上一篇了解了springmvc 根据http的请求匹配到对应的handler来处理请求。那用来做比较的handler那里来的呢。这就是本文的内容
这个得从springmvc的配置<mvc:annotation-driven/>
开始。
这个标签的解释处理类是:MvcNamespaceHandler
public class MvcNamespaceHandler extends NamespaceHandlerSupport {
@Override
public void init() {
registerBeanDefinitionParser("annotation-driven", new AnnotationDrivenBeanDefinitionParser());
registerBeanDefinitionParser("default-servlet-handler", new DefaultServletHandlerBeanDefinitionParser());
registerBeanDefinitionParser("interceptors", new InterceptorsBeanDefinitionParser());
registerBeanDefinitionParser("resources", new ResourcesBeanDefinitionParser());
registerBeanDefinitionParser("view-controller", new ViewControllerBeanDefinitionParser());
registerBeanDefinitionParser("redirect-view-controller", new ViewControllerBeanDefinitionParser());
registerBeanDefinitionParser("status-controller", new ViewControllerBeanDefinitionParser());
registerBeanDefinitionParser("view-resolvers", new ViewResolversBeanDefinitionParser());
registerBeanDefinitionParser("tiles-configurer", new TilesConfigurerBeanDefinitionParser());
registerBeanDefinitionParser("freemarker-configurer", new FreeMarkerConfigurerBeanDefinitionParser());
registerBeanDefinitionParser("groovy-configurer", new GroovyMarkupConfigurerBeanDefinitionParser());
registerBeanDefinitionParser("script-template-configurer", new ScriptTemplateConfigurerBeanDefinitionParser());
registerBeanDefinitionParser("cors", new CorsBeanDefinitionParser());
}
}
AnnotationDrivenBeanDefinitionParser 类
@Override
public BeanDefinition parse(Element element, ParserContext parserContext) {
//省略
RootBeanDefinition handlerMappingDef = new RootBeanDefinition(RequestMappingHandlerMapping.class);
RootBeanDefinition handlerAdapterDef = new RootBeanDefinition(RequestMappingHandlerAdapter.class);
RootBeanDefinition bindingDef = new RootBeanDefinition(ConfigurableWebBindingInitializer.class);
RootBeanDefinition exceptionHandlerExceptionResolver = new RootBeanDefinition(ExceptionHandlerExceptionResolver.class);
parserContext.registerComponent(new BeanComponentDefinition(handlerMappingDef, HANDLER_MAPPING_BEAN_NAME));
parserContext.registerComponent(new BeanComponentDefinition(handlerAdapterDef, HANDLER_ADAPTER_BEAN_NAME));
// Ensure BeanNameUrlHandlerMapping (SPR-8289) and default HandlerAdapters are not "turned off"
MvcNamespaceUtils.registerDefaultComponents(parserContext, source);
parserContext.popAndRegisterContainingComponent();
return null;
}
public static void registerDefaultComponents(ParserContext parserContext, Object source) {
registerBeanNameUrlHandlerMapping(parserContext, source);
registerHttpRequestHandlerAdapter(parserContext, source);
registerSimpleControllerHandlerAdapter(parserContext, source);
}
至此所注册的HandlerMapping和HandlerAdapter我们都找到了。
然后我们就可以体验下RequestMappingHandlerMapping.
开启了<mvc:annotation-driven/>
,同时注册了两个bean。有RequestMappingHandlerMapping和RequestMappingHandlerAdapter作为后盾支持,然后我们就可以在bean中使用@Controller和@RequestMapping两个标签了。只要类含有@Controller或者含有@RequestMapping,RequestMappingHandlerMapping都会将他们纳入自己的handler管辖范围。所以仅仅在方法中含有@RequestMapping注解是不被处理的,必须在类上加入@RequestMapping或者@Controller
RequestMappingHandlerMapping在初始化时是如何寻找它所管辖的bean。
RequestMappingHandlerMapping的父类AbstractHandlerMethodMapping因为实现了InitializingBean接口,在初始化时会调用afterPropertiesSet方法,这个方法里又调用initHandlerMethods,在该方法中,遍历所有的bean然后判断他们是不是含有@Controller或者@RequestMapping注解:
AbstractHandlerMethodMapping类
public void afterPropertiesSet() {
initHandlerMethods();
}
protected void initHandlerMethods() {
if (logger.isDebugEnabled()) {
logger.debug("Looking for request mappings in application context: " + getApplicationContext());
}
String[] beanNames = (this.detectHandlerMethodsInAncestorContexts ?
BeanFactoryUtils.beanNamesForTypeIncludingAncestors(getApplicationContext(), Object.class) :
getApplicationContext().getBeanNamesForType(Object.class));
for (String beanName : beanNames) {
if (!beanName.startsWith(SCOPED_TARGET_NAME_PREFIX)) {
Class<?> beanType = null;
try {
beanType = getApplicationContext().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);
}
}
if (beanType != null && isHandler(beanType)) {
detectHandlerMethods(beanName);
}
}
}
handlerMethodsInitialized(getHandlerMethods());
}
isHandler
如果handler含有了上述注解@Controller或者@RequestMapping的其中之一,就会进一步处理该handler的方法中
@Override
protected boolean isHandler(Class<?> beanType) {
return (AnnotatedElementUtils.hasAnnotation(beanType, Controller.class) ||
AnnotatedElementUtils.hasAnnotation(beanType, RequestMapping.class));
}
detectHandlerMethods方法
protected void detectHandlerMethods(final Object handler) {
Class<?> handlerType = (handler instanceof String ?
getApplicationContext().getType((String) handler) : handler.getClass());
final Class<?> userType = ClassUtils.getUserClass(handlerType);
//遍历这个handler类的所有方法
Map<Method, T> methods = MethodIntrospector.selectMethods(userType,
new MethodIntrospector.MetadataLookup<T>() {
@Override
public T inspect(Method method) {
try {
//找到RequestMapping得注解的方法构建一个RequestMappingInfo对象。
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);
}
//对handler的所有方法过滤完成之后,就要遍历这些方法,以一定的方式存储起来。
for (Map.Entry<Method, T> entry : methods.entrySet()) {
Method invocableMethod = AopUtils.selectInvocableMethod(entry.getKey(), userType);
T mapping = entry.getValue();
registerHandlerMethod(handler, invocableMethod, mapping);
}
}
@Override
protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {
RequestMappingInfo info = createRequestMappingInfo(method);
if (info != null) {
RequestMappingInfo typeInfo = createRequestMappingInfo(handlerType);
if (typeInfo != null) {
info = typeInfo.combine(info);
}
}
return info;
}
找到RequestMapping得注解的方法构建一个RequestMappingInfo对象。
private RequestMappingInfo createRequestMappingInfo(AnnotatedElement element) {
RequestMapping requestMapping = AnnotatedElementUtils.findMergedAnnotation(element, RequestMapping.class);
RequestCondition<?> condition = (element instanceof Class<?> ?
getCustomTypeCondition((Class<?>) element) : getCustomMethodCondition((Method) element));
return (requestMapping != null ? createRequestMappingInfo(requestMapping, condition) : null);
}
构建一个RequestMappingInfo对象
protected RequestMappingInfo createRequestMappingInfo(
RequestMapping requestMapping, RequestCondition<?> customCondition) {
return RequestMappingInfo
.paths(resolveEmbeddedValuesInPatterns(requestMapping.path()))
.methods(requestMapping.method())
.params(requestMapping.params())
.headers(requestMapping.headers())
.consumes(requestMapping.consumes())
.produces(requestMapping.produces())
.mappingName(requestMapping.name())
.customCondition(customCondition)
.options(this.config)
.build();
}
mappingRegistry存储mapping, handler, method
protected void registerHandlerMethod(Object handler, Method method, T mapping) {
this.mappingRegistry.register(mapping, handler, method);
}
public void register(T mapping, Object handler, Method method) {
this.readWriteLock.writeLock().lock();
try {
//
HandlerMethod handlerMethod = createHandlerMethod(handler, method);
assertUniqueMethodMapping(handlerMethod, mapping);
if (logger.isInfoEnabled()) {
logger.info("Mapped \"" + mapping + "\" onto " + handlerMethod);
}
this.mappingLookup.put(mapping, handlerMethod);
List<String> directUrls = getDirectUrls(mapping);
for (String url : directUrls) {
this.urlLookup.add(url, mapping);
}
String name = null;
if (getNamingStrategy() != null) {
name = getNamingStrategy().getName(handlerMethod, mapping);
addMappingName(name, handlerMethod);
}
CorsConfiguration corsConfig = initCorsConfiguration(handler, method, mapping);
if (corsConfig != null) {
this.corsLookup.put(handlerMethod, corsConfig);
}
这里的this.registry就包含了所有管辖的bean,key为RequestMappingInfo对象,value为handler和它中含有@RequestMapping注释的方法method构建的HandlerMethod。
this.registry.put(mapping, new MappingRegistration<>(mapping, handlerMethod, directUrls, name));
}
finally {
this.readWriteLock.writeLock().unlock();
}
}
至此,RequestMappingHandlerMapping的初始化注册工作就完成了.
这里的registry将会等待http的请求来匹配