
4:initApplicationContext()执行,spring默认的两个处理器映射类都继承自AbstractDetectingUrlHandlerMapping抽象类,而且类初始化将被执行的initApplicationContext方法也在这个类得到了实现
//AbstractDetectingUrlHandlerMapping中的initApplicationContext方法
public void initApplicationContext() throws ApplicationContextException {
//先执行超类的initApplicationContext方法,这个超类的方法完成的任务就是对定义好的拦截器改装并放入到adaptedInterceptors数组中供以后使用
super.initApplicationContext();
//请求与处理器映射的关键方法
detectHandlers();
}
5:detectHandlers()执行
protected void detectHandlers() throws BeansException {
if (logger.isDebugEnabled()) {
logger.debug("Looking for URL mappings in application context: " + getApplicationContext());
}
//默认会取得上下文中的所有的对象的beanname。
String[] beanNames = (this.detectHandlersInAncestorContexts ?
BeanFactoryUtils.beanNamesForTypeIncludingAncestors(getApplicationContext(), Object.class) :
getApplicationContext().getBeanNamesForType(Object.class));
// Take any bean name that we can determine URLs for.
for (int i = 0; i < beanNames.length; i++) {
String beanName = beanNames[i];
//abstract方法,在子类中实现,即找到符合要求的映射url
String[] urls = determineUrlsForHandler(beanName);
if (!ObjectUtils.isEmpty(urls)) {
// URL paths found: Let's consider it a handler.
//注册处理器,即添加一些映射关系到handlerMap中,一个LinkedHashMap
registerHandler(urls, beanName);
}
else {
if (logger.isDebugEnabled()) {
logger.debug("Rejected bean name '" + beanNames[i] + "': no URL paths identified");
}
}
}
}
6:determineUrlsForHandler方法执行,DefaultAnnotationHandlerMapping为
例子
不贴了,主要就是挨个对象查看,DefaultAnnotationHandlerMapping类就是查看定义的RequestMapping注解,然后把符合要求的urls返回。