服务方法 请求的第一个方法
/**
* Exposes the DispatcherServlet-specific request attributes and delegates to {@link #doDispatch}
* for the actual dispatching.
*/
@Override
protected void doService(HttpServletRequest request, HttpServletResponse response) throws Exception {
if (logger.isDebugEnabled()) {
String requestUri = urlPathHelper.getRequestUri(request);
logger.debug("DispatcherServlet with name '" + getServletName() + "' processing " + request.getMethod() +
" request for [" + requestUri + "]");
}
// Keep a snapshot of the request attributes in case of an include,
// to be able to restore the original attributes after the include.
Map<String, Object> attributesSnapshot = null;
if (WebUtils.isIncludeRequest(request)) {
logger.debug("Taking snapshot of request attributes before include");
attributesSnapshot = new HashMap<String, Object>();
Enumeration attrNames = request.getAttributeNames();
while (attrNames.hasMoreElements()) {
String attrName = (String) attrNames.nextElement();
if (this.cleanupAfterInclude || attrName.startsWith("org.springframework.web.servlet")) {
attributesSnapshot.put(attrName, request.getAttribute(attrName));
}
}
}
// Make framework objects available to handlers and view objects.
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());
try {
[u][b]doDispatch(request, response);[/b][/u] }
finally {
// Restore the original attribute snapshot, in case of an include.
if (attributesSnapshot != null) {
restoreAttributesAfterInclude(request, attributesSnapshot);
}
}
}
Process the actual dispatching to the handler
本次请求实际的请求方法
/**
* Process the actual dispatching to the handler.
* <p>The handler will be obtained by applying the servlet's HandlerMappings in order.
* The HandlerAdapter will be obtained by querying the servlet's installed HandlerAdapters
* to find the first that supports the handler class.
* <p>All HTTP methods are handled by this method. It's up to HandlerAdapters or handlers
* themselves to decide which methods are acceptable.
* @param request current HTTP request
* @param response current HTTP response
* @throws Exception in case of any kind of processing failure
*/
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
HttpServletRequest processedRequest = request;
HandlerExecutionChain mappedHandler = null;
int interceptorIndex = -1;
try {
ModelAndView mv;
boolean errorView = false;
try {
processedRequest = checkMultipart(request);
// Determine handler for the current request.
mappedHandler = getHandler(processedRequest, false);
if (mappedHandler == null || mappedHandler.getHandler() == null) {
noHandlerFound(processedRequest, response);
return;
}
// Determine handler adapter for the current request.
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()) {
String requestUri = urlPathHelper.getRequestUri(request);
logger.debug("Last-Modified value for [" + requestUri + "] is: " + lastModified);
}
//如果是get请求则判断是否有客户端缓存
if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) {
return;
}
}
// Apply preHandle methods of registered interceptors.
HandlerInterceptor[] interceptors = mappedHandler.getInterceptors();
if (interceptors != null) {
for (int i = 0; i < interceptors.length; i++) {
HandlerInterceptor interceptor = interceptors[i];
if (!interceptor.preHandle(processedRequest, response, mappedHandler.getHandler())) {
triggerAfterCompletion(mappedHandler, interceptorIndex, processedRequest, response, null);
return;
}
interceptorIndex = i;
}
}
//实际请求方法
// Actually invoke the handler.
mv =[b] ha.handle(processedRequest, response, mappedHandler.getHandler());[/b]
// Do we need view name translation?
if (mv != null && !mv.hasView()) {
mv.setViewName(getDefaultViewName(request));
}
// Apply postHandle methods of registered interceptors.
if (interceptors != null) {
for (int i = interceptors.length - 1; i >= 0; i--) {
HandlerInterceptor interceptor = interceptors[i];
interceptor.postHandle(processedRequest, response, mappedHandler.getHandler(), mv);
}
}
}
catch (ModelAndViewDefiningException ex) {
logger.debug("ModelAndViewDefiningException encountered", ex);
mv = ex.getModelAndView();
}
catch (Exception ex) {
Object handler = (mappedHandler != null ? mappedHandler.getHandler() : null);
mv = processHandlerException(processedRequest, response, handler, ex);
errorView = (mv != null);
}
// Did the handler return a view to render?
if (mv != null && !mv.wasCleared()) {
render(mv, processedRequest, 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");
}
}
// Trigger after-completion for successful outcome.
triggerAfterCompletion(mappedHandler, interceptorIndex, processedRequest, response, null);
}
catch (Exception ex) {
// Trigger after-completion for thrown exception.
triggerAfterCompletion(mappedHandler, interceptorIndex, processedRequest, response, ex);
throw ex;
}
catch (Error err) {
ServletException ex = new NestedServletException("Handler processing failed", err);
// Trigger after-completion for thrown exception.
triggerAfterCompletion(mappedHandler, interceptorIndex, processedRequest, response, ex);
throw ex;
}
finally {
// Clean up any resources used by a multipart request.
if (processedRequest != request) {
cleanupMultipart(processedRequest);
}
}
}
4个实现类
//AnnotationMethodHandlerAdapter 注解实现类
public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
Class<?> clazz = ClassUtils.getUserClass(handler);
Boolean annotatedWithSessionAttributes = this.sessionAnnotatedClassesCache.get(clazz);
if (annotatedWithSessionAttributes == null) {
annotatedWithSessionAttributes = (AnnotationUtils.findAnnotation(clazz, SessionAttributes.class) != null);
this.sessionAnnotatedClassesCache.put(clazz, annotatedWithSessionAttributes);
}
if (annotatedWithSessionAttributes) {
// Always prevent caching in case of session attribute management.
checkAndPrepare(request, response, this.cacheSecondsForSessionAttributeHandlers, true);
// Prepare cached set of session attributes names.
}
else {
// Uses configured default cacheSeconds setting.
checkAndPrepare(request, response, true);
}
// Execute invokeHandlerMethod in synchronized block if required.
if (this.synchronizeOnSession) {
HttpSession session = request.getSession(false);
if (session != null) {
Object mutex = WebUtils.getSessionMutex(session);
synchronized (mutex) {
return invokeHandlerMethod(request, response, handler);
}
}
}
[b]return invokeHandlerMethod(request, response, handler);[/b] }
protected ModelAndView invokeHandlerMethod(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
//handler方法解析器
ServletHandlerMethodResolver methodResolver = getMethodResolver(handler);
//handler方法
Method handlerMethod = methodResolver.resolveHandlerMethod(request);
//handler方法的执行器
ServletHandlerMethodInvoker methodInvoker = new ServletHandlerMethodInvoker(methodResolver);
ServletWebRequest webRequest = new ServletWebRequest(request, response);
//上下文map对象 request 及session中的Attribute
ExtendedModelMap implicitModel = new BindingAwareModelMap();
//执行handler方法
Object [b]result [/b]= methodInvoker.invokeHandlerMethod(handlerMethod, handler, webRequest, implicitModel);
//将执行结果转化的为modelAndView对象
ModelAndView mav =
methodInvoker.getModelAndView(handlerMethod, handler.getClass(), [b]result[/b], implicitModel, webRequest);
//将当前上下文的内容更新到modelView对象中
methodInvoker.updateModelAttributes(handler, (mav != null ? mav.getModel() : null), implicitModel, webRequest);
return mav;
}
执行handler 方法
public final Object invokeHandlerMethod(Method handlerMethod, Object handler,
NativeWebRequest webRequest, ExtendedModelMap implicitModel) throws Exception {
Method handlerMethodToInvoke = BridgeMethodResolver.findBridgedMethod(handlerMethod);
try {
boolean debug = logger.isDebugEnabled();
//将ssesion中的内容加入到 implicitModel
for (String attrName : this.methodResolver.getActualSessionAttributeNames()) {
Object attrValue = this.sessionAttributeStore.retrieveAttribute(webRequest, attrName);
if (attrValue != null) {
implicitModel.addAttribute(attrName, attrValue);
}
}
/*先执行ModelAttributeMethods暴露表单引用对象为模型数据：放在处理器的一般方法（非功能处理方法）上时，是为表单准备要展示的表单引用对象，如注册时需要选择的所在城市等，而且在执行功能处理方法（@RequestMapping注解的方法）之前，自动添加到模型对象中，用于视图页面展示时使用
/**
* Annotation that binds a method parameter or method return value
* to a named model attribute, exposed to a web view. Supported
* for {@link RequestMapping} annotated handler classes.
*
* <p>Can be used to expose command objects to a web view, using
* specific attribute names, through annotating corresponding
* parameters of a {@link RequestMapping} annotated handler method).
*
* <p>Can also be used to expose reference data to a web view
* through annotating accessor methods in a controller class which
* is based on {@link RequestMapping} annotated handler methods,
* with such accessor methods allowed to have any arguments that
* {@link RequestMapping} supports for handler methods, returning
* the model attribute value to expose.
*
* @author Juergen Hoeller
* @since 2.5
*/
@Target({ElementType.PARAMETER, ElementType.METHOD})
//该注解可以注解在方法或参数上
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ModelAttribute {
/**
* The name of the model attribute to bind to.
* <p>The default model attribute name is inferred from the declared
* attribute type (i.e. the method parameter type or method return type),
* based on the non-qualified class name:
* e.g. "orderAddress" for class "mypackage.OrderAddress",
* or "orderAddressList" for "List<mypackage.OrderAddress>".
*/
String value() default "";
}
*/
//该注解在方法上
for (Method attributeMethod : this.methodResolver.getModelAttributeMethods()) {
Method attributeMethodToInvoke = BridgeMethodResolver.findBridgedMethod(attributeMethod);
Object[] args = [b]resolveHandlerArguments(attributeMethodToInvoke, handler, webRequest, implicitModel);[/b] if (debug) {
logger.debug("Invoking model attribute method: " + attributeMethodToInvoke);
}
String attrName = AnnotationUtils.findAnnotation(attributeMethod, ModelAttribute.class).value();
if (!"".equals(attrName) && implicitModel.containsAttribute(attrName)) {
continue;
}
ReflectionUtils.makeAccessible(attributeMethodToInvoke);
Object attrValue = attributeMethodToInvoke.invoke(handler, args);
if ("".equals(attrName)) {
Class resolvedType = GenericTypeResolver.resolveReturnType(attributeMethodToInvoke, handler.getClass());
attrName = Conventions.getVariableNameForReturnType(attributeMethodToInvoke, resolvedType, attrValue);
}
if (!implicitModel.containsAttribute(attrName)) {
implicitModel.addAttribute(attrName, attrValue);
}
}
Object[] args = resolveHandlerArguments(handlerMethodToInvoke, handler, webRequest, implicitModel);
if (debug) {
logger.debug("Invoking request handler method: " + handlerMethodToInvoke);
}
ReflectionUtils.makeAccessible(handlerMethodToInvoke);
//执行请求方法
return handlerMethodToInvoke.invoke(handler, args);
}
catch (IllegalStateException ex) {
// Internal assertion failed (e.g. invalid signature):
// throw exception with full handler method context...
throw new HandlerMethodInvocationException(handlerMethodToInvoke, ex);
}
catch (InvocationTargetException ex) {
// User-defined @ModelAttribute/@InitBinder/@RequestMapping method threw an exception...
ReflectionUtils.rethrowException(ex.getTargetException());
return null;
}
}
获取反射执行方法所需要的参数
private Object[] resolveHandlerArguments(Method handlerMethod, Object handler,
NativeWebRequest webRequest, ExtendedModelMap implicitModel) throws Exception {
Class[] paramTypes = handlerMethod.getParameterTypes();
Object[] args = new Object[paramTypes.length];
for (int i = 0; i < args.length; i++) {
MethodParameter methodParam = new MethodParameter(handlerMethod, i);
methodParam.initParameterNameDiscovery(this.parameterNameDiscoverer);
GenericTypeResolver.resolveParameterType(methodParam, handler.getClass());
String paramName = null;
String headerName = null;
boolean requestBodyFound = false;
String cookieName = null;
String pathVarName = null;
String attrName = null;
boolean required = false;
String defaultValue = null;
boolean validate = false;
int annotationsFound = 0;
Annotation[] paramAnns = methodParam.getParameterAnnotations();
for (Annotation paramAnn : paramAnns) {
if (RequestParam.class.isInstance(paramAnn)) {
RequestParam requestParam = (RequestParam) paramAnn;
paramName = requestParam.value();
required = requestParam.required();
defaultValue = parseDefaultValueAttribute(requestParam.defaultValue());
annotationsFound++;
}
else if (RequestHeader.class.isInstance(paramAnn)) {
RequestHeader requestHeader = (RequestHeader) paramAnn;
headerName = requestHeader.value();
required = requestHeader.required();
defaultValue = parseDefaultValueAttribute(requestHeader.defaultValue());
annotationsFound++;
}
else if (RequestBody.class.isInstance(paramAnn)) {
requestBodyFound = true;
annotationsFound++;
}
else if (CookieValue.class.isInstance(paramAnn)) {
CookieValue cookieValue = (CookieValue) paramAnn;
cookieName = cookieValue.value();
required = cookieValue.required();
defaultValue = parseDefaultValueAttribute(cookieValue.defaultValue());
annotationsFound++;
}
else if (PathVariable.class.isInstance(paramAnn)) {
PathVariable pathVar = (PathVariable) paramAnn;
pathVarName = pathVar.value();
annotationsFound++;
}
//这里是参数类型 该注解在参数上
else if (ModelAttribute.class.isInstance(paramAnn)) {
ModelAttribute attr = (ModelAttribute) paramAnn;
attrName = attr.value();
annotationsFound++;
}
else if (Value.class.isInstance(paramAnn)) {
defaultValue = ((Value) paramAnn).value();
}
else if ("Valid".equals(paramAnn.annotationType().getSimpleName())) {
validate = true;
}
}
if (annotationsFound > 1) {
throw new IllegalStateException("Handler parameter annotations are exclusive choices - " +
"do not specify more than one such annotation on the same parameter: " + handlerMethod);
}
if (annotationsFound == 0) {
Object argValue = resolveCommonArgument(methodParam, webRequest);
if (argValue != WebArgumentResolver.UNRESOLVED) {
args[i] = argValue;
}
else if (defaultValue != null) {
args[i] = resolveDefaultValue(defaultValue);
}
else {
Class paramType = methodParam.getParameterType();
if (Model.class.isAssignableFrom(paramType) || Map.class.isAssignableFrom(paramType)) {
args[i] = implicitModel;
}
else if (SessionStatus.class.isAssignableFrom(paramType)) {
args[i] = this.sessionStatus;
}
else if (HttpEntity.class.isAssignableFrom(paramType)) {
args[i] = resolveHttpEntityRequest(methodParam, webRequest);
}
else if (Errors.class.isAssignableFrom(paramType)) {
throw new IllegalStateException("Errors/BindingResult argument declared " +
"without preceding model attribute. Check your handler method signature!");
}
else if (BeanUtils.isSimpleProperty(paramType)) {
paramName = "";
}
else {
attrName = "";
}
}
}
if (paramName != null) {
args[i] = resolveRequestParam(paramName, required, defaultValue, methodParam, webRequest, handler);
}
else if (headerName != null) {
args[i] = resolveRequestHeader(headerName, required, defaultValue, methodParam, webRequest, handler);
}
else if (requestBodyFound) {
args[i] = resolveRequestBody(methodParam, webRequest, handler);
}
else if (cookieName != null) {
args[i] = resolveCookieValue(cookieName, required, defaultValue, methodParam, webRequest, handler);
}
else if (pathVarName != null) {
args[i] = resolvePathVariable(pathVarName, methodParam, webRequest, handler);
}
//struts 2的模型驱动
else if (attrName != null) {
WebDataBinder binder =
resolveModelAttribute(attrName, methodParam, implicitModel, webRequest, handler);
boolean assignBindingResult = (args.length > i + 1 && Errors.class.isAssignableFrom(paramTypes[i + 1]));
if (binder.getTarget() != null) {
doBind(binder, webRequest, validate, !assignBindingResult);
}
args[i] = binder.getTarget();
if (assignBindingResult) {
args[i + 1] = binder.getBindingResult();
i++;
}
implicitModel.putAll(binder.getBindingResult().getModel());
}
}
return args;
}
//模型注入
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);
initBinder(handler, name, binder, webRequest);
return binder;
}
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) {
Method methodToInvoke = BridgeMethodResolver.findBridgedMethod(initBinderMethod);
String[] targetNames = AnnotationUtils.findAnnotation(initBinderMethod, InitBinder.class).value();
if (targetNames.length == 0 || Arrays.asList(targetNames).contains(attrName)) {
Object[] initBinderArgs =
resolveInitBinderArguments(handler, methodToInvoke, binder, webRequest);
if (debug) {
logger.debug("Invoking init-binder method: " + methodToInvoke);
}
ReflectionUtils.makeAccessible(methodToInvoke);
Object returnValue = methodToInvoke.invoke(handler, initBinderArgs);
if (returnValue != null) {
throw new IllegalStateException(
"InitBinder methods must not have a return value: " + methodToInvoke);
}
}
}
}
}
}