github原文链接 https://github.com/DespairYoke/java-advance。创作不易，请给个免费的star，已表支持。
初始化
springmvc初始化时，会回调RequestMappingHandlerMapping中的afterPropertiesSet方法。
@Override
public void afterPropertiesSet() {
initHandlerMethods();
}
追踪到initHandlerMethods中
if (beanType != null && isHandler(beanType)) {
detectHandlerMethods(beanName);
}
- isHander(beanType)见名知意，是对beanType类型判断，具体实现代码为
protected boolean isHandler(Class<?> beanType) {
return (AnnotatedElementUtils.hasAnnotation(beanType, Controller.class) ||
AnnotatedElementUtils.hasAnnotation(beanType, RequestMapping.class));
}
最关键的是detectHandlerMethods(beanName)
负责对所有的controller类进行处理
Map<Method, T> methods = MethodIntrospector.selectMethods(userType,
(MethodIntrospector.MetadataLookup<T>) method -> {
return getMappingForMethod(method, userType);
});
- method为方法名，userType为当前处理的类。遍历该类中的所有方法，对方法进行参数路径请求方式等就行处理。
下面看下getMappingForMethod是如何对不同方法进行处理的。
protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {
RequestMappingInfo info = createRequestMappingInfo(method);
if (info != null) {
RequestMappingInfo typeInfo = createRequestMappingInfo(handlerType); //handlerType 是类 这里为了解决类上的@RequestMapping使用
if (typeInfo != null) {
info = typeInfo.combine(info);
}
}
return info;
}
可以看出为每个方法都创建了一个RequestMappingInfo，而RequestMappingInfo正是RequestCondition集合，记录了请路径、参数、方式、头等。可以看下对象内容
private final MyPatternsRequestCondition patternsCondition;
private final MyRequestMethodsRequestCondition methodsCondition;
private final MyParamsRequestCondition paramsCondition;
private final MyHeadersRequestCondition headersCondition;
private final MyConsumesRequestCondition consumesCondition;
private final MyProducesRequestCondition producesCondition;
private final MyRequestConditionHolder customConditionHolder;
获取后的RequestMappingInfo会注册到HandlerMethod中
methods.forEach((method, mapping) -> {
Method invocableMethod = AopUtils.selectInvocableMethod(method, userType);
registerHandlerMethod(handler, invocableMethod, mapping);
});
最终注册到mappingRegistry中
protected void registerHandlerMethod(Object handler, Method method, T mapping) {
this.mappingRegistry.register(mapping, handler, method);
System.out.println("ssss");
}
客户端发起请求
当客户端发起请求后，tomcat的servlet会转发到DispatcherServlet的servce函数回调。经过doDispatch,getHandler,再到AbstractHandlerMapping的getHandler，getHandlerInternal,lookupHandlerMethod
看下lookupHandlerMethod代码
protected HandlerMethod lookupHandlerMethod(String lookupPath, HttpServletRequest request) throws Exception {
List<Match> matches = new ArrayList<>();
List<T> directPathMatches = this.mappingRegistry.getMappingsByUrl(lookupPath);
}
这时，看到了我们初始化时，加载的mappingRegistry，这时就能匹配成功，找到对应的方法。
