/**
* AbstractHandlerMethodAdapter类的子类，支持@RequestMapping注解
* 若要自定义参数和返回值类型的支持可以通过setCustomArgumentResolvers和setCustomReturnValueHandlers两个方法
*或者，要重新配置所有参数和返回值类型，
*使用setArgumentResolvers和setReturnValueHandlers方法。
*/
public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
implements BeanFactoryAware, InitializingBean {
}在spring-boot框架启动的过程中，这个类是肯定会执行到的，次序位于设置supportMediaType和convertors之后。
这个类是@RequestMapping注解的处理器适配器类，有个疑问，这个类为什么是@RequestMapping注解的处理器类，是在哪里配置的，注释里虽然这么说了，是怎么配置上的呢？
再看里面的方法以及成员变量
/**
* MethodFilter that matches {@link InitBinder @InitBinder} methods.
*/
public static final MethodFilter INIT_BINDER_METHODS = method ->
AnnotatedElementUtils.hasAnnotation(method, InitBinder.class);
/**
* MethodFilter that matches {@link ModelAttribute @ModelAttribute} methods.
*/
public static final MethodFilter MODEL_ATTRIBUTE_METHODS = method ->
(!AnnotatedElementUtils.hasAnnotation(method, RequestMapping.class) &&
AnnotatedElementUtils.hasAnnotation(method, ModelAttribute.class));
@Nullable
private List<HandlerMethodArgumentResolver> customArgumentResolvers;
// 用于给处理器方法和注释了@ModelAttribute的方法设置参数
@Nullable
private HandlerMethodArgumentResolverComposite argumentResolvers;
// 用于给注释了@initBinder的方法设置参数
@Nullable
private HandlerMethodArgumentResolverComposite initBinderArgumentResolvers;
@Nullable
private List<HandlerMethodReturnValueHandler> customReturnValueHandlers;
// 用于将处理器的返回值处理成ModelAndView的类型
@Nullable
private HandlerMethodReturnValueHandlerComposite returnValueHandlers;
@Nullable
private List<ModelAndViewResolver> modelAndViewResolvers;
private ContentNegotiationManager contentNegotiationManager = new ContentNegotiationManager();
private List<HttpMessageConverter<?>> messageConverters;
// 用于保存实现了ResponseBodyAdvice接口，可以修改返回的ResponseBody的类
private final List<Object> requestResponseBodyAdvice = new ArrayList<>();
@Nullable
private WebBindingInitializer webBindingInitializer;
private AsyncTaskExecutor taskExecutor = new SimpleAsyncTaskExecutor("MvcAsync");
@Nullable
private Long asyncRequestTimeout;
private CallableProcessingInterceptor[] callableInterceptors = new CallableProcessingInterceptor[0];
private DeferredResultProcessingInterceptor[] deferredResultInterceptors = new DeferredResultProcessingInterceptor[0];
private ReactiveAdapterRegistry reactiveAdapterRegistry = ReactiveAdapterRegistry.getSharedInstance();
private boolean ignoreDefaultModelOnRedirect = false;
private int cacheSecondsForSessionAttributeHandlers = 0;
/**
* 是否对相同 Session 加锁
*/
private boolean synchronizeOnSession = false;
private SessionAttributeStore sessionAttributeStore = new DefaultSessionAttributeStore();
private ParameterNameDiscoverer parameterNameDiscoverer = new DefaultParameterNameDiscoverer();
@Nullable
private ConfigurableBeanFactory beanFactory;
// ========== 缓存 ==========
private final Map<Class<?>, SessionAttributesHandler> sessionAttributesHandlerCache = new ConcurrentHashMap<>(64);
private final Map<Class<?>, Set<Method>> initBinderCache = new ConcurrentHashMap<>(64);
// 用于缓存@controllerAdvice注释的类里面注释了@InitBinder的方法
private final Map<ControllerAdviceBean, Set<Method>> initBinderAdviceCache = new LinkedHashMap<>();
private final Map<Class<?>, Set<Method>> modelAttributeCache = new ConcurrentHashMap<>(64);
// 用于缓存@ControllerADvice注释的类里注释了@ModelAttribute的方法
private final Map<ControllerAdviceBean, Set<Method>> modelAttributeAdviceCache = new LinkedHashMap<>();
public RequestMappingHandlerAdapter() {
// 初始化 messageConverters
this.messageConverters = new ArrayList<>(4);
this.messageConverters.add(new ByteArrayHttpMessageConverter());
this.messageConverters.add(new StringHttpMessageConverter());
try {
this.messageConverters.add(new SourceHttpMessageConverter<>());
}
catch (Error err) {
// Ignore when no TransformerFactory implementation is available
}
this.messageConverters.add(new AllEncompassingFormHttpMessageConverter());
}
/**
* Provide resolvers for custom argument types. Custom resolvers are ordered
* after built-in ones. To override the built-in support for argument
* resolution use {@link #setArgumentResolvers} instead.
*/
public void setCustomArgumentResolvers(@Nullable List<HandlerMethodArgumentResolver> argumentResolvers) {
this.customArgumentResolvers = argumentResolvers;
}
/**
* Return the custom argument resolvers, or {@code null}.
*/
@Nullable
public List<HandlerMethodArgumentResolver> getCustomArgumentResolvers() {
return this.customArgumentResolvers;
}
/**
* Configure the complete list of supported argument types thus overriding
* the resolvers that would otherwise be configured by default.
*/
public void setArgumentResolvers(@Nullable List<HandlerMethodArgumentResolver> argumentResolvers) {
if (argumentResolvers == null) {
this.argumentResolvers = null;
}
else {
this.argumentResolvers = new HandlerMethodArgumentResolverComposite();
this.argumentResolvers.addResolvers(argumentResolvers);
}
}
/**
* Return the configured argument resolvers, or possibly {@code null} if
* not initialized yet via {@link #afterPropertiesSet()}.
*/
@Nullable
public List<HandlerMethodArgumentResolver> getArgumentResolvers() {
return (this.argumentResolvers != null ? this.argumentResolvers.getResolvers() : null);
}
/**
* Configure the supported argument types in {@code @InitBinder} methods.
*/
public void setInitBinderArgumentResolvers(@Nullable List<HandlerMethodArgumentResolver> argumentResolvers) {
if (argumentResolvers == null) {
this.initBinderArgumentResolvers = null;
}
else {
this.initBinderArgumentResolvers = new HandlerMethodArgumentResolverComposite();
this.initBinderArgumentResolvers.addResolvers(argumentResolvers);
}
}
/**
* Return the argument resolvers for {@code @InitBinder} methods, or possibly
* {@code null} if not initialized yet via {@link #afterPropertiesSet()}.
*/
@Nullable
public List<HandlerMethodArgumentResolver> getInitBinderArgumentResolvers() {
return (this.initBinderArgumentResolvers != null ? this.initBinderArgumentResolvers.getResolvers() : null);
}
/**
* Provide handlers for custom return value types. Custom handlers are
* ordered after built-in ones. To override the built-in support for
* return value handling use {@link #setReturnValueHandlers}.
*/
public void setCustomReturnValueHandlers(@Nullable List<HandlerMethodReturnValueHandler> returnValueHandlers) {
this.customReturnValueHandlers = returnValueHandlers;
}
/**
* Return the custom return value handlers, or {@code null}.
*/
@Nullable
public List<HandlerMethodReturnValueHandler> getCustomReturnValueHandlers() {
return this.customReturnValueHandlers;
}
/**
* Configure the complete list of supported return value types thus
* overriding handlers that would otherwise be configured by default.
*/
public void setReturnValueHandlers(@Nullable List<HandlerMethodReturnValueHandler> returnValueHandlers) {
if (returnValueHandlers == null) {
this.returnValueHandlers = null;
}
else {
this.returnValueHandlers = new HandlerMethodReturnValueHandlerComposite();
this.returnValueHandlers.addHandlers(returnValueHandlers);
}
}
/**
* Return the configured handlers, or possibly {@code null} if not
* initialized yet via {@link #afterPropertiesSet()}.
*/
@Nullable
public List<HandlerMethodReturnValueHandler> getReturnValueHandlers() {
return (this.returnValueHandlers != null ? this.returnValueHandlers.getHandlers() : null);
}
/**
* Provide custom {@link ModelAndViewResolver ModelAndViewResolvers}.
* <p><strong>Note:</strong> This method is available for backwards
* compatibility only. However, it is recommended to re-write a
* {@code ModelAndViewResolver} as {@link HandlerMethodReturnValueHandler}.
* An adapter between the two interfaces is not possible since the
* {@link HandlerMethodReturnValueHandler#supportsReturnType} method
* cannot be implemented. Hence {@code ModelAndViewResolver}s are limited
* to always being invoked at the end after all other return value
* handlers have been given a chance.
* <p>A {@code HandlerMethodReturnValueHandler} provides better access to
* the return type and controller method information and can be ordered
* freely relative to other return value handlers.
*/
public void setModelAndViewResolvers(@Nullable List<ModelAndViewResolver> modelAndViewResolvers) {
this.modelAndViewResolvers = modelAndViewResolvers;
}
/**
* Return the configured {@link ModelAndViewResolver ModelAndViewResolvers}, or {@code null}.
*/
@Nullable
public List<ModelAndViewResolver> getModelAndViewResolvers() {
return this.modelAndViewResolvers;
}
/**
* Set the {@link ContentNegotiationManager} to use to determine requested media types.
* If not set, the default constructor is used.
*/
public void setContentNegotiationManager(ContentNegotiationManager contentNegotiationManager) {
this.contentNegotiationManager = contentNegotiationManager;
}
/**
* Provide the converters to use in argument resolvers and return value
* handlers that support reading and/or writing to the body of the
* request and response.
*/
public void setMessageConverters(List<HttpMessageConverter<?>> messageConverters) {
this.messageConverters = messageConverters;
}
/**
* Return the configured message body converters.
*/
public List<HttpMessageConverter<?>> getMessageConverters() {
return this.messageConverters;
}
/**
* Add one or more {@code RequestBodyAdvice} instances to intercept the
* request before it is read and converted for {@code @RequestBody} and
* {@code HttpEntity} method arguments.
*/
public void setRequestBodyAdvice(@Nullable List<RequestBodyAdvice> requestBodyAdvice) {
if (requestBodyAdvice != null) {
this.requestResponseBodyAdvice.addAll(requestBodyAdvice);
}
}
/**
* Add one or more {@code ResponseBodyAdvice} instances to intercept the
* response before {@code @ResponseBody} or {@code ResponseEntity} return
* values are written to the response body.
*/
public void setResponseBodyAdvice(@Nullable List<ResponseBodyAdvice<?>> responseBodyAdvice) {
if (responseBodyAdvice != null) {
this.requestResponseBodyAdvice.addAll(responseBodyAdvice);
}
}
/**
* Provide a WebBindingInitializer with "global" initialization to apply
* to every DataBinder instance.
*/
public void setWebBindingInitializer(@Nullable WebBindingInitializer webBindingInitializer) {
this.webBindingInitializer = webBindingInitializer;
}
/**
* Return the configured WebBindingInitializer, or {@code null} if none.
*/
@Nullable
public WebBindingInitializer getWebBindingInitializer() {
return this.webBindingInitializer;
}
/**
* Set the default {@link AsyncTaskExecutor} to use when a controller method
* return a {@link Callable}. Controller methods can override this default on
* a per-request basis by returning an {@link WebAsyncTask}.
* <p>By default a {@link SimpleAsyncTaskExecutor} instance is used.
* It's recommended to change that default in production as the simple executor
* does not re-use threads.
*/
public void setTaskExecutor(AsyncTaskExecutor taskExecutor) {
this.taskExecutor = taskExecutor;
}
/**
* Specify the amount of time, in milliseconds, before concurrent handling
* should time out. In Servlet 3, the timeout begins after the main request
* processing thread has exited and ends when the request is dispatched again
* for further processing of the concurrently produced result.
* <p>If this value is not set, the default timeout of the underlying
* implementation is used.
* @param timeout the timeout value in milliseconds
*/
public void setAsyncRequestTimeout(long timeout) {
this.asyncRequestTimeout = timeout;
}
/**
* Configure {@code CallableProcessingInterceptor}'s to register on async requests.
* @param interceptors the interceptors to register
*/
public void setCallableInterceptors(List<CallableProcessingInterceptor> interceptors) {
this.callableInterceptors = interceptors.toArray(new CallableProcessingInterceptor[0]);
}
/**
* Configure {@code DeferredResultProcessingInterceptor}'s to register on async requests.
* @param interceptors the interceptors to register
*/
public void setDeferredResultInterceptors(List<DeferredResultProcessingInterceptor> interceptors) {
this.deferredResultInterceptors = interceptors.toArray(new DeferredResultProcessingInterceptor[0]);
}
/**
* Configure the registry for reactive library types to be supported as
* return values from controller methods.
* @since 5.0.5
*/
public void setReactiveAdapterRegistry(ReactiveAdapterRegistry reactiveAdapterRegistry) {
this.reactiveAdapterRegistry = reactiveAdapterRegistry;
}
/**
* Return the configured reactive type registry of adapters.
* @since 5.0
*/
public ReactiveAdapterRegistry getReactiveAdapterRegistry() {
return this.reactiveAdapterRegistry;
}
/**
* By default the content of the "default" model is used both during
* rendering and redirect scenarios. Alternatively a controller method
* can declare a {@link RedirectAttributes} argument and use it to provide
* attributes for a redirect.
* <p>Setting this flag to {@code true} guarantees the "default" model is
* never used in a redirect scenario even if a RedirectAttributes argument
* is not declared. Setting it to {@code false} means the "default" model
* may be used in a redirect if the controller method doesn't declare a
* RedirectAttributes argument.
* <p>The default setting is {@code false} but new applications should
* consider setting it to {@code true}.
* @see RedirectAttributes
*/
public void setIgnoreDefaultModelOnRedirect(boolean ignoreDefaultModelOnRedirect) {
this.ignoreDefaultModelOnRedirect = ignoreDefaultModelOnRedirect;
}
/**
* Specify the strategy to store session attributes with. The default is
* {@link org.springframework.web.bind.support.DefaultSessionAttributeStore},
* storing session attributes in the HttpSession with the same attribute
* name as in the model.
*/
public void setSessionAttributeStore(SessionAttributeStore sessionAttributeStore) {
this.sessionAttributeStore = sessionAttributeStore;
}
/**
* Cache content produced by {@code @SessionAttributes} annotated handlers
* for the given number of seconds.
* <p>Possible values are:
* <ul>
* <li>-1: no generation of cache-related headers</li>
* <li>0 (default value): "Cache-Control: no-store" will prevent caching</li>
* <li>1 or higher: "Cache-Control: max-age=seconds" will ask to cache content;
* not advised when dealing with session attributes</li>
* </ul>
* <p>In contrast to the "cacheSeconds" property which will apply to all general
* handlers (but not to {@code @SessionAttributes} annotated handlers),
* this setting will apply to {@code @SessionAttributes} handlers only.
* @see #setCacheSeconds
* @see org.springframework.web.bind.annotation.SessionAttributes
*/
public void setCacheSecondsForSessionAttributeHandlers(int cacheSecondsForSessionAttributeHandlers) {
this.cacheSecondsForSessionAttributeHandlers = cacheSecondsForSessionAttributeHandlers;
}
/**
* Set if controller execution should be synchronized on the session,
* to serialize parallel invocations from the same client.
* <p>More specifically, the execution of the {@code handleRequestInternal}
* method will get synchronized if this flag is "true". The best available
* session mutex will be used for the synchronization; ideally, this will
* be a mutex exposed by HttpSessionMutexListener.
* <p>The session mutex is guaranteed to be the same object during
* the entire lifetime of the session, available under the key defined
* by the {@code SESSION_MUTEX_ATTRIBUTE} constant. It serves as a
* safe reference to synchronize on for locking on the current session.
* <p>In many cases, the HttpSession reference itself is a safe mutex
* as well, since it will always be the same object reference for the
* same active logical session. However, this is not guaranteed across
* different servlet containers; the only 100% safe way is a session mutex.
* @see org.springframework.web.util.HttpSessionMutexListener
* @see org.springframework.web.util.WebUtils#getSessionMutex(javax.servlet.http.HttpSession)
*/
public void setSynchronizeOnSession(boolean synchronizeOnSession) {
this.synchronizeOnSession = synchronizeOnSession;
}
/**
* Set the ParameterNameDiscoverer to use for resolving method parameter names if needed
* (e.g. for default attribute names).
* <p>Default is a {@link org.springframework.core.DefaultParameterNameDiscoverer}.
*/
public void setParameterNameDiscoverer(ParameterNameDiscoverer parameterNameDiscoverer) {
this.parameterNameDiscoverer = parameterNameDiscoverer;
}
/**
* A {@link ConfigurableBeanFactory} is expected for resolving expressions
* in method argument default values.
*/
@Override
public void setBeanFactory(BeanFactory beanFactory) {
if (beanFactory instanceof ConfigurableBeanFactory) {
this.beanFactory = (ConfigurableBeanFactory) beanFactory;
}
}
/**
* Return the owning factory of this bean instance, or {@code null} if none.
*/
@Nullable
protected ConfigurableBeanFactory getBeanFactory() {
return this.beanFactory;
}
@Override
public void afterPropertiesSet() {
// Do this first, it may add ResponseBody advice beans
// 初始化注释了@ControllerAdvice的类的相关属性
initControllerAdviceCache();
// 初始化 argumentResolvers 属性
if (this.argumentResolvers == null) {
List<HandlerMethodArgumentResolver> resolvers = getDefaultArgumentResolvers();
this.argumentResolvers = new HandlerMethodArgumentResolverComposite().addResolvers(resolvers);
}
// 初始化 initBinderArgumentResolvers 属性
if (this.initBinderArgumentResolvers == null) {
List<HandlerMethodArgumentResolver> resolvers = getDefaultInitBinderArgumentResolvers();
this.initBinderArgumentResolvers = new HandlerMethodArgumentResolverComposite().addResolvers(resolvers);
}
// 初始化 returnValueHandlers 属性
if (this.returnValueHandlers == null) {
List<HandlerMethodReturnValueHandler> handlers = getDefaultReturnValueHandlers();
this.returnValueHandlers = new HandlerMethodReturnValueHandlerComposite().addHandlers(handlers);
}
}
private void initControllerAdviceCache() {
// 判断当前应用程序上下文是否为空，如果为空，直接返回
if (getApplicationContext() == null) {
return;
}
// 扫描@ControllerAdvice注解的Bean，生成对应的ControllerAdviceBean对象，并将进行排序
List<ControllerAdviceBean> adviceBeans = ControllerAdviceBean.findAnnotatedBeans(getApplicationContext());
List<Object> requestResponseBodyAdviceBeans = new ArrayList<>();
// 遍历ControllerAdviceBean数组
for (ControllerAdviceBean adviceBean : adviceBeans) {
Class<?> beanType = adviceBean.getBeanType();
if (beanType == null) {
throw new IllegalStateException("Unresolvable type for ControllerAdviceBean: " + adviceBean);
}
// 扫描有`@ModelAttribute`，无`@RequestMapping`注解的方法，添加到`modelAttributeAdviceCache`属性中
// 该类方法用于在执行方法前修改 Model 对象
Set<Method> attrMethods = MethodIntrospector.selectMethods(beanType, MODEL_ATTRIBUTE_METHODS);
if (!attrMethods.isEmpty()) {
this.modelAttributeAdviceCache.put(adviceBean, attrMethods);
}
// 扫描有`@InitBinder`注解的方法，添加到`initBinderAdviceCache`属性中
// 该类方法用于在执行方法前初始化数据绑定器
Set<Method> binderMethods = MethodIntrospector.selectMethods(beanType, INIT_BINDER_METHODS);
if (!binderMethods.isEmpty()) {
this.initBinderAdviceCache.put(adviceBean, binderMethods);
}
// 如果是RequestBodyAdvice或ResponseBodyAdvice的子类，添加到requestResponseBodyAdviceBeans中
if (RequestBodyAdvice.class.isAssignableFrom(beanType) || ResponseBodyAdvice.class.isAssignableFrom(beanType)) {
requestResponseBodyAdviceBeans.add(adviceBean);
}
}
// 将requestResponseBodyAdviceBeans添加到this.requestResponseBodyAdvice属性中
if (!requestResponseBodyAdviceBeans.isEmpty()) {
this.requestResponseBodyAdvice.addAll(0, requestResponseBodyAdviceBeans);
}
// 打印日志
if (logger.isDebugEnabled()) {
int modelSize = this.modelAttributeAdviceCache.size();
int binderSize = this.initBinderAdviceCache.size();
int reqCount = getBodyAdviceCount(RequestBodyAdvice.class);
int resCount = getBodyAdviceCount(ResponseBodyAdvice.class);
if (modelSize == 0 && binderSize == 0 && reqCount == 0 && resCount == 0) {
logger.debug("ControllerAdvice beans: none");
}
else {
logger.debug("ControllerAdvice beans: " + modelSize + " @ModelAttribute, " + binderSize +
" @InitBinder, " + reqCount + " RequestBodyAdvice, " + resCount + " ResponseBodyAdvice");
}
}
}
// Count all advice, including explicit registrations..
private int getBodyAdviceCount(Class<?> adviceType) {
List<Object> advice = this.requestResponseBodyAdvice;
return RequestBodyAdvice.class.isAssignableFrom(adviceType) ?
RequestResponseBodyAdviceChain.getAdviceByType(advice, RequestBodyAdvice.class).size() :
RequestResponseBodyAdviceChain.getAdviceByType(advice, ResponseBodyAdvice.class).size();
}
/**
* Return the list of argument resolvers to use including built-in resolvers
* and custom resolvers provided via {@link #setCustomArgumentResolvers}.
*/
private List<HandlerMethodArgumentResolver> getDefaultArgumentResolvers() {
List<HandlerMethodArgumentResolver> resolvers = new ArrayList<>(30);
// Annotation-based argument resolution
// 添加按注解解析参数的解析器
resolvers.add(new RequestParamMethodArgumentResolver(getBeanFactory(), false));
resolvers.add(new RequestParamMapMethodArgumentResolver());
resolvers.add(new PathVariableMethodArgumentResolver());
resolvers.add(new PathVariableMapMethodArgumentResolver());
resolvers.add(new MatrixVariableMethodArgumentResolver());
resolvers.add(new MatrixVariableMapMethodArgumentResolver());
resolvers.add(new ServletModelAttributeMethodProcessor(false));
resolvers.add(new RequestResponseBodyMethodProcessor(getMessageConverters(), this.requestResponseBodyAdvice));
resolvers.add(new RequestPartMethodArgumentResolver(getMessageConverters(), this.requestResponseBodyAdvice));
resolvers.add(new RequestHeaderMethodArgumentResolver(getBeanFactory()));
resolvers.add(new RequestHeaderMapMethodArgumentResolver());
resolvers.add(new ServletCookieValueMethodArgumentResolver(getBeanFactory()));
resolvers.add(new ExpressionValueMethodArgumentResolver(getBeanFactory()));
resolvers.add(new SessionAttributeMethodArgumentResolver());
resolvers.add(new RequestAttributeMethodArgumentResolver());
// Type-based argument resolution
// 添加按类型解析参数的解析器
resolvers.add(new ServletRequestMethodArgumentResolver());
resolvers.add(new ServletResponseMethodArgumentResolver());
resolvers.add(new HttpEntityMethodProcessor(getMessageConverters(), this.requestResponseBodyAdvice));
resolvers.add(new RedirectAttributesMethodArgumentResolver());
resolvers.add(new ModelMethodProcessor());
resolvers.add(new MapMethodProcessor());
resolvers.add(new ErrorsMethodArgumentResolver());
resolvers.add(new SessionStatusMethodArgumentResolver());
resolvers.add(new UriComponentsBuilderMethodArgumentResolver());
// Custom arguments
// 添加自定义参数解析器，主要用于解析自定义类型
if (getCustomArgumentResolvers() != null) {
resolvers.addAll(getCustomArgumentResolvers());
}
// Catch-all
// 最后两个解析器可以解析所有类型的参数
resolvers.add(new RequestParamMethodArgumentResolver(getBeanFactory(), true));
resolvers.add(new ServletModelAttributeMethodProcessor(true));
return resolvers;
}
/**
* Return the list of argument resolvers to use for {@code @InitBinder}
* methods including built-in and custom resolvers.
*/
private List<HandlerMethodArgumentResolver> getDefaultInitBinderArgumentResolvers() {
List<HandlerMethodArgumentResolver> resolvers = new ArrayList<>(20);
// Annotation-based argument resolution
resolvers.add(new RequestParamMethodArgumentResolver(getBeanFactory(), false));
resolvers.add(new RequestParamMapMethodArgumentResolver());
resolvers.add(new PathVariableMethodArgumentResolver());
resolvers.add(new PathVariableMapMethodArgumentResolver());
resolvers.add(new MatrixVariableMethodArgumentResolver());
resolvers.add(new MatrixVariableMapMethodArgumentResolver());
resolvers.add(new ExpressionValueMethodArgumentResolver(getBeanFactory()));
resolvers.add(new SessionAttributeMethodArgumentResolver());
resolvers.add(new RequestAttributeMethodArgumentResolver());
// Type-based argument resolution
resolvers.add(new ServletRequestMethodArgumentResolver());
resolvers.add(new ServletResponseMethodArgumentResolver());
// Custom arguments
if (getCustomArgumentResolvers() != null) {
resolvers.addAll(getCustomArgumentResolvers());
}
// Catch-all
resolvers.add(new RequestParamMethodArgumentResolver(getBeanFactory(), true));
return resolvers;
}
/**
* Return the list of return value handlers to use including built-in and
* custom handlers provided via {@link #setReturnValueHandlers}.
*/
private List<HandlerMethodReturnValueHandler> getDefaultReturnValueHandlers() {
List<HandlerMethodReturnValueHandler> handlers = new ArrayList<>(20);
// Single-purpose return value types
handlers.add(new ModelAndViewMethodReturnValueHandler());
handlers.add(new ModelMethodProcessor());
handlers.add(new ViewMethodReturnValueHandler());
handlers.add(new ResponseBodyEmitterReturnValueHandler(getMessageConverters(),
this.reactiveAdapterRegistry, this.taskExecutor, this.contentNegotiationManager));
handlers.add(new StreamingResponseBodyReturnValueHandler());
handlers.add(new HttpEntityMethodProcessor(getMessageConverters(),
this.contentNegotiationManager, this.requestResponseBodyAdvice));
handlers.add(new HttpHeadersReturnValueHandler());
handlers.add(new CallableMethodReturnValueHandler());
handlers.add(new DeferredResultMethodReturnValueHandler());
handlers.add(new AsyncTaskMethodReturnValueHandler(this.beanFactory));
// Annotation-based return value types
handlers.add(new ModelAttributeMethodProcessor(false));
handlers.add(new RequestResponseBodyMethodProcessor(getMessageConverters(),
this.contentNegotiationManager, this.requestResponseBodyAdvice));
// Multi-purpose return value types
handlers.add(new ViewNameMethodReturnValueHandler());
handlers.add(new MapMethodProcessor());
// Custom return value types
if (getCustomReturnValueHandlers() != null) {
handlers.addAll(getCustomReturnValueHandlers());
}
// Catch-all
if (!CollectionUtils.isEmpty(getModelAndViewResolvers())) {
handlers.add(new ModelAndViewResolverMethodReturnValueHandler(getModelAndViewResolvers()));
}
else {
handlers.add(new ModelAttributeMethodProcessor(true));
}
return handlers;
}
/**
* Always return {@code true} since any method argument and return value
* type will be processed in some way. A method argument not recognized
* by any HandlerMethodArgumentResolver is interpreted as a request parameter
* if it is a simple type, or as a model attribute otherwise. A return value
* not recognized by any HandlerMethodReturnValueHandler will be interpreted
* as a model attribute.
*/
@Override
protected boolean supportsInternal(HandlerMethod handlerMethod) {
return true;
}
@Override
protected ModelAndView handleInternal(HttpServletRequest request,
HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
ModelAndView mav;
// 校验请求（HttpMethod 和 Session 的校验）
checkRequest(request);
// Execute invokeHandlerMethod in synchronized block if required.
// 如果synchronizeOnSession为true，则对session进行同步，否则不同步
if (this.synchronizeOnSession) {
// 同步相同 Session 的逻辑，默认情况false
HttpSession session = request.getSession(false);
if (session != null) {
// 获取Session的锁对象
Object mutex = WebUtils.getSessionMutex(session);
synchronized (mutex) {
mav = invokeHandlerMethod(request, response, handlerMethod);
}
}
else {
// No HttpSession available -> no mutex necessary
mav = invokeHandlerMethod(request, response, handlerMethod);
}
}
else {
// No synchronization on session demanded at all...
mav = invokeHandlerMethod(request, response, handlerMethod);
}
// 响应不包含'Cache-Control'头
if (!response.containsHeader(HEADER_CACHE_CONTROL)) {
if (getSessionAttributesHandler(handlerMethod).hasSessionAttributes()) {
applyCacheSeconds(response, this.cacheSecondsForSessionAttributeHandlers);
}
else {
prepareResponse(response);
}
}
return mav;
}
/**
* This implementation always returns -1. An {@code @RequestMapping} method can
* calculate the lastModified value, call {@link WebRequest#checkNotModified(long)},
* and return {@code null} if the result of that call is {@code true}.
*/
@Override
protected long getLastModifiedInternal(HttpServletRequest request, HandlerMethod handlerMethod) {
return -1;
}
/**
* Return the {@link SessionAttributesHandler} instance for the given handler type
* (never {@code null}).
*/
private SessionAttributesHandler getSessionAttributesHandler(HandlerMethod handlerMethod) {
return this.sessionAttributesHandlerCache.computeIfAbsent(
handlerMethod.getBeanType(),
type -> new SessionAttributesHandler(type, this.sessionAttributeStore));
}
/**
* Invoke the {@link RequestMapping} handler method preparing a {@link ModelAndView}
* if view resolution is required.
* @since 4.2
* @see #createInvocableHandlerMethod(HandlerMethod)
*/
@Nullable
protected ModelAndView invokeHandlerMethod(HttpServletRequest request,
HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
// 使用request和response创建ServletWebRequest对象
ServletWebRequest webRequest = new ServletWebRequest(request, response);
try {
// 创建WebDataBinderFactory对象，此对象用来创建WebDataBinder对象，进行参数绑定，
// 实现参数跟String之间的类型转换，ArgumentResolver在进行参数解析的过程中会用到WebDataBinder
WebDataBinderFactory binderFactory = getDataBinderFactory(handlerMethod);
// 创建ModelFactory对象，此对象主要用来处理model，主要是两个功能，1是在处理器具体处理之前对model进行初始化，2是在处理完请求后对model参数进行更新
ModelFactory modelFactory = getModelFactory(handlerMethod, binderFactory);
// 创建ServletInvocableHandlerMethod对象，并设置其相关属性，实际的请求处理就是通过此对象来完成的,参数绑定、处理请求以及返回值处理都在里边完成
ServletInvocableHandlerMethod invocableMethod = createInvocableHandlerMethod(handlerMethod);
// 设置参数处理器
if (this.argumentResolvers != null) {
invocableMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
}
// 设置返回值处理器
if (this.returnValueHandlers != null) {
invocableMethod.setHandlerMethodReturnValueHandlers(this.returnValueHandlers);
}
// 设置参数绑定工厂对象
invocableMethod.setDataBinderFactory(binderFactory);
// 设置参数名称发现器
invocableMethod.setParameterNameDiscoverer(this.parameterNameDiscoverer);
// 创建ModelAndViewContainer对象，用于保存model和View对象
ModelAndViewContainer mavContainer = new ModelAndViewContainer();
// 将flashmap中的数据设置到model中
mavContainer.addAllAttributes(RequestContextUtils.getInputFlashMap(request));
// 使用modelFactory将sessionAttributes和注释了@ModelAttribute的方法的参数设置到model中
modelFactory.initModel(webRequest, mavContainer, invocableMethod);
// 根据配置对ignoreDefaultModelOnRedirect进行设置
mavContainer.setIgnoreDefaultModelOnRedirect(this.ignoreDefaultModelOnRedirect);
// 创建AsyncWebRequest异步请求对象
AsyncWebRequest asyncWebRequest = WebAsyncUtils.createAsyncWebRequest(request, response);
asyncWebRequest.setTimeout(this.asyncRequestTimeout);
// 创建WebAsyncManager异步请求管理器对象
WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
asyncManager.setTaskExecutor(this.taskExecutor);
asyncManager.setAsyncWebRequest(asyncWebRequest);
asyncManager.registerCallableInterceptors(this.callableInterceptors);
asyncManager.registerDeferredResultInterceptors(this.deferredResultInterceptors);
if (asyncManager.hasConcurrentResult()) {
Object result = asyncManager.getConcurrentResult();
mavContainer = (ModelAndViewContainer) asyncManager.getConcurrentResultContext()[0];
asyncManager.clearConcurrentResult();
LogFormatUtils.traceDebug(logger, traceOn -> {
String formatted = LogFormatUtils.formatValue(result, !traceOn);
return "Resume with async result [" + formatted + "]";
});
invocableMethod = invocableMethod.wrapConcurrentResult(result);
}
// 执行调用
invocableMethod.invokeAndHandle(webRequest, mavContainer);
if (asyncManager.isConcurrentHandlingStarted()) {
return null;
}
// 处理完请求后的后置处理，此处一共做了三件事，
// 1、调用ModelFactory的updateModel方法更新model，包括设置SessionAttribute和给Model设置BinderResult
// 2、根据mavContainer创建了ModelAndView
// 3、如果mavContainer里的model是RedirectAttributes类型，则将其设置到FlashMap
return getModelAndView(mavContainer, modelFactory, webRequest);
}
finally {
// 标记请求完成
webRequest.requestCompleted();
}
}
/**
* Create a {@link ServletInvocableHandlerMethod} from the given {@link HandlerMethod} definition.
* @param handlerMethod the {@link HandlerMethod} definition
* @return the corresponding {@link ServletInvocableHandlerMethod} (or custom subclass thereof)
* @since 4.2
*/
protected ServletInvocableHandlerMethod createInvocableHandlerMethod(HandlerMethod handlerMethod) {
return new ServletInvocableHandlerMethod(handlerMethod);
}
private ModelFactory getModelFactory(HandlerMethod handlerMethod, WebDataBinderFactory binderFactory) {
// 获取sessionAttributesHandler
SessionAttributesHandler sessionAttrHandler = getSessionAttributesHandler(handlerMethod);
// 获取处理器类的类型
Class<?> handlerType = handlerMethod.getBeanType();
// 获取处理器类中注释了@modelAttribute而且没有注释@RequestMapping的类型，第一个获取后添加到缓存，以后直接从缓存中获取
Set<Method> methods = this.modelAttributeCache.get(handlerType);
if (methods == null) {
methods = MethodIntrospector.selectMethods(handlerType, MODEL_ATTRIBUTE_METHODS);
this.modelAttributeCache.put(handlerType, methods);
}
// 注释了@ModelAttribute的方法
List<InvocableHandlerMethod> attrMethods = new ArrayList<>();
// Global methods first
// 先添加全局的@ModelAttribute方法，后添加当前处理器定义的@ModelAttribute方法
this.modelAttributeAdviceCache.forEach((controllerAdviceBean, methodSet) -> {
if (controllerAdviceBean.isApplicableToBeanType(handlerType)) {
Object bean = controllerAdviceBean.resolveBean();
for (Method method : methodSet) {
attrMethods.add(createModelAttributeMethod(binderFactory, bean, method));
}
}
});
for (Method method : methods) {
Object bean = handlerMethod.getBean();
attrMethods.add(createModelAttributeMethod(binderFactory, bean, method));
}
// 新建ModelFactory对象，此处需要三个参数，第一个是注释了@ModelAttribute的方法，第二个是WebDataBinderFactory,第三个是SessionAttributeHandler
return new ModelFactory(attrMethods, binderFactory, sessionAttrHandler);
}
private InvocableHandlerMethod createModelAttributeMethod(WebDataBinderFactory factory, Object bean, Method method) {
InvocableHandlerMethod attrMethod = new InvocableHandlerMethod(bean, method);
if (this.argumentResolvers != null) {
attrMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
}
attrMethod.setParameterNameDiscoverer(this.parameterNameDiscoverer);
attrMethod.setDataBinderFactory(factory);
return attrMethod;
}
private WebDataBinderFactory getDataBinderFactory(HandlerMethod handlerMethod) throws Exception {
Class<?> handlerType = handlerMethod.getBeanType();
// 检查当前Handler中的initBinder方法是否已经存在于缓存中
Set<Method> methods = this.initBinderCache.get(handlerType);
// 如果没有则查找并设置到缓冲中
if (methods == null) {
methods = MethodIntrospector.selectMethods(handlerType, INIT_BINDER_METHODS);// 将当前Controller中所有被@InitBinder注解修饰的方法都获取到
this.initBinderCache.put(handlerType, methods);
}
// 定义保存InitBinder方法的临时变量
List<InvocableHandlerMethod> initBinderMethods = new ArrayList<>();
// Global methods first
// 将所有符合条件的全局InitBinder方法添加到initBinderMethods
this.initBinderAdviceCache.forEach((controllerAdviceBean, methodSet) -> {
if (controllerAdviceBean.isApplicableToBeanType(handlerType)) {
Object bean = controllerAdviceBean.resolveBean();
for (Method method : methodSet) {
initBinderMethods.add(createInitBinderMethod(bean, method));
}
}
});
// 将当前handler中的initBinder方法添加到initBinderMethods
for (Method method : methods) {
// 创建当前方法对应的bean对象
Object bean = handlerMethod.getBean();
// 将method适配为可执行的invocableHandlerMethod
initBinderMethods.add(createInitBinderMethod(bean, method));
}
// 创建DataBinderFactory并返回
return createDataBinderFactory(initBinderMethods);
}
private InvocableHandlerMethod createInitBinderMethod(Object bean, Method method) {
InvocableHandlerMethod binderMethod = new InvocableHandlerMethod(bean, method);
if (this.initBinderArgumentResolvers != null) {
binderMethod.setHandlerMethodArgumentResolvers(this.initBinderArgumentResolvers);
}
binderMethod.setDataBinderFactory(new DefaultDataBinderFactory(this.webBindingInitializer));
binderMethod.setParameterNameDiscoverer(this.parameterNameDiscoverer);
return binderMethod;
}
/**
* Template method to create a new InitBinderDataBinderFactory instance.
* <p>The default implementation creates a ServletRequestDataBinderFactory.
* This can be overridden for custom ServletRequestDataBinder subclasses.
* @param binderMethods {@code @InitBinder} methods
* @return the InitBinderDataBinderFactory instance to use
* @throws Exception in case of invalid state or arguments
*/
protected InitBinderDataBinderFactory createDataBinderFactory(List<InvocableHandlerMethod> binderMethods)
throws Exception {
return new ServletRequestDataBinderFactory(binderMethods, getWebBindingInitializer());
}
@Nullable
private ModelAndView getModelAndView(ModelAndViewContainer mavContainer,
ModelFactory modelFactory, NativeWebRequest webRequest) throws Exception {
// 更新model(设置sessionAttributes和给model设置BindingResult)
modelFactory.updateModel(webRequest, mavContainer);
// 情况一，如果 mavContainer 已处理，则返回“空”的 ModelAndView 对象。
if (mavContainer.isRequestHandled()) {
return null;
}
// 情况二，如果mavContainer未处理，则基于`mavContainer`生成ModelAndView对象
ModelMap model = mavContainer.getModel();
// 创建 ModelAndView 对象，并设置相关属性
ModelAndView mav = new ModelAndView(mavContainer.getViewName(), model, mavContainer.getStatus());
// 如果mavContainer里的view不是引用，也就是不是string类型，则设置到mv中
if (!mavContainer.isViewReference()) {
mav.setView((View) mavContainer.getView());
}
if (model instanceof RedirectAttributes) {
Map<String, ?> flashAttributes = ((RedirectAttributes) model).getFlashAttributes();
HttpServletRequest request = webRequest.getNativeRequest(HttpServletRequest.class);
if (request != null) {
RequestContextUtils.getOutputFlashMap(request).putAll(flashAttributes);
}
}
return mav;
}