说在前面
本次主要介绍DispatcherServlet，关注”天河聊架构“更多精彩。
springmvc配置解析
进入方法org.springframework.web.bind.annotation.support.HandlerMethodInvoker#resolveHttpEntityRequest
private HttpEntity<?> resolveHttpEntityRequest(MethodParameter methodParam, NativeWebRequest webRequest)
throws Exception {
HttpInputMessage inputMessage = createHttpInputMessage(webRequest);
Class<?> paramType = getHttpEntityType(methodParam);
Object body = readWithMessageConverters(methodParam, inputMessage, paramType);
return new HttpEntity<Object>(body, inputMessage.getHeaders());
}返回方法org.springframework.web.bind.annotation.support.HandlerMethodInvoker#resolveRequestParam
private Object resolveRequestParam(String paramName, boolean required, String defaultValue,
MethodParameter methodParam, NativeWebRequest webRequest, Object handlerForInitBinderCall)
throws Exception {
Class<?> paramType = methodParam.getParameterType();
if (Map.class.isAssignableFrom(paramType) && paramName.length() == 0) {
return resolveRequestParamMap((Class<? extends Map<?, ?>>) paramType, webRequest);
}
if (paramName.length() == 0) {
paramName = getRequiredParameterName(methodParam);
}
Object paramValue = null;
// 解析上传文件的属性名
MultipartRequest multipartRequest = webRequest.getNativeRequest(MultipartRequest.class);
if (multipartRequest != null) {
List<MultipartFile> files = multipartRequest.getFiles(paramName);
if (!files.isEmpty()) {
paramValue = (files.size() == 1 ? files.get(0) : files);
}
}
if (paramValue == null) {
// 底层还是调用request.getParameterValues方法
String[] paramValues = webRequest.getParameterValues(paramName);
if (paramValues != null) {
paramValue = (paramValues.length == 1 ? paramValues[0] : paramValues);
}
}
// 赋默认值
if (paramValue == null) {
if (defaultValue != null) {
paramValue = resolveDefaultValue(defaultValue);
}
// 如果是必填值就抛异常
else if (required) {
raiseMissingParameterException(paramName, paramType);
}
paramValue = checkValue(paramName, paramValue, paramType);
}
// 创建属性绑定器
WebDataBinder binder = createBinder(webRequest, null, paramName);
// 初始化参数绑定 -》
initBinder(handlerForInitBinderCall, paramName, binder, webRequest);
return binder.convertIfNecessary(paramValue, paramType, methodParam);
}进入方法org.springframework.web.bind.annotation.support.HandlerMethodInvoker#initBinder
protected void initBinder(Object handler, String attrName, WebDataBinder binder, NativeWebRequest webRequest)
throws Exception {
if (this.bindingInitializer != null) {
this.bindingInitializer.initBinder(binder, webRequest);
}
if (handler != null) {
Set<Method> initBinderMethods = this.methodResolver.getInitBinderMethods();
if (!initBinderMethods.isEmpty()) {
boolean debug = logger.isDebugEnabled();
for (Method initBinderMethod : initBinderMethods) {
// 获取带有@InitBinder注解的方法
Method methodToInvoke = BridgeMethodResolver.findBridgedMethod(initBinderMethod);
String[] targetNames = AnnotationUtils.findAnnotation(initBinderMethod, InitBinder.class).value();
if (targetNames.length == 0 || Arrays.asList(targetNames).contains(attrName)) {
// 参数绑定 -》
Object[] initBinderArgs =
resolveInitBinderArguments(handler, methodToInvoke, binder, webRequest);
if (debug) {
logger.debug("Invoking init-binder method: " + methodToInvoke);
}
ReflectionUtils.makeAccessible(methodToInvoke);
// 执行方法-》
Object returnValue = methodToInvoke.invoke(handler, initBinderArgs);
if (returnValue != null) {
throw new IllegalStateException(
"InitBinder methods must not have a return value: " + methodToInvoke);
}
}
}
}
}
}返回方法org.springframework.web.bind.annotation.support.HandlerMethodInvoker#resolveRequestHeader
private Object resolveRequestHeader(String headerName, boolean required, String defaultValue,
MethodParameter methodParam, NativeWebRequest webRequest, Object handlerForInitBinderCall)
throws Exception {
Class<?> paramType = methodParam.getParameterType();
if (Map.class.isAssignableFrom(paramType)) {
return resolveRequestHeaderMap((Class<? extends Map<?, ?>>) paramType, webRequest);
}
if (headerName.length() == 0) {
headerName = getRequiredParameterName(methodParam);
}
Object headerValue = null;
String[] headerValues = webRequest.getHeaderValues(headerName);
if (headerValues != null) {
headerValue = (headerValues.length == 1 ? headerValues[0] : headerValues);
}
if (headerValue == null) {
if (defaultValue != null) {
headerValue = resolveDefaultValue(defaultValue);
}
else if (required) {
raiseMissingHeaderException(headerName, paramType);
}
headerValue = checkValue(headerName, headerValue, paramType);
}
WebDataBinder binder = createBinder(webRequest, null, headerName);
// 初始化绑定器-》
initBinder(handlerForInitBinderCall, headerName, binder, webRequest);
return binder.convertIfNecessary(headerValue, paramType, methodParam);
}返回方法org.springframework.web.bind.annotation.support.HandlerMethodInvoker#readWithMessageConverters
private Object readWithMessageConverters(MethodParameter methodParam, HttpInputMessage inputMessage, Class<?> paramType)
throws Exception {
MediaType contentType = inputMessage.getHeaders().getContentType();
if (contentType == null) {
StringBuilder builder = new StringBuilder(ClassUtils.getShortName(methodParam.getParameterType()));
String paramName = methodParam.getParameterName();
if (paramName != null) {
builder.append(' ');
builder.append(paramName);
}
throw new HttpMediaTypeNotSupportedException(
"Cannot extract parameter (" + builder.toString() + "): no Content-Type found");
}
List<MediaType> allSupportedMediaTypes = new ArrayList<MediaType>();
if (this.messageConverters != null) {
// 执行转换器
for (HttpMessageConverter<?> messageConverter : this.messageConverters) {
allSupportedMediaTypes.addAll(messageConverter.getSupportedMediaTypes());
if (messageConverter.canRead(paramType, contentType)) {
if (logger.isDebugEnabled()) {
logger.debug("Reading [" + paramType.getName() + "] as \"" + contentType
+"\" using [" + messageConverter + "]");
}
return messageConverter.read((Class) paramType, inputMessage);
}
}
}
throw new HttpMediaTypeNotSupportedException(contentType, allSupportedMediaTypes);
}返回方法org.springframework.web.bind.annotation.support.HandlerMethodInvoker#resolveCookieValue(java.lang.String, boolean, java.lang.String, org.springframework.core.MethodParameter, org.springframework.web.context.request.NativeWebRequest, java.lang.Object)
private Object resolveCookieValue(String cookieName, boolean required, String defaultValue,
MethodParameter methodParam, NativeWebRequest webRequest, Object handlerForInitBinderCall)
throws Exception {
Class<?> paramType = methodParam.getParameterType();
if (cookieName.length() == 0) {
cookieName = getRequiredParameterName(methodParam);
}
Object cookieValue = resolveCookieValue(cookieName, paramType, webRequest);
if (cookieValue == null) {
if (defaultValue != null) {
cookieValue = resolveDefaultValue(defaultValue);
}
else if (required) {
raiseMissingCookieException(cookieName, paramType);
}
cookieValue = checkValue(cookieName, cookieValue, paramType);
}
WebDataBinder binder = createBinder(webRequest, null, cookieName);
// 初始化绑定器-》
initBinder(handlerForInitBinderCall, cookieName, binder, webRequest);
return binder.convertIfNecessary(cookieValue, paramType, methodParam);
}返回方法org.springframework.web.bind.annotation.support.HandlerMethodInvoker#resolvePathVariable(java.lang.String, org.springframework.core.MethodParameter, org.springframework.web.context.request.NativeWebRequest, java.lang.Object)
private Object resolvePathVariable(String pathVarName, MethodParameter methodParam,
NativeWebRequest webRequest, Object handlerForInitBinderCall) throws Exception {
Class<?> paramType = methodParam.getParameterType();
if (pathVarName.length() == 0) {
pathVarName = getRequiredParameterName(methodParam);
}
String pathVarValue = resolvePathVariable(pathVarName, paramType, webRequest);
WebDataBinder binder = createBinder(webRequest, null, pathVarName);
// 初始化绑定器-》
initBinder(handlerForInitBinderCall, pathVarName, binder, webRequest);
return binder.convertIfNecessary(pathVarValue, paramType, methodParam);
}返回方法org.springframework.web.bind.annotation.support.HandlerMethodInvoker#resolveModelAttribute
private WebDataBinder resolveModelAttribute(String attrName, MethodParameter methodParam,
ExtendedModelMap implicitModel, NativeWebRequest webRequest, Object handler) throws Exception {
// Bind request parameter onto object...
String name = attrName;
if ("".equals(name)) {
name = Conventions.getVariableNameForParameter(methodParam);
}
Class<?> paramType = methodParam.getParameterType();
Object bindObject;
if (implicitModel.containsKey(name)) {
bindObject = implicitModel.get(name);
}
else if (this.methodResolver.isSessionAttribute(name, paramType)) {
bindObject = this.sessionAttributeStore.retrieveAttribute(webRequest, name);
if (bindObject == null) {
raiseSessionRequiredException("Session attribute '" + name + "' required - not found in session");
}
}
else {
bindObject = BeanUtils.instantiateClass(paramType);
}
WebDataBinder binder = createBinder(webRequest, bindObject, name);
// 初始化绑定器-》
initBinder(handler, name, binder, webRequest);
return binder;
}返回方法org.springframework.web.bind.annotation.support.HandlerMethodInvoker#doBind(org.springframework.web.bind.WebDataBinder, org.springframework.web.context.request.NativeWebRequest, boolean, java.lang.Object[], boolean)
private void doBind(WebDataBinder binder, NativeWebRequest webRequest, boolean validate,
Object[] validationHints, boolean failOnErrors) throws Exception {
doBind(binder, webRequest);
if (validate) {
// 执行参数验证
binder.validate(validationHints);
}
if (failOnErrors && binder.getBindingResult().hasErrors()) {
throw new BindException(binder.getBindingResult());
}
}返回方法org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.ServletHandlerMethodInvoker#getModelAndView
public ModelAndView getModelAndView(Method handlerMethod, Class<?> handlerType, Object returnValue,
ExtendedModelMap implicitModel, ServletWebRequest webRequest) throws Exception {
// 解析@ResponseStatus注解
ResponseStatus responseStatus = AnnotatedElementUtils.findMergedAnnotation(handlerMethod, ResponseStatus.class);
if (responseStatus != null) {
HttpStatus statusCode = responseStatus.code();
String reason = responseStatus.reason();
if (!StringUtils.hasText(reason)) {
webRequest.getResponse().setStatus(statusCode.value());
}
else {
webRequest.getResponse().sendError(statusCode.value(), reason);
}
// to be picked up by the RedirectView
webRequest.getRequest().setAttribute(View.RESPONSE_STATUS_ATTRIBUTE, statusCode);
this.responseArgumentUsed = true;
}
// Invoke custom resolvers if present...
if (customModelAndViewResolvers != null) {
for (ModelAndViewResolver mavResolver : customModelAndViewResolvers) {
// 解析modelAndView-》
ModelAndView mav = mavResolver.resolveModelAndView(
handlerMethod, handlerType, returnValue, implicitModel, webRequest);
if (mav != ModelAndViewResolver.UNRESOLVED) {
return mav;
}
}
}
if (returnValue instanceof HttpEntity) {
// 解析HttpEntity响应
handleHttpEntityResponse((HttpEntity<?>) returnValue, webRequest);
return null;
}
// 解析@ResponseBody注解
else if (AnnotationUtils.findAnnotation(handlerMethod, ResponseBody.class) != null) {
// -》
handleResponseBody(returnValue, webRequest);
return null;
}
else if (returnValue instanceof ModelAndView) {
// 如果返回值是modelAndView创建并返回
ModelAndView mav = (ModelAndView) returnValue;
mav.getModelMap().mergeAttributes(implicitModel);
return mav;
}
else if (returnValue instanceof Model) {
// 返回值是model
return new ModelAndView().addAllObjects(implicitModel).addAllObjects(((Model) returnValue).asMap());
}
else if (returnValue instanceof View) {
// 返回值是view
return new ModelAndView((View) returnValue).addAllObjects(implicitModel);
}
// 解析@ModelAttribute注解
else if (AnnotationUtils.findAnnotation(handlerMethod, ModelAttribute.class) != null) {
// -》
addReturnValueAsModelAttribute(handlerMethod, handlerType, returnValue, implicitModel);
return new ModelAndView().addAllObjects(implicitModel);
}
else if (returnValue instanceof Map) {
// 返回值是map
return new ModelAndView().addAllObjects(implicitModel).addAllObjects((Map<String, ?>) returnValue);
}
else if (returnValue instanceof String) {
// 返回值是string
return new ModelAndView((String) returnValue).addAllObjects(implicitModel);
}
else if (returnValue == null) {
// 没有返回值
// Either returned null or was 'void' return.
if (this.responseArgumentUsed || webRequest.isNotModified()) {
return null;
}
else {
// Assuming view name translation...
return new ModelAndView().addAllObjects(implicitModel);
}
}
else if (!BeanUtils.isSimpleProperty(returnValue.getClass())) {
// Assume a single model attribute...
addReturnValueAsModelAttribute(handlerMethod, handlerType, returnValue, implicitModel);
return new ModelAndView().addAllObjects(implicitModel);
}
else {
throw new IllegalArgumentException("Invalid handler method return value: " + returnValue);
}
}进入方法org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.ServletHandlerMethodInvoker#handleHttpEntityResponse
private void handleHttpEntityResponse(HttpEntity<?> responseEntity, ServletWebRequest webRequest) throws Exception {
if (responseEntity == null) {
return;
}
HttpInputMessage inputMessage = createHttpInputMessage(webRequest);
HttpOutputMessage outputMessage = createHttpOutputMessage(webRequest);
if (responseEntity instanceof ResponseEntity && outputMessage instanceof ServerHttpResponse) {
((ServerHttpResponse) outputMessage).setStatusCode(((ResponseEntity<?>) responseEntity).getStatusCode());
}
HttpHeaders entityHeaders = responseEntity.getHeaders();
if (!entityHeaders.isEmpty()) {
outputMessage.getHeaders().putAll(entityHeaders);
}
Object body = responseEntity.getBody();
if (body != null) {
// 调用转换器-》
writeWithMessageConverters(body, inputMessage, outputMessage);
}
else {
// flush headers
outputMessage.getBody();
}
}返回方法org.springframework.web.servlet.DispatcherServlet#applyDefaultViewName
private void applyDefaultViewName(HttpServletRequest request, ModelAndView mv) throws Exception {
if (mv != null && !mv.hasView()) {
mv.setViewName(getDefaultViewName(request));
}
}进入方法org.springframework.web.servlet.DispatcherServlet#getDefaultViewName
protected String getDefaultViewName(HttpServletRequest request) throws Exception {
return this.viewNameTranslator.getViewName(request);
}返回方法org.springframework.web.servlet.HandlerExecutionChain#applyPostHandle
void applyPostHandle(HttpServletRequest request, HttpServletResponse response, ModelAndView mv) throws Exception {
HandlerInterceptor[] interceptors = getInterceptors();
if (!ObjectUtils.isEmpty(interceptors)) {
for (int i = interceptors.length - 1; i >= 0; i--) {
HandlerInterceptor interceptor = interceptors[i];
// 执行业务handler拦截器后置方法
interceptor.postHandle(request, response, this.handler, mv);
}
}
}进入方法org.springframework.web.servlet.HandlerExecutionChain#getInterceptors
public HandlerInterceptor[] getInterceptors() {
if (this.interceptors == null && this.interceptorList != null) {
this.interceptors = this.interceptorList.toArray(new HandlerInterceptor[this.interceptorList.size()]);
}
return this.interceptors;
}进入方法org.springframework.web.servlet.DispatcherServlet#processDispatchResult
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);
// 用异常解析器处理异常-》
mv = processHandlerException(request, response, handler, exception);
errorView = (mv != null);
}
}
// Did the handler return a view to render?
if (mv != null && !mv.wasCleared()) {
render(mv, request, response);
if (errorView) {
// 清空绑定 -》
WebUtils.clearErrorRequestAttributes(request);
}
}
else {
if (logger.isDebugEnabled()) {
logger.debug("Null ModelAndView returned to DispatcherServlet with name '" + getServletName() +
"': assuming HandlerAdapter completed request handling");
}
}
// 异步请求，同步直接返回
if (WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) {
// Concurrent handling started during a forward
return;
}
if (mappedHandler != null) {
// 执行拦截器的处理完成事件 -》
mappedHandler.triggerAfterCompletion(request, response, null);
}
}进入方法org.springframework.web.servlet.DispatcherServlet#processHandlerException
protected ModelAndView processHandlerException(HttpServletRequest request, HttpServletResponse response,
Object handler, Exception ex) throws Exception {
// Check registered HandlerExceptionResolvers...
ModelAndView exMv = null;
for (HandlerExceptionResolver handlerExceptionResolver : this.handlerExceptionResolvers) {
exMv = handlerExceptionResolver.resolveException(request, response, handler, ex);
if (exMv != null) {
break;
}
}
if (exMv != null) {
if (exMv.isEmpty()) {
request.setAttribute(EXCEPTION_ATTRIBUTE, ex);
return null;
}
// We might still need view name translation for a plain error model...
if (!exMv.hasView()) {
// 设置默认视图
exMv.setViewName(getDefaultViewName(request));
}
if (logger.isDebugEnabled()) {
logger.debug("Handler execution resulted in exception - forwarding to resolved error view: " + exMv, ex);
}
// 绑定配置-》
WebUtils.exposeErrorRequestAttributes(request, ex, getServletName());
return exMv;
}
throw ex;
}进入方法org.springframework.web.util.WebUtils#exposeErrorRequestAttributes
public static void exposeErrorRequestAttributes(HttpServletRequest request, Throwable ex, String servletName) {
exposeRequestAttributeIfNotPresent(request, ERROR_STATUS_CODE_ATTRIBUTE, HttpServletResponse.SC_OK);
exposeRequestAttributeIfNotPresent(request, ERROR_EXCEPTION_TYPE_ATTRIBUTE, ex.getClass());
exposeRequestAttributeIfNotPresent(request, ERROR_MESSAGE_ATTRIBUTE, ex.getMessage());
exposeRequestAttributeIfNotPresent(request, ERROR_EXCEPTION_ATTRIBUTE, ex);
exposeRequestAttributeIfNotPresent(request, ERROR_REQUEST_URI_ATTRIBUTE, request.getRequestURI());
exposeRequestAttributeIfNotPresent(request, ERROR_SERVLET_NAME_ATTRIBUTE, servletName);
}返回方法org.springframework.web.util.WebUtils#clearErrorRequestAttributes
public static void clearErrorRequestAttributes(HttpServletRequest request) {
request.removeAttribute(ERROR_STATUS_CODE_ATTRIBUTE);
request.removeAttribute(ERROR_EXCEPTION_TYPE_ATTRIBUTE);
request.removeAttribute(ERROR_MESSAGE_ATTRIBUTE);
request.removeAttribute(ERROR_EXCEPTION_ATTRIBUTE);
request.removeAttribute(ERROR_REQUEST_URI_ATTRIBUTE);
request.removeAttribute(ERROR_SERVLET_NAME_ATTRIBUTE);
}返回方法org.springframework.web.servlet.HandlerExecutionChain#triggerAfterCompletion
void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response, Exception ex)
throws Exception {
// 获取拦截器 -》
HandlerInterceptor[] interceptors = getInterceptors();
if (!ObjectUtils.isEmpty(interceptors)) {
for (int i = this.interceptorIndex; i >= 0; i--) {
HandlerInterceptor interceptor = interceptors[i];
try {
// 执行拦截器的完成事件
interceptor.afterCompletion(request, response, this.handler, ex);
}
catch (Throwable ex2) {
logger.error("HandlerInterceptor.afterCompletion threw exception", ex2);
}
}
}
}进入方法org.springframework.web.servlet.HandlerExecutionChain#getInterceptors
public HandlerInterceptor[] getInterceptors() {
if (this.interceptors == null && this.interceptorList != null) {
this.interceptors = this.interceptorList.toArray(new HandlerInterceptor[this.interceptorList.size()]);
}
return this.interceptors;
}返回方法org.springframework.web.servlet.DispatcherServlet#triggerAfterCompletion
private void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response,
HandlerExecutionChain mappedHandler, Exception ex) throws Exception {
if (mappedHandler != null) {
mappedHandler.triggerAfterCompletion(request, response, ex);
}
throw ex;
}进入方法org.springframework.web.servlet.HandlerExecutionChain#triggerAfterCompletion
void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response, Exception ex)
throws Exception {
// 获取拦截器 -》
HandlerInterceptor[] interceptors = getInterceptors();
if (!ObjectUtils.isEmpty(interceptors)) {
for (int i = this.interceptorIndex; i >= 0; i--) {
HandlerInterceptor interceptor = interceptors[i];
try {
// 执行拦截器的完成事件
interceptor.afterCompletion(request, response, this.handler, ex);
}
catch (Throwable ex2) {
logger.error("HandlerInterceptor.afterCompletion threw exception", ex2);
}
}
}
}返回方法org.springframework.web.servlet.HandlerExecutionChain#applyAfterConcurrentHandlingStarted
void applyAfterConcurrentHandlingStarted(HttpServletRequest request, HttpServletResponse response) {
HandlerInterceptor[] interceptors = getInterceptors();
if (!ObjectUtils.isEmpty(interceptors)) {
for (int i = interceptors.length - 1; i >= 0; i--) {
if (interceptors[i] instanceof AsyncHandlerInterceptor) {
try {
AsyncHandlerInterceptor asyncInterceptor = (AsyncHandlerInterceptor) interceptors[i];
asyncInterceptor.afterConcurrentHandlingStarted(request, response, this.handler);
}
catch (Throwable ex) {
logger.error("Interceptor [" + interceptors[i] + "] failed in afterConcurrentHandlingStarted", ex);
}
}
}
}
}返回方法org.springframework.web.servlet.DispatcherServlet#restoreAttributesAfterInclude
private void restoreAttributesAfterInclude(HttpServletRequest request, Map<?,?> attributesSnapshot) {
// Need to copy into separate Collection here, to avoid side effects
// on the Enumeration when removing attributes.
Set<String> attrsToCheck = new HashSet<String>();
Enumeration<?> attrNames = request.getAttributeNames();
while (attrNames.hasMoreElements()) {
String attrName = (String) attrNames.nextElement();
if (this.cleanupAfterInclude || attrName.startsWith(DEFAULT_STRATEGIES_PREFIX)) {
attrsToCheck.add(attrName);
}
}
// Add attributes that may have been removed
attrsToCheck.addAll((Set<String>) attributesSnapshot.keySet());
// Iterate over the attributes to check, restoring the original value
// or removing the attribute, respectively, if appropriate.
for (String attrName : attrsToCheck) {
Object attrValue = attributesSnapshot.get(attrName);
if (attrValue == null){
request.removeAttribute(attrName);
}
else if (attrValue != request.getAttribute(attrName)) {
request.setAttribute(attrName, attrValue);
}
}
}往上返回到这个方法org.springframework.web.servlet.FrameworkServlet#service
说到最后
本次源码解析仅代表个人观点，仅供参考。