springmvc源码解析之DispatcherServlet一
说在前面java
本次主要介绍DispatcherServlet组件，更多精彩请关注”天河聊架构“微信公众号。ios
springmvc配置解析web
进入到这个方法org.springframework.web.servlet.FrameworkServlet#servicespring
@Override
protected void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
HttpMethod httpMethod = HttpMethod.resolve(request.getMethod());
if (httpMethod == HttpMethod.PATCH || httpMethod == null) {
// 执行request请求
processRequest(request, response);
}
else {
super.service(request, response);
}
}
进入到这个方法org.springframework.web.servlet.FrameworkServlet#processRequest跨域
protected final void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
long startTime = System.currentTimeMillis();
Throwable failureCause = null;
LocaleContext previousLocaleContext = LocaleContextHolder.getLocaleContext();
LocaleContext localeContext = buildLocaleContext(request);
// 获取请求绑定属性 -》
RequestAttributes previousAttributes = RequestContextHolder.getRequestAttributes();
ServletRequestAttributes requestAttributes = buildRequestAttributes(request, response, previousAttributes);
// 获取异步请求管理器 -》
WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
// 注册callable返回值拦截器
asyncManager.registerCallableInterceptor(FrameworkServlet.class.getName(), new RequestBindingInterceptor());
// 初始化上下文
initContextHolders(request, localeContext, requestAttributes);
try {
// 执行request请求模板方法 -》
doService(request, response);
}
catch (ServletException ex) {
failureCause = ex;
throw ex;
}
catch (IOException ex) {
failureCause = ex;
throw ex;
}
catch (Throwable ex) {
failureCause = ex;
throw new NestedServletException("Request processing failed", ex);
}
finally {
resetContextHolders(request, previousLocaleContext, previousAttributes);
if (requestAttributes != null) {
// -》
requestAttributes.requestCompleted();
}
if (logger.isDebugEnabled()) {
if (failureCause != null) {
this.logger.debug("Could not complete request", failureCause);
}
else {
if (asyncManager.isConcurrentHandlingStarted()) {
logger.debug("Leaving response open for concurrent processing");
}
else {
this.logger.debug("Successfully completed request");
}
}
}
// 发布请求处理事件 -》
publishRequestHandledEvent(request, response, startTime, failureCause);
}
}
进入到这个方法org.springframework.web.context.request.RequestContextHolder#getRequestAttributes微信
public static RequestAttributes getRequestAttributes() {
RequestAttributes attributes = requestAttributesHolder.get();
if (attributes == null) {
attributes = inheritableRequestAttributesHolder.get();
}
return attributes;
}
往上返回到这个方法org.springframework.web.context.request.async.WebAsyncUtils#getAsyncManager(javax.servlet.ServletRequest)架构
public static WebAsyncManager getAsyncManager(ServletRequest servletRequest) {
WebAsyncManager asyncManager = null;
// 从request中获取请求管理器
Object asyncManagerAttr = servletRequest.getAttribute(WEB_ASYNC_MANAGER_ATTRIBUTE);
if (asyncManagerAttr instanceof WebAsyncManager) {
asyncManager = (WebAsyncManager) asyncManagerAttr;
}
// 若是没有就建立后绑定到request中
if (asyncManager == null) {
asyncManager = new WebAsyncManager();
servletRequest.setAttribute(WEB_ASYNC_MANAGER_ATTRIBUTE, asyncManager);
}
return asyncManager;
}
进入到这个方法org.springframework.web.servlet.DispatcherServlet#doServicemvc
@Override
protected void doService(HttpServletRequest request, HttpServletResponse response) throws Exception {
if (logger.isDebugEnabled()) {
String resumed = WebAsyncUtils.getAsyncManager(request).hasConcurrentResult() ? " resumed" : "";
logger.debug("DispatcherServlet with name '" + getServletName() + "'" + resumed +
" processing " + request.getMethod() + " request for [" + getRequestUri(request) + "]");
}
// Keep a snapshot of the request attributes in case of an include,保存请求属性的快照，以防包含，
// to be able to restore the original attributes after the include.才能恢复包含后的原始属性。
Map<String, Object> attributesSnapshot = null; //为include请求保存了一个参数map快照
// 若是是include请求
if (WebUtils.isIncludeRequest(request)) {
attributesSnapshot = new HashMap<String, Object>();
// 获取请求参数
Enumeration<?> attrNames = request.getAttributeNames();
while (attrNames.hasMoreElements()) {
String attrName = (String) attrNames.nextElement();
if (this.cleanupAfterInclude || attrName.startsWith(DEFAULT_STRATEGIES_PREFIX)) {
attributesSnapshot.put(attrName, request.getAttribute(attrName));
}
}
}
// Make framework objects available to handlers and view objects.使框架对象对处理程序和视图对象可用。
request.setAttribute(WEB_APPLICATION_CONTEXT_ATTRIBUTE, getWebApplicationContext());
request.setAttribute(LOCALE_RESOLVER_ATTRIBUTE, this.localeResolver);
request.setAttribute(THEME_RESOLVER_ATTRIBUTE, this.themeResolver);
request.setAttribute(THEME_SOURCE_ATTRIBUTE, getThemeSource());
FlashMap inputFlashMap = this.flashMapManager.retrieveAndUpdate(request, response);
if (inputFlashMap != null) {
request.setAttribute(INPUT_FLASH_MAP_ATTRIBUTE, Collections.unmodifiableMap(inputFlashMap));
}
request.setAttribute(OUTPUT_FLASH_MAP_ATTRIBUTE, new FlashMap());
request.setAttribute(FLASH_MAP_MANAGER_ATTRIBUTE, this.flashMapManager);
try {
// 请求转发 -》
doDispatch(request, response);
}
finally {
if (!WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) {
// Restore the original attribute snapshot, in case of an include.
if (attributesSnapshot != null) {
restoreAttributesAfterInclude(request, attributesSnapshot);
}
}
}
}
进入到这个方法org.springframework.web.servlet.DispatcherServlet#doDispatchapp
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
HttpServletRequest processedRequest = request;
HandlerExecutionChain mappedHandler = null;
boolean multipartRequestParsed = false;
// 获取异步请求管理器
WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
try {
ModelAndView mv = null;
Exception dispatchException = null;
try {
// 是不是上传文件请求 -》
processedRequest = checkMultipart(request);
multipartRequestParsed = (processedRequest != request);
// Determine handler for the current request. 获取请求的handler -》
mappedHandler = getHandler(processedRequest);
if (mappedHandler == null || mappedHandler.getHandler() == null) {
// 找不到handler报错 -》
noHandlerFound(processedRequest, response);
return;
}
// Determine handler adapter for the current request.肯定当前请求的处理程序适配器。-》
HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());
// Process last-modified header, if supported by the handler.
String method = request.getMethod();
boolean isGet = "GET".equals(method);
if (isGet || "HEAD".equals(method)) {
long lastModified = ha.getLastModified(request, mappedHandler.getHandler());
if (logger.isDebugEnabled()) {
logger.debug("Last-Modified value for [" + getRequestUri(request) + "] is: " + lastModified);
}
if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) {
return;
}
}
// 执行前置拦截器 -》
if (!mappedHandler.applyPreHandle(processedRequest, response)) {
return;
}
// Actually invoke the handler.执行handler -》
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
// 若是是异步直接返回
if (asyncManager.isConcurrentHandlingStarted()) {
return;
}
// 解析默认的视图
applyDefaultViewName(processedRequest, mv);
// 执行后置拦截器
mappedHandler.applyPostHandle(processedRequest, response, mv);
}
catch (Exception ex) {
dispatchException = ex;
}
catch (Throwable err) {
// As of 4.3, we're processing Errors thrown from handler methods as well,
// making them available for @ExceptionHandler methods and other scenarios.
dispatchException = new NestedServletException("Handler dispatch failed", err);
}
processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
}
catch (Exception ex) {
// 异常执行拦截器的完成事件
triggerAfterCompletion(processedRequest, response, mappedHandler, ex);
}
catch (Throwable err) {
triggerAfterCompletion(processedRequest, response, mappedHandler,
new NestedServletException("Handler processing failed", err));
}
finally {
if (asyncManager.isConcurrentHandlingStarted()) {
// Instead of postHandle and afterCompletion
if (mappedHandler != null) {
mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response);
}
}
else {
// Clean up any resources used by a multipart request.
if (multipartRequestParsed) {
cleanupMultipart(processedRequest);
}
}
}
}
进入到这个方法org.springframework.web.servlet.DispatcherServlet#checkMultipartcors
protected HttpServletRequest checkMultipart(HttpServletRequest request) throws MultipartException {
// 判断是不是上传文件请求 -》
if (this.multipartResolver != null && this.multipartResolver.isMultipart(request)) {
if (WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class) != null) {
logger.debug("Request is already a MultipartHttpServletRequest - if not in a forward, " +
"this typically results from an additional MultipartFilter in web.xml");
}
else if (hasMultipartException(request) ) {
logger.debug("Multipart resolution failed for current request before - " +
"skipping re-resolution for undisturbed error rendering");
}
else {
try {
// 解析文件上传 -》
return this.multipartResolver.resolveMultipart(request);
}
catch (MultipartException ex) {
if (request.getAttribute(WebUtils.ERROR_EXCEPTION_ATTRIBUTE) != null) {
logger.debug("Multipart resolution failed for error dispatch", ex);
// Keep processing error dispatch with regular request handle below
}
else {
throw ex;
}
}
}
}
// If not returned before: return original request.
return request;
}
进入到这个方法org.springframework.web.multipart.support.StandardServletMultipartResolver#isMultipart
@Override
public boolean isMultipart(HttpServletRequest request) {
// Same check as in Commons FileUpload... 若是不是post请求直接返回
if (!"post".equalsIgnoreCase(request.getMethod())) {
return false;
}
// 请求资源类型中是否包含multipart/
String contentType = request.getContentType();
return StringUtils.startsWithIgnoreCase(contentType, "multipart/");
}
这种是springmvc标准实现，另外一种是common uploiad实现。
往上返回到这个方法org.springframework.web.multipart.support.StandardServletMultipartResolver#resolveMultipart
@Override
public MultipartHttpServletRequest resolveMultipart(HttpServletRequest request) throws MultipartException {
return new StandardMultipartHttpServletRequest(request, this.resolveLazily);
}
这种是springmvc标准实现。
往上返回到这个方法org.springframework.web.multipart.commons.CommonsMultipartResolver#resolveMultipart
@Override
public MultipartHttpServletRequest resolveMultipart(final HttpServletRequest request) throws MultipartException {
Assert.notNull(request, "Request must not be null");
if (this.resolveLazily) {
return new DefaultMultipartHttpServletRequest(request) {
@Override
// 解析上传文件请求 -》
protected void initializeMultipart() {
MultipartParsingResult parsingResult = parseRequest(request);
setMultipartFiles(parsingResult.getMultipartFiles());
setMultipartParameters(parsingResult.getMultipartParameters());
setMultipartParameterContentTypes(parsingResult.getMultipartParameterContentTypes());
}
};
}
else {
MultipartParsingResult parsingResult = parseRequest(request);
return new DefaultMultipartHttpServletRequest(request, parsingResult.getMultipartFiles(),
parsingResult.getMultipartParameters(), parsingResult.getMultipartParameterContentTypes());
}
}
这种是common upload实现。
进入到这个方法org.springframework.web.multipart.commons.CommonsMultipartResolver#parseRequest
protected MultipartParsingResult parseRequest(HttpServletRequest request) throws MultipartException {
// 获取请求的编码 -》
String encoding = determineEncoding(request);
// 准备上传 -》
FileUpload fileUpload = prepareFileUpload(encoding);
try {
// 处理上传请求
List<FileItem> fileItems = ((ServletFileUpload) fileUpload).parseRequest(request);
// 解析上传文件
return parseFileItems(fileItems, encoding);
}
catch (FileUploadBase.SizeLimitExceededException ex) {
throw new MaxUploadSizeExceededException(fileUpload.getSizeMax(), ex);
}
catch (FileUploadBase.FileSizeLimitExceededException ex) {
throw new MaxUploadSizeExceededException(fileUpload.getFileSizeMax(), ex);
}
catch (FileUploadException ex) {
throw new MultipartException("Failed to parse multipart servlet request", ex);
}
}
进入到这个方法org.springframework.web.multipart.commons.CommonsMultipartResolver#determineEncoding
protected String determineEncoding(HttpServletRequest request) {
String encoding = request.getCharacterEncoding();
if (encoding == null) {
encoding = getDefaultEncoding();
}
return encoding;
}
往上返回到这个方法org.springframework.web.multipart.commons.CommonsFileUploadSupport#prepareFileUpload
protected FileUpload prepareFileUpload(String encoding) {
FileUpload fileUpload = getFileUpload();
FileUpload actualFileUpload = fileUpload;
// Use new temporary FileUpload instance if the request specifies 若是请求指定，则使用新的临时FileUpload实例
// its own encoding that does not match the default encoding.不匹配默认编码的自身编码。
if (encoding != null && !encoding.equals(fileUpload.getHeaderEncoding())) {
actualFileUpload = newFileUpload(getFileItemFactory());
actualFileUpload.setSizeMax(fileUpload.getSizeMax());
// 文件上传文件最大值
actualFileUpload.setFileSizeMax(fileUpload.getFileSizeMax());
actualFileUpload.setHeaderEncoding(encoding);
}
return actualFileUpload;
}
往上返回到这个方法org.springframework.web.servlet.DispatcherServlet#getHandler
protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
for (HandlerMapping hm : this.handlerMappings) {
if (logger.isTraceEnabled()) {
logger.trace(
"Testing handler map [" + hm + "] in DispatcherServlet with name '" + getServletName() + "'");
}
// 获取request的handler执行链 -》
HandlerExecutionChain handler = hm.getHandler(request);
if (handler != null) {
return handler;
}
}
return null;
}
进入到这个方法org.springframework.web.servlet.handler.AbstractHandlerMapping#getHandler
@Override
public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
// 根据请求找到hander -》
Object handler = getHandlerInternal(request);
if (handler == null) {
// 若是找不到handler就使用默认的handler
handler = getDefaultHandler();
}
if (handler == null) {
return null;
}
// Bean name or resolved handler?
if (handler instanceof String) {
String handlerName = (String) handler;
// 从上下文中获取handler
handler = getApplicationContext().getBean(handlerName);
}
// 根据handler和request获取执行链 拦截器和要执行的handler -》
HandlerExecutionChain executionChain = getHandlerExecutionChain(handler, request);
// 若是是跨域请求，header中有Origin -》
if (CorsUtils.isCorsRequest(request)) {
// 根据请求获取跨域配置信息 -》
CorsConfiguration globalConfig = this.globalCorsConfigSource.getCorsConfiguration(request);
// 根据handler和request获取跨域配置 -》
CorsConfiguration handlerConfig = getCorsConfiguration(handler, request);
CorsConfiguration config = (globalConfig != null ? globalConfig.combine(handlerConfig) : handlerConfig);
// 获取跨域请求的执行链 -》
executionChain = getCorsHandlerExecutionChain(request, executionChain, config);
}
return executionChain;
}
进入到这个方法org.springframework.web.servlet.handler.AbstractHandlerMethodMapping#getHandlerInternal
@Override
protected HandlerMethod getHandlerInternal(HttpServletRequest request) throws Exception {
// 根据请求路径匹配到业务hander方法的路径
String lookupPath = getUrlPathHelper().getLookupPathForRequest(request);
if (logger.isDebugEnabled()) {
logger.debug("Looking up handler method for path " + lookupPath);
}
this.mappingRegistry.acquireReadLock();
try {
// 匹配业务handler方法 -》
HandlerMethod handlerMethod = lookupHandlerMethod(lookupPath, request);
if (logger.isDebugEnabled()) {
if (handlerMethod != null) {
logger.debug("Returning handler method [" + handlerMethod + "]");
}
else {
logger.debug("Did not find handler method for [" + lookupPath + "]");
}
}
return (handlerMethod != null ? handlerMethod.createWithResolvedBean() : null);
}
finally {
this.mappingRegistry.releaseReadLock();
}
}
进入到这个方法org.springframework.web.util.UrlPathHelper#getLookupPathForRequest
public String getLookupPathForRequest(HttpServletRequest request) {
// Always use full path within current servlet context? 老是在当前servlet上下文中使用完整路径? -》
if (this.alwaysUseFullPath) {
return getPathWithinApplication(request);
}
// Else, use path within current servlet mapping if applicable 不然，在当前servlet映射中使用path(若是适用)
String rest = getPathWithinServletMapping(request);
if (!"".equals(rest)) {
return rest;
}
else {
return getPathWithinApplication(request);
}
}
进入到这个方法org.springframework.web.util.UrlPathHelper#getPathWithinApplication
public String getPathWithinApplication(HttpServletRequest request) {
// 获取servlet上下文路径 -》
String contextPath = getContextPath(request);
// 获取资源请求路径 -》
String requestUri = getRequestUri(request);
String path = getRemainingPath(requestUri, contextPath, true);
if (path != null) {
// Normal case: URI contains context path.
return (StringUtils.hasText(path) ? path : "/");
}
else {
return requestUri;
}
}
进入到这个方法org.springframework.web.util.UrlPathHelper#getContextPath
public String getContextPath(HttpServletRequest request) {
// 获取servlet上下文路径
String contextPath = (String) request.getAttribute(WebUtils.INCLUDE_CONTEXT_PATH_ATTRIBUTE);
if (contextPath == null) {
contextPath = request.getContextPath();
}
if ("/".equals(contextPath)) {
// Invalid case, but happens for includes on Jetty: silently adapt it.
contextPath = "";
}
// 解码请求 -》
return decodeRequestString(request, contextPath);
}
进入到这个方法org.springframework.web.util.UrlPathHelper#decodeRequestString
public String decodeRequestString(HttpServletRequest request, String source) {
if (this.urlDecode && source != null) {
// 标准解码 -》
return decodeInternal(request, source);
}
return source;
}
进入到这个方法org.springframework.web.util.UrlPathHelper#decodeInternal
private String decodeInternal(HttpServletRequest request, String source) {
// 从request中获取编码格式，若是没有采用ISO-8859-1编码 -》
String enc = determineEncoding(request);
try {
return UriUtils.decode(source, enc);
}
catch (UnsupportedEncodingException ex) {
if (logger.isWarnEnabled()) {
logger.warn("Could not decode request string [" + source + "] with encoding '" + enc +
"': falling back to platform default encoding; exception message: " + ex.getMessage());
}
return URLDecoder.decode(source);
}
}
进入到这个方法org.springframework.web.util.UrlPathHelper#determineEncoding
protected String determineEncoding(HttpServletRequest request) {
String enc = request.getCharacterEncoding();
if (enc == null) {
enc = getDefaultEncoding();
}
return enc;
}
往上返回到这个方法org.springframework.web.util.UrlPathHelper#getRequestUri
public String getRequestUri(HttpServletRequest request) {
// 从request中获取请求资源路径
String uri = (String) request.getAttribute(WebUtils.INCLUDE_REQUEST_URI_ATTRIBUTE);
if (uri == null) {
uri = request.getRequestURI();
}
return decodeAndCleanUriString(request, uri);
}
往上返回到这个方法org.springframework.web.servlet.handler.AbstractHandlerMethodMapping#lookupHandlerMethod
protected HandlerMethod lookupHandlerMethod(String lookupPath, HttpServletRequest request) throws Exception {
List<Match> matches = new ArrayList<Match>();
// 根据url查找映射
List<T> directPathMatches = this.mappingRegistry.getMappingsByUrl(lookupPath);
if (directPathMatches != null) {
// 添加匹配的映射 -》
addMatchingMappings(directPathMatches, matches, request);
}
if (matches.isEmpty()) {
// No choice but to go through all mappings...
addMatchingMappings(this.mappingRegistry.getMappings().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);
}
Match bestMatch = matches.get(0);
if (matches.size() > 1) {
if (CorsUtils.isPreFlightRequest(request)) {
return PREFLIGHT_AMBIGUOUS_MATCH;
}
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 + "}");
}
}
request.setAttribute(BEST_MATCHING_HANDLER_ATTRIBUTE, bestMatch.handlerMethod);
// hander匹配
handleMatch(bestMatch.mapping, lookupPath, request);
return bestMatch.handlerMethod;
}
else {
return handleNoMatch(this.mappingRegistry.getMappings().keySet(), lookupPath, request);
}
}
进入到这个方法org.springframework.web.servlet.handler.AbstractHandlerMethodMapping#addMatchingMappings
private void addMatchingMappings(Collection<T> mappings, List<Match> matches, HttpServletRequest request) {
for (T mapping : mappings) {
// 获取匹配的映射 -》
T match = getMatchingMapping(mapping, request);
if (match != null) {
matches.add(new Match(match, this.mappingRegistry.getMappings().get(mapping)));
}
}
}
进入到这个方法org.springframework.web.servlet.mvc.method.RequestMappingInfo#getMatchingCondition
@Override
public RequestMappingInfo getMatchingCondition(HttpServletRequest request) {
// 获取匹配的方法 -》
RequestMethodsRequestCondition methods = this.methodsCondition.getMatchingCondition(request);
// 参数匹配
ParamsRequestCondition params = this.paramsCondition.getMatchingCondition(request);
// headers匹配
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(this.name, patterns,
methods, params, headers, consumes, produces, custom.getCondition());
}
进入到这个方法org.springframework.web.servlet.mvc.condition.RequestMethodsRequestCondition#getMatchingCondition
@Override
public RequestMethodsRequestCondition getMatchingCondition(HttpServletRequest request) {
// 是否跨域 -》
if (CorsUtils.isPreFlightRequest(request)) {
// 跨域匹配 -》
return matchPreFlight(request);
}
if (getMethods().isEmpty()) {
if (RequestMethod.OPTIONS.name().equals(request.getMethod()) &&
!DispatcherType.ERROR.equals(request.getDispatcherType())) {
return null; // No implicit match for OPTIONS (we handle it)
}
return this;
}
return matchRequestMethod(request.getMethod());
}
进入到这个方法org.springframework.web.cors.CorsUtils#isPreFlightRequest
public static boolean isPreFlightRequest(HttpServletRequest request) {
return (isCorsRequest(request) && HttpMethod.OPTIONS.matches(request.getMethod()) &&
request.getHeader(HttpHeaders.ACCESS_CONTROL_REQUEST_METHOD) != null);
}
往上返回到这个方法org.springframework.web.servlet.mvc.condition.RequestMethodsRequestCondition#matchPreFlight
private RequestMethodsRequestCondition matchPreFlight(HttpServletRequest request) {
if (getMethods().isEmpty()) {
return this;
}
String expectedMethod = request.getHeader(HttpHeaders.ACCESS_CONTROL_REQUEST_METHOD);
// 匹配请求方法-》
return matchRequestMethod(expectedMethod);
}
进入到这个方法org.springframework.web.servlet.mvc.condition.RequestMethodsRequestCondition#matchRequestMethod
private RequestMethodsRequestCondition matchRequestMethod(String httpMethodValue) {
HttpMethod httpMethod = HttpMethod.resolve(httpMethodValue);
if (httpMethod != null) {
for (RequestMethod method : getMethods()) {
if (httpMethod.matches(method.name())) {
return new RequestMethodsRequestCondition(method);
}
}
if (httpMethod == HttpMethod.HEAD && getMethods().contains(RequestMethod.GET)) {
return GET_CONDITION;
}
}
return null;
}
往上返回到这个方法org.springframework.web.servlet.handler.AbstractHandlerMapping#getHandlerExecutionChain
说到最后
本次源码解析仅表明我的观点，仅供参考。
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