马哥高端Go语言百万并发高薪班7期-2022最新完结无密含文档源码 go

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spring MVC源码探究之AbstractHandlerMethodMapping
AbstractHandlerMethodMapping 是什么
解释是这样的。
/**

Abstract base class for {@link HandlerMapping} implementations that define
a mapping between a request and a {@link HandlerMethod}.
*
For each registered handler method, a unique mapping is maintained with
subclasses defining the details of the mapping type {@code }.
@param The mapping for a {@link HandlerMethod} containing the conditions
needed to match the handler method to incoming request.
*/

public abstract class AbstractHandlerMethodMapping extends AbstractHandlerMapping implements InitializingBean
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我的了解为AbstractHandlerMethodMapping为每个注册的handler method，关于每个子类映射类型都维护着其独一的一个映射，就是维护handler method 和URL的关系。主要用于@Controller,@RequestMapping 等注解
AbstractHandlerMethodMapping 完成了InitializingBean接口，InitializingBean是在程序启动的时分执行其独一的afterPropertiesSet()办法，那我们就先看一下启动时分的要做哪些操作。
initHandlerMethods()
/**

在初始化的时分发现 handler methods * Detects handler methods at initialization. */ @Override public void afterPropertiesSet() { initHandlerMethods(); }

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在项目启动时会执行initHandlerMethods办法，它的主要功用是扫描应用上下文，发现并注册handler methods。
/**

Scan beans in the ApplicationContext, detect and register handler methods.
@see #isHandler(Class)
@see #getMappingForMethod(Method, Class)
@see #handlerMethodsInitialized(Map)
*/

protected void initHandlerMethods() {

if (logger.isDebugEnabled()) { logger.debug("Looking for request mappings in application context: " + getApplicationContext()); } // 获取IOC容器中一切bean String[] beanNames = (this.detectHandlerMethodsInAncestorContexts ? BeanFactoryUtils.beanNamesForTypeIncludingAncestors(obtainApplicationContext(), Object.class) : obtainApplicationContext().getBeanNamesForType(Object.class)); for (String beanName : beanNames) { if (!beanName.startsWith(SCOPED_TARGET_NAME_PREFIX)) { Class beanType = null; try { beanType = obtainApplicationContext().getType(beanName); } catch (Throwable ex) { // An unresolvable bean type, probably from a lazy bean - let's ignore it. if (logger.isDebugEnabled()) { logger.debug("Could not resolve target class for bean with name '" + beanName + "'", ex); } } // 判别bean 能否有Controller 注解或者RequestMapping 注解 if (beanType != null && isHandler(beanType)) { detectHandlerMethods(beanName); } } } handlerMethodsInitialized(getHandlerMethods());

}
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isHandler()
AbstractHandlerMethodMapping#isHandler()
RequestMappingHandlerMapping 是目前为止AbstractHandlerMethodMapping的子类中独一完成了isHandler()办法的子类，看下完成
protected boolean isHandler(Class beanType) {

return (AnnotatedElementUtils.hasAnnotation(beanType, Controller.class) || AnnotatedElementUtils.hasAnnotation(beanType, RequestMapping.class)); }

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isHandler()办法在这里的作用就是检查beanType能否有@Controller或@RequestMapping注解，这两个注解经常运用，应该都很熟习了。
detectHandlerMethods()
AbstractHandlerMethodMapping#detectHandlerMethods() 这个办法的作用是从handler中获取handler method并注册
protected void detectHandlerMethods(final Object handler) {

Class handlerType = (handler instanceof String ? obtainApplicationContext().getType((String) handler) : handler.getClass()); if (handlerType != null) { //为给定的类返回用户定义的类:通常只是给定的类，假如是cglib生成的子类，则返回原始的类。 final Class userType = ClassUtils.getUserClass(handlerType); Map methods = MethodIntrospector.selectMethods(userType, (MethodIntrospector.MetadataLookup) method -> { try { // 为处置程序办法提供映射 return getMappingForMethod(method, userType); } catch (Throwable ex) { throw new IllegalStateException("Invalid mapping on handler class [" + userType.getName() + "]: " + method, ex); } }); if (logger.isDebugEnabled()) { logger.debug(methods.size() + " request handler methods found on " + userType + ": " + methods); }// 为查找到的handler method 停止注册 methods.forEach((method, mapping) -> { Method invocableMethod = AopUtils.selectInvocableMethod(method, userType); registerHandlerMethod(handler, invocableMethod, mapping); }); } }

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registerHandlerMethod()
AbstractHandlerMethodMapping#registerHandlerMethod() 的作用是为每个handler method注册它们独一的映射途径，源码如下：
/**