一、此接口测试用例
@RequestMapping(value = "/save_user",produces = "application/xml;charset=utf-8")
@ResponseBody
public Map<String,Object> saveUser(@RequestBody UserParam userParam) throws Exception{
log.info(" get user userParam:" + JSONUtil.toJsonStr(userParam));
Map<String,Object> user = new HashMap<String,Object>();
user.put("id",userParam.getAge() );
user.put("name",userParam.getName() );
return user;
// return "liming";
}dispatchServlet.xml配置
<mvc:annotation-driven>
<mvc:message-converters>
<bean class="com.tpw.component.AkResponseConverter"></bean>
<bean class="org.springframework.http.converter.StringHttpMessageConverter"/>
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"/>
<bean class="org.springframework.http.converter.xml.MappingJackson2XmlHttpMessageConverter"></bean>
</mvc:message-converters>
<mvc:argument-resolvers>
<bean class="com.tpw.component.RequestPropertiesArgumentResolver"></bean>
</mvc:argument-resolvers>
</mvc:annotation-driven>一、初始化加载解析器和转换器
请求参数由HandlerMethodArgumentResolver解析，返回参数由HandlerMethodReturnValueHandler来解析。这些解析器和返回值转换器存储在RequestMappingHandlerAdapter类中。
?1.系统初始化request的参数解析器，这个存储在
RequestMappingHandlerAdapter类的
private HandlerMethodArgumentResolverComposite argumentResolvers;? ? 2 初始化在RequestMappingHandlerAdapter.afterPropertiesSet方法中
public void afterPropertiesSet() {
// Do this first, it may add ResponseBody advice beans
initControllerAdviceCache();
if (this.argumentResolvers == null) {
List<HandlerMethodArgumentResolver> resolvers = getDefaultArgumentResolvers();
this.argumentResolvers = new HandlerMethodArgumentResolverComposite().addResolvers(resolvers);
}
if (this.initBinderArgumentResolvers == null) {
List<HandlerMethodArgumentResolver> resolvers = getDefaultInitBinderArgumentResolvers();
this.initBinderArgumentResolvers = new HandlerMethodArgumentResolverComposite().addResolvers(resolvers);
}
if (this.returnValueHandlers == null) {
List<HandlerMethodReturnValueHandler> handlers = getDefaultReturnValueHandlers();
this.returnValueHandlers = new HandlerMethodReturnValueHandlerComposite().addHandlers(handlers);
}
}?
3 然后会加载26个系统默认的参数解析器
private List<HandlerMethodArgumentResolver> getDefaultArgumentResolvers() {
List<HandlerMethodArgumentResolver> resolvers = new ArrayList<>(30);
// Annotation-based argument resolution
resolvers.add(new RequestParamMethodArgumentResolver(getBeanFactory(), false));
resolvers.add(new RequestParamMapMethodArgumentResolver());
resolvers.add(new PathVariableMethodArgumentResolver());
resolvers.add(new PathVariableMapMethodArgumentResolver());
resolvers.add(new MatrixVariableMethodArgumentResolver());
resolvers.add(new MatrixVariableMapMethodArgumentResolver());
resolvers.add(new ServletModelAttributeMethodProcessor(false));
resolvers.add(new RequestResponseBodyMethodProcessor(getMessageConverters(), this.requestResponseBodyAdvice));
resolvers.add(new RequestPartMethodArgumentResolver(getMessageConverters(), this.requestResponseBodyAdvice));
resolvers.add(new RequestHeaderMethodArgumentResolver(getBeanFactory()));
resolvers.add(new RequestHeaderMapMethodArgumentResolver());
resolvers.add(new ServletCookieValueMethodArgumentResolver(getBeanFactory()));
resolvers.add(new ExpressionValueMethodArgumentResolver(getBeanFactory()));
resolvers.add(new SessionAttributeMethodArgumentResolver());
resolvers.add(new RequestAttributeMethodArgumentResolver());
// Type-based argument resolution
resolvers.add(new ServletRequestMethodArgumentResolver());
resolvers.add(new ServletResponseMethodArgumentResolver());
resolvers.add(new HttpEntityMethodProcessor(getMessageConverters(), this.requestResponseBodyAdvice));
resolvers.add(new RedirectAttributesMethodArgumentResolver());
resolvers.add(new ModelMethodProcessor());
resolvers.add(new MapMethodProcessor());
resolvers.add(new ErrorsMethodArgumentResolver());
resolvers.add(new SessionStatusMethodArgumentResolver());
resolvers.add(new UriComponentsBuilderMethodArgumentResolver());
// Custom arguments
if (getCustomArgumentResolvers() != null) {
resolvers.addAll(getCustomArgumentResolvers());
}
// Catch-all
resolvers.add(new RequestParamMethodArgumentResolver(getBeanFactory(), true));
resolvers.add(new ServletModelAttributeMethodProcessor(true));
return resolvers;
}4 这里还会加载自定义参数解析器.自定义参数解析器在dispatch-servlet.xml配置
<mvc:annotation-driven>
<mvc:message-converters>
<bean class="org.springframework.http.converter.StringHttpMessageConverter"/>
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"/>
</mvc:message-converters>
<mvc:argument-resolvers>
<bean class="com.tpw.component.RequestPropertiesArgumentResolver"></bean>
</mvc:argument-resolvers>
</mvc:annotation-driven>即可。
5.默认的返回值转换器为
6.@RequestBody和@ResponseBody都由RequestResponseBodyMethodProcessor这个类负责转换。
@Override
public boolean supportsParameter(MethodParameter parameter) {
return parameter.hasParameterAnnotation(RequestBody.class);
}
@Override
public boolean supportsReturnType(MethodParameter returnType) {
return (AnnotatedElementUtils.hasAnnotation(returnType.getContainingClass(), ResponseBody.class) ||
returnType.hasMethodAnnotation(ResponseBody.class));
}7 如果是springboot项目，则写一个CONFIGUATION类实现WebMvcConfigurer接口即可。
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration的内部类会自动创建RequestMappingHandlerAdapter@Configuration(proxyBeanMethods = false)
public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration implements ResourceLoaderAware {@Configuration(proxyBeanMethods = false)
public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration implements ResourceLoaderAware {
@Bean
@Override
public RequestMappingHandlerAdapter requestMappingHandlerAdapter(
@Qualifier("mvcContentNegotiationManager") ContentNegotiationManager contentNegotiationManager,
@Qualifier("mvcConversionService") FormattingConversionService conversionService,
@Qualifier("mvcValidator") Validator validator) {
RequestMappingHandlerAdapter adapter = super.requestMappingHandlerAdapter(contentNegotiationManager,
conversionService, validator);
adapter.setIgnoreDefaultModelOnRedirect(
this.mvcProperties == null || this.mvcProperties.isIgnoreDefaultModelOnRedirect());
return adapter;
}然后会调用WebMvcConfigurationSupport.requestMappingHandlerAdapter
public RequestMappingHandlerAdapter requestMappingHandlerAdapter(
@Qualifier("mvcContentNegotiationManager") ContentNegotiationManager contentNegotiationManager,
@Qualifier("mvcConversionService") FormattingConversionService conversionService,
@Qualifier("mvcValidator") Validator validator) {
RequestMappingHandlerAdapter adapter = createRequestMappingHandlerAdapter();
adapter.setContentNegotiationManager(contentNegotiationManager);
adapter.setMessageConverters(getMessageConverters());
adapter.setWebBindingInitializer(getConfigurableWebBindingInitializer(conversionService, validator));
adapter.setCustomArgumentResolvers(getArgumentResolvers());
adapter.setCustomReturnValueHandlers(getReturnValueHandlers());
if (jackson2Present) {
adapter.setRequestBodyAdvice(Collections.singletonList(new JsonViewRequestBodyAdvice()));
adapter.setResponseBodyAdvice(Collections.singletonList(new JsonViewResponseBodyAdvice()));
}
AsyncSupportConfigurer configurer = new AsyncSupportConfigurer();
configureAsyncSupport(configurer);
if (configurer.getTaskExecutor() != null) {
adapter.setTaskExecutor(configurer.getTaskExecutor());
}
if (configurer.getTimeout() != null) {
adapter.setAsyncRequestTimeout(configurer.getTimeout());
}
adapter.setCallableInterceptors(configurer.getCallableInterceptors());
adapter.setDeferredResultInterceptors(configurer.getDeferredResultInterceptors());
return adapter;
}最终会调用WebMvcConfigurerComposite.addArgumentResolvers，这个类的List<WebMvcConfigurer> delegates 即为当前容器所有实现了WebMvcConfigurer接口的类。
WebMvcConfigurerComposite
@Override
public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
for (WebMvcConfigurer delegate : this.delegates) {
delegate.addArgumentResolvers(argumentResolvers);
}
}二、@RequestBody请求解析流程
??
??1.DispatcherServlet.doDispatch 中间会调用当前请求接口方法中所有支持的参数解析器，进行相应的参数解析和转换。
InvocableHandlerMethod.getMethodArgumentValuesprotected Object[] getMethodArgumentValues(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
MethodParameter[] parameters = getMethodParameters();
if (ObjectUtils.isEmpty(parameters)) {
return EMPTY_ARGS;
}
Object[] args = new Object[parameters.length];
for (int i = 0; i < parameters.length; i++) {
MethodParameter parameter = parameters[i];
parameter.initParameterNameDiscovery(this.parameterNameDiscoverer);
args[i] = findProvidedArgument(parameter, providedArgs);
if (args[i] != null) {
continue;
}
if (!this.resolvers.supportsParameter(parameter)) {
throw new IllegalStateException(formatArgumentError(parameter, "No suitable resolver"));
}
try {
args[i] = this.resolvers.resolveArgument(parameter, mavContainer, request, this.dataBinderFactory);
}
}
return args;
}
?这里面的this.resolvers的参数赋值来源于RequestMappingHandlerAdapter.invokeHandlerMethod，这个方法创建InvocableHandlerMethod，并设置解析器参数
@Nullable
protected ModelAndView invokeHandlerMethod(HttpServletRequest request,
HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
ServletWebRequest webRequest = new ServletWebRequest(request, response);
try {
WebDataBinderFactory binderFactory = getDataBinderFactory(handlerMethod);
ModelFactory modelFactory = getModelFactory(handlerMethod, binderFactory);
ServletInvocableHandlerMethod invocableMethod = createInvocableHandlerMethod(handlerMethod);
if (this.argumentResolvers != null) {
invocableMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
}
if (this.returnValueHandlers != null) {
invocableMethod.setHandlerMethodReturnValueHandlers(this.returnValueHandlers);
}
invocableMethod.setDataBinderFactory(binderFactory);
invocableMethod.setParameterNameDiscoverer(this.parameterNameDiscoverer);
ModelAndViewContainer mavContainer = new ModelAndViewContainer();
mavContainer.addAllAttributes(RequestContextUtils.getInputFlashMap(request));
modelFactory.initModel(webRequest, mavContainer, invocableMethod);
mavContainer.setIgnoreDefaultModelOnRedirect(this.ignoreDefaultModelOnRedirect);
AsyncWebRequest asyncWebRequest = WebAsyncUtils.createAsyncWebRequest(request, response);
asyncWebRequest.setTimeout(this.asyncRequestTimeout);
WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
asyncManager.setTaskExecutor(this.taskExecutor);
asyncManager.setAsyncWebRequest(asyncWebRequest);
asyncManager.registerCallableInterceptors(this.callableInterceptors);
asyncManager.registerDeferredResultInterceptors(this.deferredResultInterceptors);
invocableMethod.invokeAndHandle(webRequest, mavContainer);
if (asyncManager.isConcurrentHandlingStarted()) {
return null;
}
return getModelAndView(mavContainer, modelFactory, webRequest);
}
finally {
webRequest.requestCompleted();
}
}2.然后会调用RequestResponseBodyMethodProcessor.resolveArgument接口进行参数解析。
public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
parameter = parameter.nestedIfOptional();
Object arg = readWithMessageConverters(webRequest, parameter, parameter.getNestedGenericParameterType());
String name = Conventions.getVariableNameForParameter(parameter);
if (binderFactory != null) {
WebDataBinder binder = binderFactory.createBinder(webRequest, arg, name);
if (arg != null) {
validateIfApplicable(binder, parameter);
if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) {
throw new MethodArgumentNotValidException(parameter, binder.getBindingResult());
}
}
if (mavContainer != null) {
mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult());
}
}
return adaptArgumentIfNecessary(arg, parameter);
}?3.readWithMessageConverters(webRequest, parameter, parameter.getNestedGenericParameterType()) 最终会调用
AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters进行参数解析。此函数内会使用当前容器中所有的messageConvert类BEAN测试是否支持可读，如果可读的话，则进行messageConvert的读转换接口。
protected <T> Object readWithMessageConverters(HttpInputMessage inputMessage, MethodParameter parameter,
Type targetType) throws IOException, HttpMediaTypeNotSupportedException, HttpMessageNotReadableException {
MediaType contentType;
boolean noContentType = false;
Object body = NO_VALUE;
EmptyBodyCheckingHttpInputMessage message;
try {
message = new EmptyBodyCheckingHttpInputMessage(inputMessage);
for (HttpMessageConverter<?> converter : this.messageConverters) {
Class<HttpMessageConverter<?>> converterType = (Class<HttpMessageConverter<?>>) converter.getClass();
GenericHttpMessageConverter<?> genericConverter =
(converter instanceof GenericHttpMessageConverter ? (GenericHttpMessageConverter<?>) converter : null);
if (genericConverter != null ? genericConverter.canRead(targetType, contextClass, contentType) :
(targetClass != null && converter.canRead(targetClass, contentType))) {
if (message.hasBody()) {
HttpInputMessage msgToUse =
getAdvice().beforeBodyRead(message, parameter, targetType, converterType);
body = (genericConverter != null ? genericConverter.read(targetType, contextClass, msgToUse) :
((HttpMessageConverter<T>) converter).read(targetClass, msgToUse));
body = getAdvice().afterBodyRead(body, msgToUse, parameter, targetType, converterType);
}
else {
body = getAdvice().handleEmptyBody(null, message, parameter, targetType, converterType);
}
break;
}
}
}
return body;
}这里的messageConvert实际上是MappingJackson2HttpMessageConverter，他支持JSON转换
public MappingJackson2HttpMessageConverter(ObjectMapper objectMapper) {
super(objectMapper, MediaType.APPLICATION_JSON, new MediaType("application", "*+json"));
}
?4.resolveArgument方法中的validateIfApplicable(binder, parameter)会对带有@validate注解的参数进行校验。
5.解析完生成参数实体对象。
三、@Responsebody解析流程
1.接口方法执行完后，会调用HandlerMethodReturnValueHandlerComposite.
handleReturnValue进行转换。这里寻找系统中所有returnHandler,查找是否支持可写的HANDLER，进行处理。 public void handleReturnValue(@Nullable Object returnValue, MethodParameter returnType,
ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception {
HandlerMethodReturnValueHandler handler = selectHandler(returnValue, returnType);
if (handler == null) {
throw new IllegalArgumentException("Unknown return value type: " + returnType.getParameterType().getName());
}
handler.handleReturnValue(returnValue, returnType, mavContainer, webRequest);
}
找HANDLER的原则是看是否支持。
RequestResponseBodyMethodProcessor
public boolean supportsReturnType(MethodParameter returnType) {
return (AnnotatedElementUtils.hasAnnotation(returnType.getContainingClass(), ResponseBody.class) ||
returnType.hasMethodAnnotation(ResponseBody.class));
}?2.最终会调用到AbstractMessageConverterMethodProcessor.writeWithMessageConverters进行结果转换，这里又会寻找当前系统中所有的messageConvert类，找到支持写的类，进行数据转换。然后返回。
protected <T> void writeWithMessageConverters(@Nullable T value, MethodParameter returnType,
ServletServerHttpRequest inputMessage, ServletServerHttpResponse outputMessage)
throws IOException, HttpMediaTypeNotAcceptableException, HttpMessageNotWritableException {
Object body;
Class<?> valueType;
Type targetType;
if (selectedMediaType != null) {
selectedMediaType = selectedMediaType.removeQualityValue();
for (HttpMessageConverter<?> converter : this.messageConverters) {
GenericHttpMessageConverter genericConverter = (converter instanceof GenericHttpMessageConverter ?
(GenericHttpMessageConverter<?>) converter : null);
if (genericConverter != null ?
((GenericHttpMessageConverter) converter).canWrite(targetType, valueType, selectedMediaType) :
converter.canWrite(valueType, selectedMediaType)) {
body = getAdvice().beforeBodyWrite(body, returnType, selectedMediaType,
(Class<? extends HttpMessageConverter<?>>) converter.getClass(),
inputMessage, outputMessage);
if (body != null) {
Object theBody = body;
LogFormatUtils.traceDebug(logger, traceOn ->
"Writing [" + LogFormatUtils.formatValue(theBody, !traceOn) + "]");
addContentDispositionHeader(inputMessage, outputMessage);
if (genericConverter != null) {
genericConverter.write(body, targetType, selectedMediaType, outputMessage);
}
else {
((HttpMessageConverter) converter).write(body, selectedMediaType, outputMessage);
}
}
else {
if (logger.isDebugEnabled()) {
logger.debug("Nothing to write: null body");
}
}
return;
}
}
}
}
这里找到的是MappingJackson2XmlHttpMessageConverter
?最终通过objMapper进行对象转换。我这里配置的返回类型为XML.
?最终将XML的数据流写入resonse.