【转】SpringMVC源码分析和一些常用最佳实践

@RequestMapping(value = "/getTemplateInfo", method = RequestMethod.GET)
@ResponseBody
public JsonObject<?> getTemplateInfo(@RequestParam(value = "userId", required = true) int userId, @RequestParam(value = "groupType") int groupType) {

// ... logic here

}

<servlet>
<servlet-name>spring</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>  </servlet>
<servlet-mapping>
<servlet-name>spring</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>

public static final String HANDLER_ADAPTER_BEAN_NAME = "handlerAdapter";

private List handlerAdapters;

public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler,
Exception ex) {
if (shouldApplyTo(request, handler)) {
logException(ex, request);
prepareResponse(ex, response);
return doResolveException(request, response, handler, ex);
} else {
return null;
}
}

protected abstract ModelAndView doResolveException(HttpServletRequest request, HttpServletResponse response,
Object handler, Exception ex);

// 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;
}
}

public interface HandlerInterceptor {
boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception;
}

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()
+ "'");
}
HandlerExecutionChain handler = hm.getHandler(request);
if (handler != null) {
return handler;
}
}
return null;
}

// 在Spring容器中初始化
public void afterPropertiesSet() {
initHandlerMethods();
}

// 初始化HandlerMethod
protected void initHandlerMethods() {
String[] beanNames = (this.detectHandlerMethodsInAncestorContexts ? BeanFactoryUtils
.beanNamesForTypeIncludingAncestors(getApplicationContext(), Object.class) : getApplicationContext()
.getBeanNamesForType(Object.class));

for (String beanName : beanNames) {
if (isHandler(getApplicationContext().getType(beanName))) {
detectHandlerMethods(beanName);
}
}
handlerMethodsInitialized(getHandlerMethods());
}

// 看某个bean是否是controller
protected boolean isHandler(Class<?> beanType) {
return ((AnnotationUtils.findAnnotation(beanType, Controller.class) != null) || (AnnotationUtils
.findAnnotation(beanType, RequestMapping.class) != null));
}

// 获取某个controller下所有的Method，做url path->Method的简单关联
protected void detectHandlerMethods(final Object handler) {
Class<?> handlerType = (handler instanceof String) ? getApplicationContext().getType((String) handler)
: handler.getClass();

final Class<?> userType = ClassUtils.getUserClass(handlerType);

Set methods = HandlerMethodSelector.selectMethods(userType, new MethodFilter() {
public boolean matches(Method method) {
return getMappingForMethod(method, userType) != null;
}
});

for (Method method : methods) {
T mapping = getMappingForMethod(method, userType);
registerHandlerMethod(handler, method, mapping);
}
}

[/portal/ad/getTemplateInfo],methods=[GET],params=[],headers=[],consumes=[],produces=[],custom=[]}=public com.baidu.beidou.ui.web.common.vo.JsonObject<?>com.baidu.beidou.ui.web.portal.ad.controller.SiConfController.getTemplateInfo(int,int)]

private final Map<T, HandlerMethod> handlerMethods = new LinkedHashMap<T, HandlerMethod>();

public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
Object handler = getHandlerInternal(request);
if (handler == null) {
handler = getDefaultHandler();
}
if (handler == null) {
return null;
}
// Bean name or resolved handler?
if (handler instanceof String) {
String handlerName = (String) handler;
handler = getApplicationContext().getBean(handlerName);
}
return getHandlerExecutionChain(handler, request);
}

protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) {
HandlerExecutionChain chain = (handler instanceof HandlerExecutionChain) ? (HandlerExecutionChain) handler
: new HandlerExecutionChain(handler);

chain.addInterceptors(getAdaptedInterceptors());

String lookupPath = urlPathHelper.getLookupPathForRequest(request);
for (MappedInterceptor mappedInterceptor : mappedInterceptors) {
if (mappedInterceptor.matches(lookupPath, pathMatcher)) {
chain.addInterceptor(mappedInterceptor.getInterceptor());
}
}

return chain;
}

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");
}

public interface HandlerAdapter {
ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception;
}

// 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;
}
}

private ModelAndView invokeHandlerMethod(HttpServletRequest request, HttpServletResponse response,
HandlerMethod handlerMethod) throws Exception {

ServletWebRequest webRequest = new ServletWebRequest(request, response);

WebDataBinderFactory binderFactory = getDataBinderFactory(handlerMethod);
ModelFactory modelFactory = getModelFactory(handlerMethod, binderFactory);
ServletInvocableHandlerMethod requestMappingMethod = createRequestMappingMethod(handlerMethod, binderFactory);

ModelAndViewContainer mavContainer = new ModelAndViewContainer();
mavContainer.addAllAttributes(RequestContextUtils.getInputFlashMap(request));
modelFactory.initModel(webRequest, mavContainer, requestMappingMethod);
mavContainer.setIgnoreDefaultModelOnRedirect(this.ignoreDefaultModelOnRedirect);

requestMappingMethod.invokeAndHandle(webRequest, mavContainer);
// ... return ModelAndView
}

public final Object invokeForRequest(NativeWebRequest request, ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
Object[] args = getMethodArgumentValues(request, mavContainer, providedArgs);
Object returnValue = invoke(args);
return returnValue;
}

private Object[] getMethodArgumentValues(NativeWebRequest request, ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {

MethodParameter[] parameters = getMethodParameters();
Object[] args = new Object[parameters.length];
for (int i = 0; i < parameters.length; i++) {
MethodParameter parameter = parameters[i];
parameter.initParameterNameDiscovery(parameterNameDiscoverer);
GenericTypeResolver.resolveParameterType(parameter, getBean().getClass());

args[i] = resolveProvidedArgument(parameter, providedArgs);
if (args[i] != null) {
continue;
}

if (argumentResolvers.supportsParameter(parameter)) {
try {
args[i] = argumentResolvers.resolveArgument(parameter, mavContainer, request, dataBinderFactory);
continue;
} catch (Exception ex) {
if (logger.isTraceEnabled()) {
logger.trace(getArgumentResolutionErrorMessage("Error resolving argument", i), ex);
}
throw ex;
}
}

if (args[i] == null) {
String msg = getArgumentResolutionErrorMessage("No suitable resolver for argument", i);
throw new IllegalStateException(msg);
}
}
return args;
}

void applyPostHandle(HttpServletRequest request, HttpServletResponse response, ModelAndView mv) throws Exception {
if (getInterceptors() == null) {
return;
}
for (int i = getInterceptors().length - 1; i >= 0; i--) {
HandlerInterceptor interceptor = getInterceptors()[i];
interceptor.postHandle(request, response, this.handler, mv);
}
}