Springmvc整体工作流程
DispatcherServlet本质是HttpServlet，是Springmvc的http请求分发控制器，是Springmvc整体工作流程的核心。
DispatcherServlet类结构继承图
在../WEB-INF/web.xml中配置如下：
<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/classes/META-INF/spring/springmvc-servlet.xml</param-value>
</init-param>
<!-- <load-on-startup>1</load-on-startup> -->
</servlet>
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>
通过在web.xml中配置contextConfigLocation，指定了Springmvc的核心配置文件。
Springmvc整体工作流程示意图
Springmvc整体工作流程实现简图
初始化
Springmvc的初始化体现为DispatcherServlet的初始化：1）完成Springmvc容器XmlWebApplicationContext的创建、配置及refresh；2）完成其组件的初始化。
Springmvc核心配置文件springmvc-servlet.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
<!-- scan the package and the sub package -->
<context:component-scan base-package="com.bitvalue"/>
<!-- don't handle the static resource -->
<mvc:default-servlet-handler />
<!-- if you use annotation you must configure following setting -->
<mvc:annotation-driven />
<!-- configure the InternalResourceViewResolver -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"
id="internalResourceViewResolver">
<!-- 前缀 -->
<property name="prefix" value="/WEB-INF/pages/" />
<!-- 后缀 -->
<property name="suffix" value=".jsp" />
<property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
</bean>
<!-- 支持上传文件 -->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"/>
<!-- 拦截器 -->
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/test/**" />
<bean class="org.test.interceptor.TestInterceptor"/>
</mvc:interceptor>
</mvc:interceptors>
</beans>
XmlWebApplicationContext容器的创建、配置及refresh
组件初始化
相关源码
在“XmlWebApplicationContext容器的创建、配置及refresh”初始化阶段涉及Springmvc配置文件的解析及XmlWebApplicationContext容器中相关bean的实例化。
<mvc>标签元素解析
/** MvcNamespaceHandler.java */
public class MvcNamespaceHandler extends NamespaceHandlerSupport {
// <mvc>相应标签元素解析
public void init() {
// 注册<mvc:annotation-driven />解析的BeanDefinitionParser
registerBeanDefinitionParser("annotation-driven", new AnnotationDrivenBeanDefinitionParser());
// 注册<mvc:default-servlet-handler />解析的BeanDefinitionParser
registerBeanDefinitionParser("default-servlet-handler", new DefaultServletHandlerBeanDefinitionParser());
// 注册<mvc:interceptors />解析的BeanDefinitionParser
registerBeanDefinitionParser("interceptors", new InterceptorsBeanDefinitionParser());
// 注册<mvc:resources />解析的BeanDefinitionParser
registerBeanDefinitionParser("resources", new ResourcesBeanDefinitionParser());
// 注册<mvc:view-controller />解析的BeanDefinitionParser
registerBeanDefinitionParser("view-controller", new ViewControllerBeanDefinitionParser());
}
}
/** AnnotationDrivenBeanDefinitionParser.java */
public BeanDefinition parse(Element element, ParserContext parserContext) {
Object source = parserContext.extractSource(element);
CompositeComponentDefinition compDefinition = new CompositeComponentDefinition(element.getTagName(), source);
parserContext.pushContainingComponent(compDefinition);
RuntimeBeanReference contentNegotiationManager = getContentNegotiationManager(element, source, parserContext);
// RequestMappingHandlerMapping RootBeanDefinition
RootBeanDefinition handlerMappingDef = new RootBeanDefinition(RequestMappingHandlerMapping.class);
handlerMappingDef.setSource(source);
handlerMappingDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
handlerMappingDef.getPropertyValues().add("order", 0);
handlerMappingDef.getPropertyValues().add("contentNegotiationManager", contentNegotiationManager);
String methodMappingName = parserContext.getReaderContext().registerWithGeneratedName(handlerMappingDef);
if (element.hasAttribute("enableMatrixVariables")) {
Boolean enableMatrixVariables = Boolean.valueOf(element.getAttribute("enableMatrixVariables"));
handlerMappingDef.getPropertyValues().add("removeSemicolonContent", !enableMatrixVariables);
}
RuntimeBeanReference conversionService = getConversionService(element, source, parserContext);
RuntimeBeanReference validator = getValidator(element, source, parserContext);
RuntimeBeanReference messageCodesResolver = getMessageCodesResolver(element);
// ConfigurableWebBindingInitializer RootBeanDefinition
RootBeanDefinition bindingDef = new RootBeanDefinition(ConfigurableWebBindingInitializer.class);
bindingDef.setSource(source);
bindingDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
bindingDef.getPropertyValues().add("conversionService", conversionService);
bindingDef.getPropertyValues().add("validator", validator);
bindingDef.getPropertyValues().add("messageCodesResolver", messageCodesResolver);
ManagedList<?> messageConverters = getMessageConverters(element, source, parserContext);
ManagedList<?> argumentResolvers = getArgumentResolvers(element, parserContext);
ManagedList<?> returnValueHandlers = getReturnValueHandlers(element, parserContext);
String asyncTimeout = getAsyncTimeout(element);
RuntimeBeanReference asyncExecutor = getAsyncExecutor(element);
ManagedList<?> callableInterceptors = getCallableInterceptors(element, source, parserContext);
ManagedList<?> deferredResultInterceptors = getDeferredResultInterceptors(element, source, parserContext);
// RequestMappingHandlerAdapter RootBeanDefinition
RootBeanDefinition handlerAdapterDef = new RootBeanDefinition(RequestMappingHandlerAdapter.class);
handlerAdapterDef.setSource(source);
handlerAdapterDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
handlerAdapterDef.getPropertyValues().add("contentNegotiationManager", contentNegotiationManager);
handlerAdapterDef.getPropertyValues().add("webBindingInitializer", bindingDef);
handlerAdapterDef.getPropertyValues().add("messageConverters", messageConverters);
if (element.hasAttribute("ignoreDefaultModelOnRedirect")) {
Boolean ignoreDefaultModel = Boolean.valueOf(element.getAttribute("ignoreDefaultModelOnRedirect"));
handlerAdapterDef.getPropertyValues().add("ignoreDefaultModelOnRedirect", ignoreDefaultModel);
}
if (argumentResolvers != null) {
handlerAdapterDef.getPropertyValues().add("customArgumentResolvers", argumentResolvers);
}
if (returnValueHandlers != null) {
handlerAdapterDef.getPropertyValues().add("customReturnValueHandlers", returnValueHandlers);
}
if (asyncTimeout != null) {
handlerAdapterDef.getPropertyValues().add("asyncRequestTimeout", asyncTimeout);
}
if (asyncExecutor != null) {
handlerAdapterDef.getPropertyValues().add("taskExecutor", asyncExecutor);
}
handlerAdapterDef.getPropertyValues().add("callableInterceptors", callableInterceptors);
handlerAdapterDef.getPropertyValues().add("deferredResultInterceptors", deferredResultInterceptors);
String handlerAdapterName = parserContext.getReaderContext().registerWithGeneratedName(handlerAdapterDef);
// ConversionServiceExposingInterceptor RootBeanDefinition
RootBeanDefinition csInterceptorDef = new RootBeanDefinition(ConversionServiceExposingInterceptor.class);
csInterceptorDef.setSource(source);
csInterceptorDef.getConstructorArgumentValues().addIndexedArgumentValue(0, conversionService);
// MappedInterceptor RootBeanDefinition
RootBeanDefinition mappedCsInterceptorDef = new RootBeanDefinition(MappedInterceptor.class);
mappedCsInterceptorDef.setSource(source);
mappedCsInterceptorDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
mappedCsInterceptorDef.getConstructorArgumentValues().addIndexedArgumentValue(0, (Object) null);
mappedCsInterceptorDef.getConstructorArgumentValues().addIndexedArgumentValue(1, csInterceptorDef);
String mappedInterceptorName = parserContext.getReaderContext().registerWithGeneratedName(mappedCsInterceptorDef);
// ExceptionHandlerExceptionResolver RootBeanDefinition
RootBeanDefinition exceptionHandlerExceptionResolver = new RootBeanDefinition(ExceptionHandlerExceptionResolver.class);
exceptionHandlerExceptionResolver.setSource(source);
exceptionHandlerExceptionResolver.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
exceptionHandlerExceptionResolver.getPropertyValues().add("contentNegotiationManager", contentNegotiationManager);
exceptionHandlerExceptionResolver.getPropertyValues().add("messageConverters", messageConverters);
exceptionHandlerExceptionResolver.getPropertyValues().add("order", 0);
String methodExceptionResolverName =
parserContext.getReaderContext().registerWithGeneratedName(exceptionHandlerExceptionResolver);
// ResponseStatusExceptionResolver RootBeanDefinition
RootBeanDefinition responseStatusExceptionResolver = new RootBeanDefinition(ResponseStatusExceptionResolver.class);
responseStatusExceptionResolver.setSource(source);
responseStatusExceptionResolver.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
responseStatusExceptionResolver.getPropertyValues().add("order", 1);
String responseStatusExceptionResolverName =
parserContext.getReaderContext().registerWithGeneratedName(responseStatusExceptionResolver);
// DefaultHandlerExceptionResolver RootBeanDefinition
RootBeanDefinition defaultExceptionResolver = new RootBeanDefinition(DefaultHandlerExceptionResolver.class);
defaultExceptionResolver.setSource(source);
defaultExceptionResolver.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
defaultExceptionResolver.getPropertyValues().add("order", 2);
String defaultExceptionResolverName =
parserContext.getReaderContext().registerWithGeneratedName(defaultExceptionResolver);
parserContext.registerComponent(new BeanComponentDefinition(handlerMappingDef, methodMappingName));
parserContext.registerComponent(new BeanComponentDefinition(handlerAdapterDef, handlerAdapterName));
parserContext.registerComponent(new BeanComponentDefinition(exceptionHandlerExceptionResolver, methodExceptionResolverName));
parserContext.registerComponent(new BeanComponentDefinition(responseStatusExceptionResolver, responseStatusExceptionResolverName));
parserContext.registerComponent(new BeanComponentDefinition(defaultExceptionResolver, defaultExceptionResolverName));
parserContext.registerComponent(new BeanComponentDefinition(mappedCsInterceptorDef, mappedInterceptorName));
// Ensure BeanNameUrlHandlerMapping (SPR-8289) and default HandlerAdapters are not "turned off"
MvcNamespaceUtils.registerDefaultComponents(parserContext, source);
parserContext.popAndRegisterContainingComponent();
return null;
}
/** DefaultServletHandlerBeanDefinitionParser.java */
public BeanDefinition parse(Element element, ParserContext parserContext) {
Object source = parserContext.extractSource(element);
String defaultServletName = element.getAttribute("default-servlet-name");
// DefaultServletHttpRequestHandler RootBeanDefinition
RootBeanDefinition defaultServletHandlerDef = new RootBeanDefinition(DefaultServletHttpRequestHandler.class);
defaultServletHandlerDef.setSource(source);
defaultServletHandlerDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
if (StringUtils.hasText(defaultServletName)) {
defaultServletHandlerDef.getPropertyValues().add("defaultServletName", defaultServletName);
}
String defaultServletHandlerName = parserContext.getReaderContext().generateBeanName(defaultServletHandlerDef);
parserContext.getRegistry().registerBeanDefinition(defaultServletHandlerName, defaultServletHandlerDef);
parserContext.registerComponent(new BeanComponentDefinition(defaultServletHandlerDef, defaultServletHandlerName));
Map<String, String> urlMap = new ManagedMap<String, String>();
urlMap.put("/**", defaultServletHandlerName);
// SimpleUrlHandlerMapping RootBeanDefinition
RootBeanDefinition handlerMappingDef = new RootBeanDefinition(SimpleUrlHandlerMapping.class);
handlerMappingDef.setSource(source);
handlerMappingDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
handlerMappingDef.getPropertyValues().add("urlMap", urlMap);
String handlerMappingBeanName = parserContext.getReaderContext().generateBeanName(handlerMappingDef);
parserContext.getRegistry().registerBeanDefinition(handlerMappingBeanName, handlerMappingDef);
parserContext.registerComponent(new BeanComponentDefinition(handlerMappingDef, handlerMappingBeanName));
// Ensure BeanNameUrlHandlerMapping (SPR-8289) and default HandlerAdapters are not "turned off"
MvcNamespaceUtils.registerDefaultComponents(parserContext, source);
return null;
}
/** InterceptorsBeanDefinitionParser.java */
public BeanDefinition parse(Element element, ParserContext parserContext) {
CompositeComponentDefinition compDefinition = new CompositeComponentDefinition(element.getTagName(), parserContext.extractSource(element));
parserContext.pushContainingComponent(compDefinition);
List<Element> interceptors = DomUtils.getChildElementsByTagName(element, "bean", "ref", "interceptor");
for (Element interceptor : interceptors) {
// MappedInterceptor RootBeanDefinition
RootBeanDefinition mappedInterceptorDef = new RootBeanDefinition(MappedInterceptor.class);
mappedInterceptorDef.setSource(parserContext.extractSource(interceptor));
mappedInterceptorDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
ManagedList<String> includePatterns = null;
ManagedList<String> excludePatterns = null;
Object interceptorBean;
if ("interceptor".equals(interceptor.getLocalName())) {
includePatterns = getIncludePatterns(interceptor, "mapping");
excludePatterns = getIncludePatterns(interceptor, "exclude-mapping");
Element beanElem = DomUtils.getChildElementsByTagName(interceptor, "bean", "ref").get(0);
interceptorBean = parserContext.getDelegate().parsePropertySubElement(beanElem, null);
}
else {
interceptorBean = parserContext.getDelegate().parsePropertySubElement(interceptor, null);
}
mappedInterceptorDef.getConstructorArgumentValues().addIndexedArgumentValue(0, includePatterns);
mappedInterceptorDef.getConstructorArgumentValues().addIndexedArgumentValue(1, excludePatterns);
mappedInterceptorDef.getConstructorArgumentValues().addIndexedArgumentValue(2, interceptorBean);
String beanName = parserContext.getReaderContext().registerWithGeneratedName(mappedInterceptorDef);
parserContext.registerComponent(new BeanComponentDefinition(mappedInterceptorDef, beanName));
}
parserContext.popAndRegisterContainingComponent();
return null;
}
RequestMappingHandlerMapping bean初始化
RequestMappingHandlerMapping的初始化主要工作为建立请求url与HandlerMethod的映射关系。
AbstractHandlerMapping类结构关系图：
时序图：
相关源码：
/** AbstractHandlerMethodMapping.java */
protected void detectHandlerMethods(final Object handler) {
Class<?> handlerType =
(handler instanceof String ? getApplicationContext().getType((String) handler) : handler.getClass());
// Avoid repeated calls to getMappingForMethod which would rebuild RequestMatchingInfo instances
final Map<Method, T> mappings = new IdentityHashMap<Method, T>();
final Class<?> userType = ClassUtils.getUserClass(handlerType);
// 查找userType中带@RequestMapping注解的method
Set<Method> methods = HandlerMethodSelector.selectMethods(userType, new MethodFilter() {
public boolean matches(Method method) {
// 过滤带@RequestMapping注解的method，用@RequestMapping注解的属性值，new RequestMappingInfo
T mapping = getMappingForMethod(method, userType);
if (mapping != null) {
mappings.put(method, mapping);
return true;
}
else {
return false;
}
}
});
for (Method method : methods) {
//创建HandlerMethod且缓存其与url等的映射关系
registerHandlerMethod(handler, method, mappings.get(method));
}
}
/** RequestMappingHandlerMapping.java */
protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {
RequestMappingInfo info = null;
// method上的@RequestMapping注解对象
RequestMapping methodAnnotation = AnnotationUtils.findAnnotation(method, RequestMapping.class);
if (methodAnnotation != null) {
RequestCondition<?> methodCondition = getCustomMethodCondition(method);
info = createRequestMappingInfo(methodAnnotation, methodCondition);
// Class上的@RequestMapping注解对象
RequestMapping typeAnnotation = AnnotationUtils.findAnnotation(handlerType, RequestMapping.class);
if (typeAnnotation != null) {
RequestCondition<?> typeCondition = getCustomTypeCondition(handlerType);
// 相关属性合并
info = createRequestMappingInfo(typeAnnotation, typeCondition).combine(info);
}
}
return info;
}
/** AbstractHandlerMethodMapping.java */
protected void registerHandlerMethod(Object handler, Method method, T mapping) {
//创建HandlerMethod
HandlerMethod newHandlerMethod = createHandlerMethod(handler, method);
HandlerMethod oldHandlerMethod = this.handlerMethods.get(mapping);
if (oldHandlerMethod != null && !oldHandlerMethod.equals(newHandlerMethod)) {
throw new IllegalStateException("Ambiguous mapping found. Cannot map '" + newHandlerMethod.getBean() +
"' bean method \n" + newHandlerMethod + "\nto " + mapping + ": There is already '" +
oldHandlerMethod.getBean() + "' bean method\n" + oldHandlerMethod + " mapped.");
}
//RequestMappingInfo到HandlerMethod映射
this.handlerMethods.put(mapping, newHandlerMethod);
if (logger.isInfoEnabled()) {
logger.info("Mapped \"" + mapping + "\" onto " + newHandlerMethod);
}
Set<String> patterns = getMappingPathPatterns(mapping);
for (String pattern : patterns) {
if (!getPathMatcher().isPattern(pattern)) {
// url到RequestMappingInfo映射
this.urlMap.add(pattern, mapping);
}
}
}
protected HandlerMethod createHandlerMethod(Object handler, Method method) {
HandlerMethod handlerMethod;
if (handler instanceof String) {
String beanName = (String) handler;
handlerMethod = new HandlerMethod(beanName, getApplicationContext(), method);
}
else {
handlerMethod = new HandlerMethod(handler, method);
}
return handlerMethod;
}
/** RequestMappingInfoHandlerMapping.java */
protected Set<String> getMappingPathPatterns(RequestMappingInfo info) {
return info.getPatternsCondition().getPatterns();
}
一次http请求处理流程
整体流程
getHandler流程
时序图：
相关源码：
/** AbstractHandlerMethodMapping.java */
protected HandlerMethod lookupHandlerMethod(String lookupPath, HttpServletRequest request) throws Exception {
List<Match> matches = new ArrayList<Match>();
// 根据url获取RequestMappingInfo
List<T> directPathMatches = this.urlMap.get(lookupPath);
if (directPathMatches != null) {
// 匹配request的RequestMappingInfo
addMatchingMappings(directPathMatches, matches, request);
}
if (matches.isEmpty()) {
// No choice but to go through all mappings...
addMatchingMappings(this.handlerMethods.keySet(), matches, request);
}
if (!matches.isEmpty()) {
Comparator<Match> comparator = new MatchComparator(getMappingComparator(request));
Collections.sort(matches, comparator);
if (logger.isTraceEnabled()) {
logger.trace("Found " + matches.size() + " matching mapping(s) for [" + lookupPath + "] : " + matches);
}
// 最佳匹配request的Match
Match bestMatch = matches.get(0);
if (matches.size() > 1) {
Match secondBestMatch = matches.get(1);
if (comparator.compare(bestMatch, secondBestMatch) == 0) {
Method m1 = bestMatch.handlerMethod.getMethod();
Method m2 = secondBestMatch.handlerMethod.getMethod();
throw new IllegalStateException(
"Ambiguous handler methods mapped for HTTP path '" + request.getRequestURL() + "': {" +
m1 + ", " + m2 + "}");
}
}
handleMatch(bestMatch.mapping, lookupPath, request);
// 最佳匹配request的handlerMethod
return bestMatch.handlerMethod;
}
else {
return handleNoMatch(handlerMethods.keySet(), lookupPath, request);
}
}
private void addMatchingMappings(Collection<T> mappings, List<Match> matches, HttpServletRequest request) {
for (T mapping : mappings) {
// 根据request，获取匹配的RequestMappingInfo
T match = getMatchingMapping(mapping, request);
if (match != null) {
matches.add(new Match(match, this.handlerMethods.get(mapping)));
}
}
}
/** RequestMappingInfoHandlerMapping.java */
protected RequestMappingInfo getMatchingMapping(RequestMappingInfo info, HttpServletRequest request) {
return info.getMatchingCondition(request);
}
/** RequestMappingInfo.java */
// 根据request，获取匹配的RequestMappingInfo
public RequestMappingInfo getMatchingCondition(HttpServletRequest request) {
RequestMethodsRequestCondition methods = this.methodsCondition.getMatchingCondition(request);
ParamsRequestCondition params = this.paramsCondition.getMatchingCondition(request);
HeadersRequestCondition headers = this.headersCondition.getMatchingCondition(request);
ConsumesRequestCondition consumes = this.consumesCondition.getMatchingCondition(request);
ProducesRequestCondition produces = this.producesCondition.getMatchingCondition(request);
if (methods == null || params == null || headers == null || consumes == null || produces == null) {
return null;
}
PatternsRequestCondition patterns = this.patternsCondition.getMatchingCondition(request);
if (patterns == null) {
return null;
}
RequestConditionHolder custom = this.customConditionHolder.getMatchingCondition(request);
if (custom == null) {
return null;
}
return new RequestMappingInfo(patterns, methods, params, headers, consumes, produces, custom.getCondition());
}
/** RequestMappingInfoHandlerMapping.java */
protected void handleMatch(RequestMappingInfo info, String lookupPath, HttpServletRequest request) {
// request设置org.springframework.web.servlet.HandlerMapping.pathWithinHandlerMapping属性
super.handleMatch(info, lookupPath, request);
String bestPattern;
Map<String, String> uriVariables;
Map<String, String> decodedUriVariables;
Set<String> patterns = info.getPatternsCondition().getPatterns();
if (patterns.isEmpty()) {
bestPattern = lookupPath;
uriVariables = Collections.emptyMap();
decodedUriVariables = Collections.emptyMap();
}
else {
bestPattern = patterns.iterator().next();
uriVariables = getPathMatcher().extractUriTemplateVariables(bestPattern, lookupPath);
decodedUriVariables = getUrlPathHelper().decodePathVariables(request, uriVariables);
}
// request设置org.springframework.web.servlet.HandlerMapping.bestMatchingPattern属性
request.setAttribute(BEST_MATCHING_PATTERN_ATTRIBUTE, bestPattern);
// request设置org.springframework.web.servlet.HandlerMapping.uriTemplateVariables属性
request.setAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, decodedUriVariables);
if (isMatrixVariableContentAvailable()) {
Map<String, MultiValueMap<String, String>> matrixVars = extractMatrixVariables(request, uriVariables);
request.setAttribute(HandlerMapping.MATRIX_VARIABLES_ATTRIBUTE, matrixVars);
}
if (!info.getProducesCondition().getProducibleMediaTypes().isEmpty()) {
Set<MediaType> mediaTypes = info.getProducesCondition().getProducibleMediaTypes();
request.setAttribute(PRODUCIBLE_MEDIA_TYPES_ATTRIBUTE, mediaTypes);
}
}
/** AbstractHandlerMapping.java */
// 创建执行请求的处理链HandlerExecutionChain（拦截器+HandlerMethod）
protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) {
HandlerExecutionChain chain = (handler instanceof HandlerExecutionChain ?
(HandlerExecutionChain) handler : new HandlerExecutionChain(handler));
chain.addInterceptors(getAdaptedInterceptors());
String lookupPath = this.urlPathHelper.getLookupPathForRequest(request);
// 根据请求的lookupPath，获取匹配该url的拦截器
for (MappedInterceptor mappedInterceptor : this.mappedInterceptors) {
if (mappedInterceptor.matches(lookupPath, this.pathMatcher)) {
chain.addInterceptor(mappedInterceptor.getInterceptor());
}
}
return chain;
}
getHandlerAdapter流程
/** DispatcherServlet.java */
protected HandlerAdapter getHandlerAdapter(Object handler) throws ServletException {
for (HandlerAdapter ha : this.handlerAdapters) {
if (logger.isTraceEnabled()) {
logger.trace("Testing handler adapter [" + ha + "]");
}
if (ha.supports(handler)) {
return ha;
}
}
throw new ServletException("No adapter for handler [" + handler +
"]: The DispatcherServlet configuration needs to include a HandlerAdapter that supports this handler");
}
HandlerAdapter handle流程
HandlerAdapter类结构关系图：
时序图：
相关源码：
/** RequestMappingHandlerAdapter.java */
// 调用HandlerMethod返回结果ModelAndView
private ModelAndView invokeHandleMethod(HttpServletRequest request,
HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
ServletWebRequest webRequest = new ServletWebRequest(request, response);
//数据绑定Factory
WebDataBinderFactory binderFactory = getDataBinderFactory(handlerMethod);
ModelFactory modelFactory = getModelFactory(handlerMethod, binderFactory);
ServletInvocableHandlerMethod requestMappingMethod = createRequestMappingMethod(handlerMethod, binderFactory);
//缓存调用结果Model、View
ModelAndViewContainer mavContainer = new ModelAndViewContainer();
mavContainer.addAllAttributes(RequestContextUtils.getInputFlashMap(request));
modelFactory.initModel(webRequest, mavContainer, requestMappingMethod);
mavContainer.setIgnoreDefaultModelOnRedirect(this.ignoreDefaultModelOnRedirect);
AsyncWebRequest asyncWebRequest = WebAsyncUtils.createAsyncWebRequest(request, response);
asyncWebRequest.setTimeout(this.asyncRequestTimeout);
final 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();
if (logger.isDebugEnabled()) {
logger.debug("Found concurrent result value [" + result + "]");
}
requestMappingMethod = requestMappingMethod.wrapConcurrentResult(result);
}
// 调用HandlerMethod，且处理返回结果到mavContainer
requestMappingMethod.invokeAndHandle(webRequest, mavContainer);
if (asyncManager.isConcurrentHandlingStarted()) {
return null;
}
// 从mavContainer获取ModelAndView
return getModelAndView(mavContainer, modelFactory, webRequest);
}
/** ServletInvocableHandlerMethod.java */
public final void invokeAndHandle(ServletWebRequest webRequest,
ModelAndViewContainer mavContainer, Object... providedArgs) throws Exception {
// 调用HandlerMethod
Object returnValue = invokeForRequest(webRequest, mavContainer, providedArgs);
setResponseStatus(webRequest);
if (returnValue == null) {
if (isRequestNotModified(webRequest) || hasResponseStatus() || mavContainer.isRequestHandled()) {
mavContainer.setRequestHandled(true);
return;
}
}
else if (StringUtils.hasText(this.responseReason)) {
mavContainer.setRequestHandled(true);
return;
}
mavContainer.setRequestHandled(false);
try {
// 处理returnValue，将结果ModelAndView中的ModelMap键值对合并到mavContainer
this.returnValueHandlers.handleReturnValue(returnValue, getReturnValueType(returnValue), mavContainer, webRequest);
}
catch (Exception ex) {
if (logger.isTraceEnabled()) {
logger.trace(getReturnValueHandlingErrorMessage("Error handling return value", returnValue), ex);
}
throw ex;
}
}
/** InvocableHandlerMethod.java */
// 实际调用HandlerMethod
public final Object invokeForRequest(NativeWebRequest request, ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
// 获取HandlerMethod参数值
Object[] args = getMethodArgumentValues(request, mavContainer, providedArgs);
if (logger.isTraceEnabled()) {
StringBuilder sb = new StringBuilder("Invoking [");
sb.append(getBeanType().getSimpleName()).append(".");
sb.append(getMethod().getName()).append("] method with arguments ");
sb.append(Arrays.asList(args));
logger.trace(sb.toString());
}
// 利用反射实际调用HandlerMethod
Object returnValue = invoke(args);
if (logger.isTraceEnabled()) {
logger.trace("Method [" + getMethod().getName() + "] returned [" + returnValue + "]");
}
return returnValue;
}
private Object invoke(Object... args) throws Exception {
ReflectionUtils.makeAccessible(getBridgedMethod());
try {
return getBridgedMethod().invoke(getBean(), args);
}
catch (IllegalArgumentException ex) {
assertTargetBean(getBridgedMethod(), getBean(), args);
throw new IllegalStateException(getInvocationErrorMessage(ex.getMessage(), args), ex);
}
catch (InvocationTargetException ex) {
// Unwrap for HandlerExceptionResolvers ...
Throwable targetException = ex.getTargetException();
if (targetException instanceof RuntimeException) {
throw (RuntimeException) targetException;
}
else if (targetException instanceof Error) {
throw (Error) targetException;
}
else if (targetException instanceof Exception) {
throw (Exception) targetException;
}
else {
String msg = getInvocationErrorMessage("Failed to invoke controller method", args);
throw new IllegalStateException(msg, targetException);
}
}
}
/** HandlerMethodReturnValueHandlerComposite.java */
public void handleReturnValue(
Object returnValue, MethodParameter returnType,
ModelAndViewContainer mavContainer, NativeWebRequest webRequest)
throws Exception {
// 获取ReturnValueHandler
HandlerMethodReturnValueHandler handler = getReturnValueHandler(returnType);
Assert.notNull(handler, "Unknown return value type [" + returnType.getParameterType().getName() + "]");
// 处理ReturnValue
handler.handleReturnValue(returnValue, returnType, mavContainer, webRequest);
}
/** ModelAndViewMethodReturnValueHandler.java */
public void handleReturnValue(
Object returnValue, MethodParameter returnType,
ModelAndViewContainer mavContainer, NativeWebRequest webRequest)
throws Exception {
if (returnValue == null) {
mavContainer.setRequestHandled(true);
return;
}
ModelAndView mav = (ModelAndView) returnValue;
// viewName带"redirect:"则设置redirectModelScenario为true
if (mav.isReference()) {
String viewName = mav.getViewName();
mavContainer.setViewName(viewName);
if (viewName != null && viewName.startsWith("redirect:")) {
mavContainer.setRedirectModelScenario(true);
}
}
else {
View view = mav.getView();
mavContainer.setView(view);
if (view instanceof SmartView) {
if (((SmartView) view).isRedirectView()) {
mavContainer.setRedirectModelScenario(true);
}
}
}
// mav中的ModelMap的属性键值对合并到mavContainer
mavContainer.addAllAttributes(mav.getModel());
}
/** RequestMappingHandlerAdapter.java */
// 从mavContainer提取ModelAndView
private ModelAndView getModelAndView(ModelAndViewContainer mavContainer,
ModelFactory modelFactory, NativeWebRequest webRequest) throws Exception {
modelFactory.updateModel(webRequest, mavContainer);
if (mavContainer.isRequestHandled()) {
return null;
}
ModelMap model = mavContainer.getModel();
ModelAndView mav = new ModelAndView(mavContainer.getViewName(), model);
if (!mavContainer.isViewReference()) {
mav.setView((View) mavContainer.getView());
}
if (model instanceof RedirectAttributes) {
Map<String, ?> flashAttributes = ((RedirectAttributes) model).getFlashAttributes();
HttpServletRequest request = webRequest.getNativeRequest(HttpServletRequest.class);
RequestContextUtils.getOutputFlashMap(request).putAll(flashAttributes);
}
return mav;
}
processDispatchResult流程
/** DispatcherServlet.java */
private void processDispatchResult(HttpServletRequest request, HttpServletResponse response,
HandlerExecutionChain mappedHandler, ModelAndView mv, Exception exception) throws Exception {
boolean errorView = false;
if (exception != null) {
if (exception instanceof ModelAndViewDefiningException) {
logger.debug("ModelAndViewDefiningException encountered", exception);
mv = ((ModelAndViewDefiningException) exception).getModelAndView();
}
else {
Object handler = (mappedHandler != null ? mappedHandler.getHandler() : null);
mv = processHandlerException(request, response, handler, exception);
errorView = (mv != null);
}
}
// Did the handler return a view to render?
if (mv != null && !mv.wasCleared()) {
// 完成model到view的渲染，返回给前端
render(mv, request, response);
if (errorView) {
WebUtils.clearErrorRequestAttributes(request);
}
}
else {
if (logger.isDebugEnabled()) {
logger.debug("Null ModelAndView returned to DispatcherServlet with name '" + getServletName() +
"': assuming HandlerAdapter completed request handling");
}
}
if (WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) {
// Concurrent handling started during a forward
return;
}
if (mappedHandler != null) {
// 调用拦截器链afterCompletion方法
mappedHandler.triggerAfterCompletion(request, response, null);
}
}
protected void render(ModelAndView mv, HttpServletRequest request, HttpServletResponse response) throws Exception {
// 确定Locale语言zh_CN
Locale locale = this.localeResolver.resolveLocale(request);
response.setLocale(locale);
View view;
if (mv.isReference()) {
// 根据viewName，借助viewResolver解析，获取view
view = resolveViewName(mv.getViewName(), mv.getModelInternal(), locale, request);
if (view == null) {
throw new ServletException("Could not resolve view with name '" + mv.getViewName() +
"' in servlet with name '" + getServletName() + "'");
}
}
else {
// No need to lookup: the ModelAndView object contains the actual View object.
view = mv.getView();
if (view == null) {
throw new ServletException("ModelAndView [" + mv + "] neither contains a view name nor a " +
"View object in servlet with name '" + getServletName() + "'");
}
}
// Delegate to the View object for rendering.
if (logger.isDebugEnabled()) {
logger.debug("Rendering view [" + view + "] in DispatcherServlet with name '" + getServletName() + "'");
}
try {
// 将model中的键值对输出到request，利用RequestDispatcher渲染到jsp等前端页面上
view.render(mv.getModelInternal(), request, response);
}
catch (Exception ex) {
if (logger.isDebugEnabled()) {
logger.debug("Error rendering view [" + view + "] in DispatcherServlet with name '" +
getServletName() + "'", ex);
}
throw ex;
}
}
protected View resolveViewName(String viewName, Map<String, Object> model, Locale locale,
HttpServletRequest request) throws Exception {
for (ViewResolver viewResolver : this.viewResolvers) {
// viewResolver确定view
View view = viewResolver.resolveViewName(viewName, locale);
if (view != null) {
return view;
}
}
return null;
}
/** AbstractCachingViewResolver.java(InternalResourceViewResolver.java) */
public View resolveViewName(String viewName, Locale locale) throws Exception {
if (!isCache()) {
return createView(viewName, locale);
}
else {
Object cacheKey = getCacheKey(viewName, locale);
View view = this.viewAccessCache.get(cacheKey);
if (view == null) {
synchronized (this.viewCreationCache) {
view = this.viewCreationCache.get(cacheKey);
if (view == null) {
// 创建view
view = createView(viewName, locale);
if (view == null && this.cacheUnresolved) {
view = UNRESOLVED_VIEW;
}
if (view != null) {
// 缓存view
this.viewAccessCache.put(cacheKey, view);
this.viewCreationCache.put(cacheKey, view);
if (logger.isTraceEnabled()) {
logger.trace("Cached view [" + cacheKey + "]");
}
}
}
}
}
return (view != UNRESOLVED_VIEW ? view : null);
}
}
/** UrlBasedViewResolver.java(InternalResourceViewResolver.java) */
protected View createView(String viewName, Locale locale) throws Exception {
// If this resolver is not supposed to handle the given view,
// return null to pass on to the next resolver in the chain.
if (!canHandle(viewName, locale)) {
return null;
}
// viewName前缀为"redirect:"，创建RedirectView
if (viewName.startsWith(REDIRECT_URL_PREFIX)) {
String redirectUrl = viewName.substring(REDIRECT_URL_PREFIX.length());
RedirectView view = new RedirectView(redirectUrl, isRedirectContextRelative(), isRedirectHttp10Compatible());
return applyLifecycleMethods(viewName, view);
}
// viewName前缀为"forward:"，创建InternalResourceView
if (viewName.startsWith(FORWARD_URL_PREFIX)) {
String forwardUrl = viewName.substring(FORWARD_URL_PREFIX.length());
return new InternalResourceView(forwardUrl);
}
// 直接创建View
return super.createView(viewName, locale);
}
protected View loadView(String viewName, Locale locale) throws Exception {
// 创建view
AbstractUrlBasedView view = buildView(viewName);
// 初始化view bean
View result = applyLifecycleMethods(viewName, view);
return (view.checkResource(locale) ? result : null);
}
private View applyLifecycleMethods(String viewName, AbstractView view) {
return (View) getApplicationContext().getAutowireCapableBeanFactory().initializeBean(view, viewName);
}
/** InternalResourceViewResolver.java */
protected AbstractUrlBasedView buildView(String viewName) throws Exception {
InternalResourceView view = (InternalResourceView) super.buildView(viewName);
if (this.alwaysInclude != null) {
view.setAlwaysInclude(this.alwaysInclude);
}
if (this.exposeContextBeansAsAttributes != null) {
view.setExposeContextBeansAsAttributes(this.exposeContextBeansAsAttributes);
}
if (this.exposedContextBeanNames != null) {
view.setExposedContextBeanNames(this.exposedContextBeanNames);
}
view.setPreventDispatchLoop(true);
return view;
}
/** UrlBasedViewResolver.java(InternalResourceViewResolver.java) */
protected AbstractUrlBasedView buildView(String viewName) throws Exception {
// 用反射实例化view
AbstractUrlBasedView view = (AbstractUrlBasedView) BeanUtils.instantiateClass(getViewClass());
// 设置view对应的url，例如/WEB-INF/pages/index.jsp
view.setUrl(getPrefix() + viewName + getSuffix());
String contentType = getContentType();
if (contentType != null) {
view.setContentType(contentType);
}
view.setRequestContextAttribute(getRequestContextAttribute());
view.setAttributesMap(getAttributesMap());
if (this.exposePathVariables != null) {
view.setExposePathVariables(exposePathVariables);
}
return view;
}
/** AbstractView.java(JstlView.java) */
public void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
if (logger.isTraceEnabled()) {
logger.trace("Rendering view with name '" + this.beanName + "' with model " + model +
" and static attributes " + this.staticAttributes);
}
// 合并model中的键值对
Map<String, Object> mergedModel = createMergedOutputModel(model, request, response);
prepareResponse(request, response);
renderMergedOutputModel(mergedModel, request, response);
}
protected Map<String, Object> createMergedOutputModel(Map<String, ?> model, HttpServletRequest request,
HttpServletResponse response) {
@SuppressWarnings("unchecked")
Map<String, Object> pathVars = (this.exposePathVariables ?
(Map<String, Object>) request.getAttribute(View.PATH_VARIABLES) : null);
// Consolidate static and dynamic model attributes.
int size = this.staticAttributes.size();
size += (model != null) ? model.size() : 0;
size += (pathVars != null) ? pathVars.size() : 0;
Map<String, Object> mergedModel = new LinkedHashMap<String, Object>(size);
mergedModel.putAll(this.staticAttributes);
if (pathVars != null) {
mergedModel.putAll(pathVars);
}
if (model != null) {
mergedModel.putAll(model);
}
// Expose RequestContext?
if (this.requestContextAttribute != null) {
mergedModel.put(this.requestContextAttribute, createRequestContext(request, response, mergedModel));
}
return mergedModel;
}
/** InternalResourceView.java(JstlView.java) */
protected void renderMergedOutputModel(
Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
// Determine which request handle to expose to the RequestDispatcher.
HttpServletRequest requestToExpose = getRequestToExpose(request);
// 将model中的键值对输出到request，做为request的Attribute
exposeModelAsRequestAttributes(model, requestToExpose);
// 在request属性中设置LocalizationContext键值对
exposeHelpers(requestToExpose);
// 确定request dispatcher的url
String dispatcherPath = prepareForRendering(requestToExpose, response);
// 获取RequestDispatcher
RequestDispatcher rd = getRequestDispatcher(requestToExpose, dispatcherPath);
if (rd == null) {
throw new ServletException("Could not get RequestDispatcher for [" + getUrl() +
"]: Check that the corresponding file exists within your web application archive!");
}
// 完成model到view的渲染，返回给前端
// If already included or response already committed, perform include, else forward.
if (useInclude(requestToExpose, response)) {
response.setContentType(getContentType());
if (logger.isDebugEnabled()) {
logger.debug("Including resource [" + getUrl() + "] in InternalResourceView '" + getBeanName() + "'");
}
rd.include(requestToExpose, response);
}
else {
// Note: The forwarded resource is supposed to determine the content type itself.
exposeForwardRequestAttributes(requestToExpose);
if (logger.isDebugEnabled()) {
logger.debug("Forwarding to resource [" + getUrl() + "] in InternalResourceView '" + getBeanName() + "'");
}
rd.forward(requestToExpose, response);
}
}
/** AbstractView.java(JstlView.java) */
protected void exposeModelAsRequestAttributes(Map<String, Object> model, HttpServletRequest request) throws Exception {
for (Map.Entry<String, Object> entry : model.entrySet()) {
String modelName = entry.getKey();
Object modelValue = entry.getValue();
if (modelValue != null) {
request.setAttribute(modelName, modelValue);
if (logger.isDebugEnabled()) {
logger.debug("Added model object '" + modelName + "' of type [" + modelValue.getClass().getName() +
"] to request in view with name '" + getBeanName() + "'");
}
}
else {
request.removeAttribute(modelName);
if (logger.isDebugEnabled()) {
logger.debug("Removed model object '" + modelName +
"' from request in view with name '" + getBeanName() + "'");
}
}
}
}
/** InternalResourceView.java(JstlView.java) */
protected String prepareForRendering(HttpServletRequest request, HttpServletResponse response)
throws Exception {
String path = getUrl();
if (this.preventDispatchLoop) {
String uri = request.getRequestURI();
if (path.startsWith("/") ? uri.equals(path) : uri.equals(StringUtils.applyRelativePath(uri, path))) {
throw new ServletException("Circular view path [" + path + "]: would dispatch back " +
"to the current handler URL [" + uri + "] again. Check your ViewResolver setup! " +
"(Hint: This may be the result of an unspecified view, due to default view name generation.)");
}
}
return path;
}
protected RequestDispatcher getRequestDispatcher(HttpServletRequest request, String path) {
return request.getRequestDispatcher(path);
}
参考
http://jinnianshilongnian.iteye.com/blog/1594806
相关资源：看透springMvc源代码分析与实践.pdf
